This adds support for emitting special sections such as initcall arrays,
PCI fixups and tracepoints as relative references rather than absolute
references. This reduces the size by 50% on 64-bit architectures, but
more importantly, it removes the need for carrying relocation metadata
for these sections in relocatables kernels (e.g., for KASLR) that need
to fix up these absolute references at boot time. On arm64, this reduces
the vmlinux footprint of such a reference by 8x (8 byte absolute reference
+ 24 byte RELA entry vs 4 byte relative reference)
Patch #3 was sent out before as a single patch. This series supersedes
the previous submission. This version makes relative ksymtab entries
dependent on the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS rather
than trying to infer from kbuild test robot replies for which architectures
it should be blacklisted.
Patch #1 introduces the new Kconfig symbol HAVE_ARCH_PREL32_RELOCATIONS,
and sets it for the main architectures that are expected to benefit the
most from this feature, i.e., 64-bit architectures or ones that use
runtime relocations.
Patches #4 - #6 implement relative references for initcalls, PCI fixups
and tracepoints, respectively, all of which produce sections with order
~1000 entries on an arm64 defconfig kernel with tracing enabled. This
means we save about 28 KB of vmlinux space for each of these patches.
Patches #7 - #10 have been added in v5, and implement relative references
in jump tables for arm64 and x86. On arm64, this results in significant
space savings (650+ KB on a typical distro kernel). On x86, the savings
are not as impressive, but still worthwhile. (Note that these patches
do not rely on CONFIG_HAVE_ARCH_PREL32_RELOCATIONS, given that the
inline asm that is emitted is already per-arch)
For the arm64 kernel, all patches combined reduce the memory footprint of
vmlinux by about 1.3 MB (using a config copied from Ubuntu that has KASLR
enabled), of which ~1 MB is the size reduction of the RELA section in .init,
and the remaining 300 KB is reduction of .text/.data.
Branch:
git://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git relative-special-sections-v7
Changes since v6:
- drop S390 from patch #1 introducing HAVE_ARCH_PREL32_RELOCATIONS: kbuild
robot threw me some s390 curveballs, and given that s390 does not define
CONFIG_RELOCATABLE in the first place, it does not benefit as much from
relative references as arm64, x86 and power do
- add patch to allow symbol exports to be disabled at compilation unit
granularity (#2)
- get rid of arm64 vmlinux.lds.S hunk to ensure code generated by __ADDRESSABLE
gets discarded from the EFI stub - it is no longer needed after adding #2 (#1)
- change _ADDRESSABLE() to emit a data reference, not a code reference - this
is another simplification made possible by patch #2 (#3)
- add Steven's ack to #6
- split x86 jump_label patch into two (#9, #10)
Changes since v5:
- add missing jump_label prototypes to s390 jump_label.h (#6)
- fix inverted condition in call to jump_entry_is_module_init() (#6)
Changes since v4:
- add patches to convert x86 and arm64 to use relative references for jump
tables (#6 - #8)
- rename PCI patch and add Bjorn's ack (#4)
- rebase onto v4.15-rc5
Changes since v3:
- fix module unload issue in patch #5 reported by Jessica, by reusing the
updated routine for_each_tracepoint_range() for the quiescent check at
module unload time; this requires this routine to be moved before
tracepoint_module_going() in kernel/tracepoint.c
- add Jessica's ack to #2
- rebase onto v4.14-rc1
Changes since v2:
- Revert my slightly misguided attempt to appease checkpatch, which resulted
in needless churn and worse code. This v3 is based on v1 with a few tweaks
that were actually reasonable checkpatch warnings: unnecessary braces (as
pointed out by Ingo) and other minor whitespace misdemeanors.
Changes since v1:
- Remove checkpatch errors to the extent feasible: in some cases, this
involves moving extern declarations into C files, and switching to
struct definitions rather than typedefs. Some errors are impossible
to fix: please find the remaining ones after the diffstat.
- Used 'int' instead if 'signed int' for the various offset fields: there
is no ambiguity between architectures regarding its signedness (unlike
'char')
- Refactor the different patches to be more uniform in the way they define
the section entry type and accessors in the .h file, and avoid the need to
add #ifdefs to the C code.
Cc: "H. Peter Anvin" <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Heiko Carstens <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Thomas Garnier <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Cc: Bjorn Helgaas <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Russell King <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: "David S. Miller" <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: James Morris <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Josh Poimboeuf <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Martin Schwidefsky <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Jessica Yu <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Ard Biesheuvel (10):
arch: enable relative relocations for arm64, power and x86
module: allow symbol exports to be disabled
module: use relative references for __ksymtab entries
init: allow initcall tables to be emitted using relative references
PCI: Add support for relative addressing in quirk tables
kernel: tracepoints: add support for relative references
kernel/jump_label: abstract jump_entry member accessors
arm64/kernel: jump_label: use relative references
x86: jump_label: switch to jump_entry accessors
x86/kernel: jump_table: use relative references
arch/Kconfig | 10 ++++
arch/arm/include/asm/jump_label.h | 27 +++++++++
arch/arm64/Kconfig | 1 +
arch/arm64/include/asm/jump_label.h | 48 +++++++++++++---
arch/arm64/kernel/jump_label.c | 22 +++++++-
arch/mips/include/asm/jump_label.h | 27 +++++++++
arch/powerpc/Kconfig | 1 +
arch/powerpc/include/asm/jump_label.h | 27 +++++++++
arch/s390/include/asm/jump_label.h | 27 +++++++++
arch/sparc/include/asm/jump_label.h | 27 +++++++++
arch/tile/include/asm/jump_label.h | 27 +++++++++
arch/x86/Kconfig | 1 +
arch/x86/boot/compressed/kaslr.c | 5 +-
arch/x86/include/asm/Kbuild | 1 +
arch/x86/include/asm/export.h | 5 --
arch/x86/include/asm/jump_label.h | 56 +++++++++++++++----
arch/x86/kernel/jump_label.c | 59 ++++++++++++++------
drivers/firmware/efi/libstub/Makefile | 3 +-
drivers/pci/quirks.c | 13 ++++-
include/asm-generic/export.h | 12 +++-
include/linux/compiler.h | 10 ++++
include/linux/export.h | 55 ++++++++++++++----
include/linux/init.h | 44 +++++++++++----
include/linux/pci.h | 20 +++++++
include/linux/tracepoint.h | 19 +++++--
init/main.c | 32 +++++------
kernel/jump_label.c | 38 ++++++-------
kernel/module.c | 33 +++++++++--
kernel/printk/printk.c | 4 +-
kernel/tracepoint.c | 50 +++++++++--------
security/security.c | 4 +-
tools/objtool/special.c | 4 +-
32 files changed, 560 insertions(+), 152 deletions(-)
delete mode 100644 arch/x86/include/asm/export.h
--
2.11.0
Before updating certain subsystems to use place relative 32-bit
relocations in special sections, to save space and reduce the
number of absolute relocations that need to be processed at runtime
by relocatable kernels, introduce the Kconfig symbol and define it
for some architectures that should be able to support and benefit
from it.
Cc: Catalin Marinas <[email protected]>
Cc: Will Deacon <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Michael Ellerman <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Cc: [email protected]
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/Kconfig | 10 ++++++++++
arch/arm64/Kconfig | 1 +
arch/powerpc/Kconfig | 1 +
arch/x86/Kconfig | 1 +
4 files changed, 13 insertions(+)
diff --git a/arch/Kconfig b/arch/Kconfig
index 400b9e1b2f27..dbc036a7bd1b 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -959,4 +959,14 @@ config REFCOUNT_FULL
against various use-after-free conditions that can be used in
security flaw exploits.
+config HAVE_ARCH_PREL32_RELOCATIONS
+ bool
+ help
+ May be selected by an architecture if it supports place-relative
+ 32-bit relocations, both in the toolchain and in the module loader,
+ in which case relative references can be used in special sections
+ for PCI fixup, initcalls etc which are only half the size on 64 bit
+ architectures, and don't require runtime relocation on relocatable
+ kernels.
+
source "kernel/gcov/Kconfig"
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index c9a7e9e1414f..66c7b9ab2a3d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -89,6 +89,7 @@ config ARM64
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index c51e6ce42e7a..e172478e2ae7 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -177,6 +177,7 @@ config PPC
select HAVE_ARCH_KGDB
select HAVE_ARCH_MMAP_RND_BITS
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select ARCH_HAS_STRICT_KERNEL_RWX if ((PPC_BOOK3S_64 || PPC32) && !RELOCATABLE && !HIBERNATION)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index d4fc98c50378..9f2bb853aedb 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -115,6 +115,7 @@ config X86
select HAVE_ARCH_MMAP_RND_BITS if MMU
select HAVE_ARCH_MMAP_RND_COMPAT_BITS if MMU && COMPAT
select HAVE_ARCH_COMPAT_MMAP_BASES if MMU && COMPAT
+ select HAVE_ARCH_PREL32_RELOCATIONS
select HAVE_ARCH_SECCOMP_FILTER
select HAVE_ARCH_TRACEHOOK
select HAVE_ARCH_TRANSPARENT_HUGEPAGE
--
2.11.0
To allow existing C code to be incorporated into the decompressor or
the UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx
declarations into nops, and #define it in places where such exports
are undesirable. Note that this gets rid of a rather dodgy redefine
of linux/export.h's header guard.
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/x86/boot/compressed/kaslr.c | 5 +----
drivers/firmware/efi/libstub/Makefile | 3 ++-
include/linux/export.h | 9 +++++++++
3 files changed, 12 insertions(+), 5 deletions(-)
diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
index 8199a6187251..3a2a6d7049e4 100644
--- a/arch/x86/boot/compressed/kaslr.c
+++ b/arch/x86/boot/compressed/kaslr.c
@@ -23,11 +23,8 @@
* _ctype[] in lib/ctype.c is needed by isspace() of linux/ctype.h.
* While both lib/ctype.c and lib/cmdline.c will bring EXPORT_SYMBOL
* which is meaningless and will cause compiling error in some cases.
- * So do not include linux/export.h and define EXPORT_SYMBOL(sym)
- * as empty.
*/
-#define _LINUX_EXPORT_H
-#define EXPORT_SYMBOL(sym)
+#define __DISABLE_EXPORTS
#include "misc.h"
#include "error.h"
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index adaa4a964f0c..312bd0b64a61 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -20,7 +20,8 @@ cflags-$(CONFIG_EFI_ARMSTUB) += -I$(srctree)/scripts/dtc/libfdt
KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
-D__NO_FORTIFY \
$(call cc-option,-ffreestanding) \
- $(call cc-option,-fno-stack-protector)
+ $(call cc-option,-fno-stack-protector) \
+ -D__DISABLE_EXPORTS
GCOV_PROFILE := n
KASAN_SANITIZE := n
diff --git a/include/linux/export.h b/include/linux/export.h
index 1a1dfdb2a5c6..6dba2fb08f77 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -83,6 +83,15 @@ extern struct module __this_module;
*/
#define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
+#elif defined(__DISABLE_EXPORTS)
+
+/*
+ * Allow symbol exports to be disabled completely so that C code may
+ * be reused in other execution contexts such as the UEFI stub or the
+ * decompressor.
+ */
+#define __EXPORT_SYMBOL(sym, sec)
+
#elif defined(CONFIG_TRIM_UNUSED_KSYMS)
#include <generated/autoksyms.h>
--
2.11.0
An ordinary arm64 defconfig build has ~64 KB worth of __ksymtab
entries, each consisting of two 64-bit fields containing absolute
references, to the symbol itself and to a char array containing
its name, respectively.
When we build the same configuration with KASLR enabled, we end
up with an additional ~192 KB of relocations in the .init section,
i.e., one 24 byte entry for each absolute reference, which all need
to be processed at boot time.
Given how the struct kernel_symbol that describes each entry is
completely local to module.c (except for the references emitted
by EXPORT_SYMBOL() itself), we can easily modify it to contain
two 32-bit relative references instead. This reduces the size of
the __ksymtab section by 50% for all 64-bit architectures, and
gets rid of the runtime relocations entirely for architectures
implementing KASLR, either via standard PIE linking (arm64) or
using custom host tools (x86).
Note that the binary search involving __ksymtab contents relies
on each section being sorted by symbol name. This is implemented
based on the input section names, not the names in the ksymtab
entries, so this patch does not interfere with that.
Given that the use of place-relative relocations requires support
both in the toolchain and in the module loader, we cannot enable
this feature for all architectures. So make it dependent on whether
CONFIG_HAVE_ARCH_PREL32_RELOCATIONS is defined.
Cc: Arnd Bergmann <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Thomas Garnier <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Acked-by: Jessica Yu <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/x86/include/asm/Kbuild | 1 +
arch/x86/include/asm/export.h | 5 ---
include/asm-generic/export.h | 12 ++++-
include/linux/compiler.h | 10 +++++
include/linux/export.h | 46 +++++++++++++++-----
kernel/module.c | 33 +++++++++++---
6 files changed, 83 insertions(+), 24 deletions(-)
diff --git a/arch/x86/include/asm/Kbuild b/arch/x86/include/asm/Kbuild
index 5d6a53fd7521..3e8a88dcaa1d 100644
--- a/arch/x86/include/asm/Kbuild
+++ b/arch/x86/include/asm/Kbuild
@@ -9,5 +9,6 @@ generated-y += xen-hypercalls.h
generic-y += clkdev.h
generic-y += dma-contiguous.h
generic-y += early_ioremap.h
+generic-y += export.h
generic-y += mcs_spinlock.h
generic-y += mm-arch-hooks.h
diff --git a/arch/x86/include/asm/export.h b/arch/x86/include/asm/export.h
deleted file mode 100644
index 2a51d66689c5..000000000000
--- a/arch/x86/include/asm/export.h
+++ /dev/null
@@ -1,5 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-#ifdef CONFIG_64BIT
-#define KSYM_ALIGN 16
-#endif
-#include <asm-generic/export.h>
diff --git a/include/asm-generic/export.h b/include/asm-generic/export.h
index 719db1968d81..97ce606459ae 100644
--- a/include/asm-generic/export.h
+++ b/include/asm-generic/export.h
@@ -5,12 +5,10 @@
#define KSYM_FUNC(x) x
#endif
#ifdef CONFIG_64BIT
-#define __put .quad
#ifndef KSYM_ALIGN
#define KSYM_ALIGN 8
#endif
#else
-#define __put .long
#ifndef KSYM_ALIGN
#define KSYM_ALIGN 4
#endif
@@ -25,6 +23,16 @@
#define KSYM(name) name
#endif
+.macro __put, val, name
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ .long \val - ., \name - .
+#elif defined(CONFIG_64BIT)
+ .quad \val, \name
+#else
+ .long \val, \name
+#endif
+.endm
+
/*
* note on .section use: @progbits vs %progbits nastiness doesn't matter,
* since we immediately emit into those sections anyway.
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index 52e611ab9a6c..79db4aa87d75 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -327,4 +327,14 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
compiletime_assert(__native_word(t), \
"Need native word sized stores/loads for atomicity.")
+/*
+ * Force the compiler to emit 'sym' as a symbol, so that we can reference
+ * it from inline assembler. Necessary in case 'sym' could be inlined
+ * otherwise, or eliminated entirely due to lack of references that are
+ * visible to the compiler.
+ */
+#define __ADDRESSABLE(sym) \
+ static void * const __attribute__((section(".discard"), used)) \
+ __PASTE(__addressable_##sym, __LINE__) = (void *)&sym;
+
#endif /* __LINUX_COMPILER_H */
diff --git a/include/linux/export.h b/include/linux/export.h
index 6dba2fb08f77..4744cf4736b0 100644
--- a/include/linux/export.h
+++ b/include/linux/export.h
@@ -24,12 +24,6 @@
#define VMLINUX_SYMBOL_STR(x) __VMLINUX_SYMBOL_STR(x)
#ifndef __ASSEMBLY__
-struct kernel_symbol
-{
- unsigned long value;
- const char *name;
-};
-
#ifdef MODULE
extern struct module __this_module;
#define THIS_MODULE (&__this_module)
@@ -60,17 +54,47 @@ extern struct module __this_module;
#define __CRC_SYMBOL(sym, sec)
#endif
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#include <linux/compiler.h>
+/*
+ * Emit the ksymtab entry as a pair of relative references: this reduces
+ * the size by half on 64-bit architectures, and eliminates the need for
+ * absolute relocations that require runtime processing on relocatable
+ * kernels.
+ */
+#define __KSYMTAB_ENTRY(sym, sec) \
+ __ADDRESSABLE(sym) \
+ asm(" .section \"___ksymtab" sec "+" #sym "\", \"a\" \n" \
+ " .balign 8 \n" \
+ VMLINUX_SYMBOL_STR(__ksymtab_##sym) ": \n" \
+ " .long " VMLINUX_SYMBOL_STR(sym) "- . \n" \
+ " .long " VMLINUX_SYMBOL_STR(__kstrtab_##sym) "- .\n" \
+ " .previous \n")
+
+struct kernel_symbol {
+ int value_offset;
+ int name_offset;
+};
+#else
+#define __KSYMTAB_ENTRY(sym, sec) \
+ static const struct kernel_symbol __ksymtab_##sym \
+ __attribute__((section("___ksymtab" sec "+" #sym), used)) \
+ = { (unsigned long)&sym, __kstrtab_##sym }
+
+struct kernel_symbol {
+ unsigned long value;
+ const char *name;
+};
+#endif
+
/* For every exported symbol, place a struct in the __ksymtab section */
#define ___EXPORT_SYMBOL(sym, sec) \
extern typeof(sym) sym; \
__CRC_SYMBOL(sym, sec) \
static const char __kstrtab_##sym[] \
- __attribute__((section("__ksymtab_strings"), aligned(1))) \
+ __attribute__((section("__ksymtab_strings"), used, aligned(1))) \
= VMLINUX_SYMBOL_STR(sym); \
- static const struct kernel_symbol __ksymtab_##sym \
- __used \
- __attribute__((section("___ksymtab" sec "+" #sym), used)) \
- = { (unsigned long)&sym, __kstrtab_##sym }
+ __KSYMTAB_ENTRY(sym, sec)
#if defined(__KSYM_DEPS__)
diff --git a/kernel/module.c b/kernel/module.c
index dea01ac9cb74..d3a908ffc42c 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -549,12 +549,31 @@ static bool check_symbol(const struct symsearch *syms,
return true;
}
+static unsigned long kernel_symbol_value(const struct kernel_symbol *sym)
+{
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ return (unsigned long)&sym->value_offset + sym->value_offset;
+#else
+ return sym->value;
+#endif
+}
+
+static const char *kernel_symbol_name(const struct kernel_symbol *sym)
+{
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ return (const char *)((unsigned long)&sym->name_offset +
+ sym->name_offset);
+#else
+ return sym->name;
+#endif
+}
+
static int cmp_name(const void *va, const void *vb)
{
const char *a;
const struct kernel_symbol *b;
a = va; b = vb;
- return strcmp(a, b->name);
+ return strcmp(a, kernel_symbol_name(b));
}
static bool find_symbol_in_section(const struct symsearch *syms,
@@ -2198,7 +2217,7 @@ void *__symbol_get(const char *symbol)
sym = NULL;
preempt_enable();
- return sym ? (void *)sym->value : NULL;
+ return sym ? (void *)kernel_symbol_value(sym) : NULL;
}
EXPORT_SYMBOL_GPL(__symbol_get);
@@ -2228,10 +2247,12 @@ static int verify_export_symbols(struct module *mod)
for (i = 0; i < ARRAY_SIZE(arr); i++) {
for (s = arr[i].sym; s < arr[i].sym + arr[i].num; s++) {
- if (find_symbol(s->name, &owner, NULL, true, false)) {
+ if (find_symbol(kernel_symbol_name(s), &owner, NULL,
+ true, false)) {
pr_err("%s: exports duplicate symbol %s"
" (owned by %s)\n",
- mod->name, s->name, module_name(owner));
+ mod->name, kernel_symbol_name(s),
+ module_name(owner));
return -ENOEXEC;
}
}
@@ -2280,7 +2301,7 @@ static int simplify_symbols(struct module *mod, const struct load_info *info)
ksym = resolve_symbol_wait(mod, info, name);
/* Ok if resolved. */
if (ksym && !IS_ERR(ksym)) {
- sym[i].st_value = ksym->value;
+ sym[i].st_value = kernel_symbol_value(ksym);
break;
}
@@ -2540,7 +2561,7 @@ static int is_exported(const char *name, unsigned long value,
ks = lookup_symbol(name, __start___ksymtab, __stop___ksymtab);
else
ks = lookup_symbol(name, mod->syms, mod->syms + mod->num_syms);
- return ks != NULL && ks->value == value;
+ return ks != NULL && kernel_symbol_value(ks) == value;
}
/* As per nm */
--
2.11.0
Allow the initcall tables to be emitted using relative references that
are only half the size on 64-bit architectures and don't require fixups
at runtime on relocatable kernels.
Cc: Petr Mladek <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: James Morris <[email protected]>
Cc: "Serge E. Hallyn" <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
---
include/linux/init.h | 44 +++++++++++++++-----
init/main.c | 32 +++++++-------
kernel/printk/printk.c | 4 +-
security/security.c | 4 +-
4 files changed, 53 insertions(+), 31 deletions(-)
diff --git a/include/linux/init.h b/include/linux/init.h
index ea1b31101d9e..cef8e817e5a5 100644
--- a/include/linux/init.h
+++ b/include/linux/init.h
@@ -109,8 +109,24 @@
typedef int (*initcall_t)(void);
typedef void (*exitcall_t)(void);
-extern initcall_t __con_initcall_start[], __con_initcall_end[];
-extern initcall_t __security_initcall_start[], __security_initcall_end[];
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+typedef int initcall_entry_t;
+
+static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
+{
+ return (initcall_t)((unsigned long)entry + *entry);
+}
+#else
+typedef initcall_t initcall_entry_t;
+
+static inline initcall_t initcall_from_entry(initcall_entry_t *entry)
+{
+ return *entry;
+}
+#endif
+
+extern initcall_entry_t __con_initcall_start[], __con_initcall_end[];
+extern initcall_entry_t __security_initcall_start[], __security_initcall_end[];
/* Used for contructor calls. */
typedef void (*ctor_fn_t)(void);
@@ -160,9 +176,20 @@ extern bool initcall_debug;
* as KEEP() in the linker script.
*/
-#define __define_initcall(fn, id) \
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define ___define_initcall(fn, id, __sec) \
+ __ADDRESSABLE(fn) \
+ asm(".section \"" #__sec ".init\", \"a\" \n" \
+ "__initcall_" #fn #id ": \n" \
+ ".long " VMLINUX_SYMBOL_STR(fn) " - . \n" \
+ ".previous \n");
+#else
+#define ___define_initcall(fn, id, __sec) \
static initcall_t __initcall_##fn##id __used \
- __attribute__((__section__(".initcall" #id ".init"))) = fn;
+ __attribute__((__section__(#__sec ".init"))) = fn;
+#endif
+
+#define __define_initcall(fn, id) ___define_initcall(fn, id, .initcall##id)
/*
* Early initcalls run before initializing SMP.
@@ -201,13 +228,8 @@ extern bool initcall_debug;
#define __exitcall(fn) \
static exitcall_t __exitcall_##fn __exit_call = fn
-#define console_initcall(fn) \
- static initcall_t __initcall_##fn \
- __used __section(.con_initcall.init) = fn
-
-#define security_initcall(fn) \
- static initcall_t __initcall_##fn \
- __used __section(.security_initcall.init) = fn
+#define console_initcall(fn) ___define_initcall(fn,, .con_initcall)
+#define security_initcall(fn) ___define_initcall(fn,, .security_initcall)
struct obs_kernel_param {
const char *str;
diff --git a/init/main.c b/init/main.c
index a8100b954839..d81487cc126d 100644
--- a/init/main.c
+++ b/init/main.c
@@ -848,18 +848,18 @@ int __init_or_module do_one_initcall(initcall_t fn)
}
-extern initcall_t __initcall_start[];
-extern initcall_t __initcall0_start[];
-extern initcall_t __initcall1_start[];
-extern initcall_t __initcall2_start[];
-extern initcall_t __initcall3_start[];
-extern initcall_t __initcall4_start[];
-extern initcall_t __initcall5_start[];
-extern initcall_t __initcall6_start[];
-extern initcall_t __initcall7_start[];
-extern initcall_t __initcall_end[];
-
-static initcall_t *initcall_levels[] __initdata = {
+extern initcall_entry_t __initcall_start[];
+extern initcall_entry_t __initcall0_start[];
+extern initcall_entry_t __initcall1_start[];
+extern initcall_entry_t __initcall2_start[];
+extern initcall_entry_t __initcall3_start[];
+extern initcall_entry_t __initcall4_start[];
+extern initcall_entry_t __initcall5_start[];
+extern initcall_entry_t __initcall6_start[];
+extern initcall_entry_t __initcall7_start[];
+extern initcall_entry_t __initcall_end[];
+
+static initcall_entry_t *initcall_levels[] __initdata = {
__initcall0_start,
__initcall1_start,
__initcall2_start,
@@ -885,7 +885,7 @@ static char *initcall_level_names[] __initdata = {
static void __init do_initcall_level(int level)
{
- initcall_t *fn;
+ initcall_entry_t *fn;
strcpy(initcall_command_line, saved_command_line);
parse_args(initcall_level_names[level],
@@ -895,7 +895,7 @@ static void __init do_initcall_level(int level)
NULL, &repair_env_string);
for (fn = initcall_levels[level]; fn < initcall_levels[level+1]; fn++)
- do_one_initcall(*fn);
+ do_one_initcall(initcall_from_entry(fn));
}
static void __init do_initcalls(void)
@@ -926,10 +926,10 @@ static void __init do_basic_setup(void)
static void __init do_pre_smp_initcalls(void)
{
- initcall_t *fn;
+ initcall_entry_t *fn;
for (fn = __initcall_start; fn < __initcall0_start; fn++)
- do_one_initcall(*fn);
+ do_one_initcall(initcall_from_entry(fn));
}
/*
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index b9006617710f..0516005261c7 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2611,7 +2611,7 @@ EXPORT_SYMBOL(unregister_console);
*/
void __init console_init(void)
{
- initcall_t *call;
+ initcall_entry_t *call;
/* Setup the default TTY line discipline. */
n_tty_init();
@@ -2622,7 +2622,7 @@ void __init console_init(void)
*/
call = __con_initcall_start;
while (call < __con_initcall_end) {
- (*call)();
+ initcall_from_entry(call)();
call++;
}
}
diff --git a/security/security.c b/security/security.c
index 1cd8526cb0b7..f648eeff06de 100644
--- a/security/security.c
+++ b/security/security.c
@@ -45,10 +45,10 @@ static __initdata char chosen_lsm[SECURITY_NAME_MAX + 1] =
static void __init do_security_initcalls(void)
{
- initcall_t *call;
+ initcall_entry_t *call;
call = __security_initcall_start;
while (call < __security_initcall_end) {
- (*call) ();
+ initcall_from_entry(call)();
call++;
}
}
--
2.11.0
To avoid the need for relocating absolute references to tracepoint
structures at boot time when running relocatable kernels (which may
take a disproportionate amount of space), add the option to emit
these tables as relative references instead.
Cc: Ingo Molnar <[email protected]>
Acked-by: Steven Rostedt (VMware) <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
---
include/linux/tracepoint.h | 19 ++++++--
kernel/tracepoint.c | 50 +++++++++++---------
2 files changed, 42 insertions(+), 27 deletions(-)
diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index a26ffbe09e71..d02bf1a695e8 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -228,6 +228,19 @@ extern void syscall_unregfunc(void);
return static_key_false(&__tracepoint_##name.key); \
}
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define __TRACEPOINT_ENTRY(name) \
+ asm(" .section \"__tracepoints_ptrs\", \"a\" \n" \
+ " .balign 4 \n" \
+ " .long " VMLINUX_SYMBOL_STR(__tracepoint_##name) " - .\n" \
+ " .previous \n")
+#else
+#define __TRACEPOINT_ENTRY(name) \
+ static struct tracepoint * const __tracepoint_ptr_##name __used \
+ __attribute__((section("__tracepoints_ptrs"))) = \
+ &__tracepoint_##name
+#endif
+
/*
* We have no guarantee that gcc and the linker won't up-align the tracepoint
* structures, so we create an array of pointers that will be used for iteration
@@ -237,11 +250,9 @@ extern void syscall_unregfunc(void);
static const char __tpstrtab_##name[] \
__attribute__((section("__tracepoints_strings"))) = #name; \
struct tracepoint __tracepoint_##name \
- __attribute__((section("__tracepoints"))) = \
+ __attribute__((section("__tracepoints"), used)) = \
{ __tpstrtab_##name, STATIC_KEY_INIT_FALSE, reg, unreg, NULL };\
- static struct tracepoint * const __tracepoint_ptr_##name __used \
- __attribute__((section("__tracepoints_ptrs"))) = \
- &__tracepoint_##name;
+ __TRACEPOINT_ENTRY(name);
#define DEFINE_TRACE(name) \
DEFINE_TRACE_FN(name, NULL, NULL);
diff --git a/kernel/tracepoint.c b/kernel/tracepoint.c
index 685c50ae6300..05649fef106c 100644
--- a/kernel/tracepoint.c
+++ b/kernel/tracepoint.c
@@ -327,6 +327,28 @@ int tracepoint_probe_unregister(struct tracepoint *tp, void *probe, void *data)
}
EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
+static void for_each_tracepoint_range(struct tracepoint * const *begin,
+ struct tracepoint * const *end,
+ void (*fct)(struct tracepoint *tp, void *priv),
+ void *priv)
+{
+ if (!begin)
+ return;
+
+ if (IS_ENABLED(CONFIG_HAVE_ARCH_PREL32_RELOCATIONS)) {
+ const int *iter;
+
+ for (iter = (const int *)begin; iter < (const int *)end; iter++)
+ fct((struct tracepoint *)((unsigned long)iter + *iter),
+ priv);
+ } else {
+ struct tracepoint * const *iter;
+
+ for (iter = begin; iter < end; iter++)
+ fct(*iter, priv);
+ }
+}
+
#ifdef CONFIG_MODULES
bool trace_module_has_bad_taint(struct module *mod)
{
@@ -391,15 +413,9 @@ EXPORT_SYMBOL_GPL(unregister_tracepoint_module_notifier);
* Ensure the tracer unregistered the module's probes before the module
* teardown is performed. Prevents leaks of probe and data pointers.
*/
-static void tp_module_going_check_quiescent(struct tracepoint * const *begin,
- struct tracepoint * const *end)
+static void tp_module_going_check_quiescent(struct tracepoint *tp, void *priv)
{
- struct tracepoint * const *iter;
-
- if (!begin)
- return;
- for (iter = begin; iter < end; iter++)
- WARN_ON_ONCE((*iter)->funcs);
+ WARN_ON_ONCE(tp->funcs);
}
static int tracepoint_module_coming(struct module *mod)
@@ -450,8 +466,9 @@ static void tracepoint_module_going(struct module *mod)
* Called the going notifier before checking for
* quiescence.
*/
- tp_module_going_check_quiescent(mod->tracepoints_ptrs,
- mod->tracepoints_ptrs + mod->num_tracepoints);
+ for_each_tracepoint_range(mod->tracepoints_ptrs,
+ mod->tracepoints_ptrs + mod->num_tracepoints,
+ tp_module_going_check_quiescent, NULL);
break;
}
}
@@ -503,19 +520,6 @@ static __init int init_tracepoints(void)
__initcall(init_tracepoints);
#endif /* CONFIG_MODULES */
-static void for_each_tracepoint_range(struct tracepoint * const *begin,
- struct tracepoint * const *end,
- void (*fct)(struct tracepoint *tp, void *priv),
- void *priv)
-{
- struct tracepoint * const *iter;
-
- if (!begin)
- return;
- for (iter = begin; iter < end; iter++)
- fct(*iter, priv);
-}
-
/**
* for_each_kernel_tracepoint - iteration on all kernel tracepoints
* @fct: callback
--
2.11.0
In preparation of allowing architectures to use relative references
in jump_label entries [which can dramatically reduce the memory
footprint], introduce abstractions for references to the 'code' and
'key' members of struct jump_entry.
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/arm/include/asm/jump_label.h | 27 ++++++++++++++
arch/arm64/include/asm/jump_label.h | 27 ++++++++++++++
arch/mips/include/asm/jump_label.h | 27 ++++++++++++++
arch/powerpc/include/asm/jump_label.h | 27 ++++++++++++++
arch/s390/include/asm/jump_label.h | 27 ++++++++++++++
arch/sparc/include/asm/jump_label.h | 27 ++++++++++++++
arch/tile/include/asm/jump_label.h | 27 ++++++++++++++
arch/x86/include/asm/jump_label.h | 27 ++++++++++++++
kernel/jump_label.c | 38 +++++++++-----------
9 files changed, 232 insertions(+), 22 deletions(-)
diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
index e12d7d096fc0..7b05b404063a 100644
--- a/arch/arm/include/asm/jump_label.h
+++ b/arch/arm/include/asm/jump_label.h
@@ -45,5 +45,32 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index 1b5e0e843c3a..9d6e46355c89 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -62,5 +62,32 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* __ASSEMBLY__ */
#endif /* __ASM_JUMP_LABEL_H */
diff --git a/arch/mips/include/asm/jump_label.h b/arch/mips/include/asm/jump_label.h
index e77672539e8e..70df9293dc49 100644
--- a/arch/mips/include/asm/jump_label.h
+++ b/arch/mips/include/asm/jump_label.h
@@ -66,5 +66,32 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_MIPS_JUMP_LABEL_H */
diff --git a/arch/powerpc/include/asm/jump_label.h b/arch/powerpc/include/asm/jump_label.h
index 9a287e0ac8b1..412b2699c9f6 100644
--- a/arch/powerpc/include/asm/jump_label.h
+++ b/arch/powerpc/include/asm/jump_label.h
@@ -59,6 +59,33 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#else
#define ARCH_STATIC_BRANCH(LABEL, KEY) \
1098: nop; \
diff --git a/arch/s390/include/asm/jump_label.h b/arch/s390/include/asm/jump_label.h
index 40f651292aa7..1ecfd46835d9 100644
--- a/arch/s390/include/asm/jump_label.h
+++ b/arch/s390/include/asm/jump_label.h
@@ -50,5 +50,32 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/sparc/include/asm/jump_label.h b/arch/sparc/include/asm/jump_label.h
index 94eb529dcb77..18e893687f7c 100644
--- a/arch/sparc/include/asm/jump_label.h
+++ b/arch/sparc/include/asm/jump_label.h
@@ -48,5 +48,32 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* __ASSEMBLY__ */
#endif
diff --git a/arch/tile/include/asm/jump_label.h b/arch/tile/include/asm/jump_label.h
index cde7573f397b..86acaa6ff33d 100644
--- a/arch/tile/include/asm/jump_label.h
+++ b/arch/tile/include/asm/jump_label.h
@@ -55,4 +55,31 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#endif /* _ASM_TILE_JUMP_LABEL_H */
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 8c0de4282659..009ff2699d07 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -74,6 +74,33 @@ struct jump_entry {
jump_label_t key;
};
+static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
+{
+ return entry->code;
+}
+
+static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
+{
+ return (struct static_key *)((unsigned long)entry->key & ~1UL);
+}
+
+static inline bool jump_entry_is_branch(const struct jump_entry *entry)
+{
+ return (unsigned long)entry->key & 1UL;
+}
+
+static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
+{
+ return entry->code == 0;
+}
+
+static inline void jump_entry_set_module_init(struct jump_entry *entry)
+{
+ entry->code = 0;
+}
+
+#define jump_label_swap NULL
+
#else /* __ASSEMBLY__ */
.macro STATIC_JUMP_IF_TRUE target, key, def
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 8594d24e4adc..4f44db58d981 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -37,10 +37,12 @@ static int jump_label_cmp(const void *a, const void *b)
const struct jump_entry *jea = a;
const struct jump_entry *jeb = b;
- if (jea->key < jeb->key)
+ if ((unsigned long)jump_entry_key(jea) <
+ (unsigned long)jump_entry_key(jeb))
return -1;
- if (jea->key > jeb->key)
+ if ((unsigned long)jump_entry_key(jea) >
+ (unsigned long)jump_entry_key(jeb))
return 1;
return 0;
@@ -53,7 +55,8 @@ jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
size = (((unsigned long)stop - (unsigned long)start)
/ sizeof(struct jump_entry));
- sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
+ sort(start, size, sizeof(struct jump_entry), jump_label_cmp,
+ jump_label_swap);
}
static void jump_label_update(struct static_key *key);
@@ -254,8 +257,8 @@ EXPORT_SYMBOL_GPL(jump_label_rate_limit);
static int addr_conflict(struct jump_entry *entry, void *start, void *end)
{
- if (entry->code <= (unsigned long)end &&
- entry->code + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
+ if (jump_entry_code(entry) <= (unsigned long)end &&
+ jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE > (unsigned long)start)
return 1;
return 0;
@@ -314,16 +317,6 @@ static inline void static_key_set_linked(struct static_key *key)
key->type |= JUMP_TYPE_LINKED;
}
-static inline struct static_key *jump_entry_key(struct jump_entry *entry)
-{
- return (struct static_key *)((unsigned long)entry->key & ~1UL);
-}
-
-static bool jump_entry_branch(struct jump_entry *entry)
-{
- return (unsigned long)entry->key & 1UL;
-}
-
/***
* A 'struct static_key' uses a union such that it either points directly
* to a table of 'struct jump_entry' or to a linked list of modules which in
@@ -348,7 +341,7 @@ static enum jump_label_type jump_label_type(struct jump_entry *entry)
{
struct static_key *key = jump_entry_key(entry);
bool enabled = static_key_enabled(key);
- bool branch = jump_entry_branch(entry);
+ bool branch = jump_entry_is_branch(entry);
/* See the comment in linux/jump_label.h */
return enabled ^ branch;
@@ -364,7 +357,8 @@ static void __jump_label_update(struct static_key *key,
* kernel_text_address() verifies we are not in core kernel
* init code, see jump_label_invalidate_module_init().
*/
- if (entry->code && kernel_text_address(entry->code))
+ if (!jump_entry_is_module_init(entry) &&
+ kernel_text_address(jump_entry_code(entry)))
arch_jump_label_transform(entry, jump_label_type(entry));
}
}
@@ -417,7 +411,7 @@ static enum jump_label_type jump_label_init_type(struct jump_entry *entry)
{
struct static_key *key = jump_entry_key(entry);
bool type = static_key_type(key);
- bool branch = jump_entry_branch(entry);
+ bool branch = jump_entry_is_branch(entry);
/* See the comment in linux/jump_label.h */
return type ^ branch;
@@ -541,7 +535,7 @@ static int jump_label_add_module(struct module *mod)
continue;
key = iterk;
- if (within_module(iter->key, mod)) {
+ if (within_module((unsigned long)key, mod)) {
static_key_set_entries(key, iter);
continue;
}
@@ -591,7 +585,7 @@ static void jump_label_del_module(struct module *mod)
key = jump_entry_key(iter);
- if (within_module(iter->key, mod))
+ if (within_module((unsigned long)key, mod))
continue;
/* No memory during module load */
@@ -634,8 +628,8 @@ static void jump_label_invalidate_module_init(struct module *mod)
struct jump_entry *iter;
for (iter = iter_start; iter < iter_stop; iter++) {
- if (within_module_init(iter->code, mod))
- iter->code = 0;
+ if (within_module_init(jump_entry_code(iter), mod))
+ jump_entry_set_module_init(iter);
}
}
--
2.11.0
On a randomly chosen distro kernel build for arm64, vmlinux.o shows the
following sections, containing jump label entries, and the associated
RELA relocation records, respectively:
...
[38088] __jump_table PROGBITS 0000000000000000 00e19f30
000000000002ea10 0000000000000000 WA 0 0 8
[38089] .rela__jump_table RELA 0000000000000000 01fd8bb0
000000000008be30 0000000000000018 I 38178 38088 8
...
In other words, we have 190 KB worth of 'struct jump_entry' instances,
and 573 KB worth of RELA entries to relocate each entry's code, target
and key members. This means the RELA section occupies 10% of the .init
segment, and the two sections combined represent 5% of vmlinux's entire
memory footprint.
So let's switch from 64-bit absolute references to 32-bit relative
references: this reduces the size of the __jump_table by 50%, and gets
rid of the RELA section entirely.
Note that this requires some extra care in the sorting routine, given
that the offsets change when entries are moved around in the jump_entry
table.
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/arm64/include/asm/jump_label.h | 27 ++++++++++++--------
arch/arm64/kernel/jump_label.c | 22 +++++++++++++---
2 files changed, 36 insertions(+), 13 deletions(-)
diff --git a/arch/arm64/include/asm/jump_label.h b/arch/arm64/include/asm/jump_label.h
index 9d6e46355c89..8f82adeb7b0b 100644
--- a/arch/arm64/include/asm/jump_label.h
+++ b/arch/arm64/include/asm/jump_label.h
@@ -30,8 +30,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
{
asm goto("1: nop\n\t"
".pushsection __jump_table, \"aw\"\n\t"
- ".align 3\n\t"
- ".quad 1b, %l[l_yes], %c0\n\t"
+ ".align 2\n\t"
+ ".long 1b - ., %l[l_yes] - ., %c0 - .\n\t"
".popsection\n\t"
: : "i"(&((char *)key)[branch]) : : l_yes);
@@ -44,8 +44,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
{
asm goto("1: b %l[l_yes]\n\t"
".pushsection __jump_table, \"aw\"\n\t"
- ".align 3\n\t"
- ".quad 1b, %l[l_yes], %c0\n\t"
+ ".align 2\n\t"
+ ".long 1b - ., %l[l_yes] - ., %c0 - .\n\t"
".popsection\n\t"
: : "i"(&((char *)key)[branch]) : : l_yes);
@@ -57,19 +57,26 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
typedef u64 jump_label_t;
struct jump_entry {
- jump_label_t code;
- jump_label_t target;
- jump_label_t key;
+ s32 code;
+ s32 target;
+ s32 key;
};
static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
{
- return entry->code;
+ return (unsigned long)&entry->code + entry->code;
+}
+
+static inline jump_label_t jump_entry_target(const struct jump_entry *entry)
+{
+ return (unsigned long)&entry->target + entry->target;
}
static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
{
- return (struct static_key *)((unsigned long)entry->key & ~1UL);
+ unsigned long key = (unsigned long)&entry->key + entry->key;
+
+ return (struct static_key *)(key & ~1UL);
}
static inline bool jump_entry_is_branch(const struct jump_entry *entry)
@@ -87,7 +94,7 @@ static inline void jump_entry_set_module_init(struct jump_entry *entry)
entry->code = 0;
}
-#define jump_label_swap NULL
+void jump_label_swap(void *a, void *b, int size);
#endif /* __ASSEMBLY__ */
#endif /* __ASM_JUMP_LABEL_H */
diff --git a/arch/arm64/kernel/jump_label.c b/arch/arm64/kernel/jump_label.c
index c2dd1ad3e648..2b8e459e91f7 100644
--- a/arch/arm64/kernel/jump_label.c
+++ b/arch/arm64/kernel/jump_label.c
@@ -25,12 +25,12 @@
void arch_jump_label_transform(struct jump_entry *entry,
enum jump_label_type type)
{
- void *addr = (void *)entry->code;
+ void *addr = (void *)jump_entry_code(entry);
u32 insn;
if (type == JUMP_LABEL_JMP) {
- insn = aarch64_insn_gen_branch_imm(entry->code,
- entry->target,
+ insn = aarch64_insn_gen_branch_imm(jump_entry_code(entry),
+ jump_entry_target(entry),
AARCH64_INSN_BRANCH_NOLINK);
} else {
insn = aarch64_insn_gen_nop();
@@ -50,4 +50,20 @@ void arch_jump_label_transform_static(struct jump_entry *entry,
*/
}
+void jump_label_swap(void *a, void *b, int size)
+{
+ long delta = (unsigned long)a - (unsigned long)b;
+ struct jump_entry *jea = a;
+ struct jump_entry *jeb = b;
+ struct jump_entry tmp = *jea;
+
+ jea->code = jeb->code - delta;
+ jea->target = jeb->target - delta;
+ jea->key = jeb->key - delta;
+
+ jeb->code = tmp.code + delta;
+ jeb->target = tmp.target + delta;
+ jeb->key = tmp.key + delta;
+}
+
#endif /* HAVE_JUMP_LABEL */
--
2.11.0
In preparation of switching x86 to use place-relative references for
the code, target and key members of struct jump_entry, replace direct
references to the struct member with invocations of the new accessors.
This will allow us to make the switch by modifying the accessors only.
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/x86/kernel/jump_label.c | 43 ++++++++++++--------
1 file changed, 26 insertions(+), 17 deletions(-)
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index e56c95be2808..d64296092ef5 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -52,22 +52,24 @@ static void __jump_label_transform(struct jump_entry *entry,
* Jump label is enabled for the first time.
* So we expect a default_nop...
*/
- if (unlikely(memcmp((void *)entry->code, default_nop, 5)
- != 0))
- bug_at((void *)entry->code, __LINE__);
+ if (unlikely(memcmp((void *)jump_entry_code(entry),
+ default_nop, 5) != 0))
+ bug_at((void *)jump_entry_code(entry),
+ __LINE__);
} else {
/*
* ...otherwise expect an ideal_nop. Otherwise
* something went horribly wrong.
*/
- if (unlikely(memcmp((void *)entry->code, ideal_nop, 5)
- != 0))
- bug_at((void *)entry->code, __LINE__);
+ if (unlikely(memcmp((void *)jump_entry_code(entry),
+ ideal_nop, 5) != 0))
+ bug_at((void *)jump_entry_code(entry),
+ __LINE__);
}
code.jump = 0xe9;
- code.offset = entry->target -
- (entry->code + JUMP_LABEL_NOP_SIZE);
+ code.offset = jump_entry_target(entry) -
+ (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
} else {
/*
* We are disabling this jump label. If it is not what
@@ -76,14 +78,18 @@ static void __jump_label_transform(struct jump_entry *entry,
* are converting the default nop to the ideal nop.
*/
if (init) {
- if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))
- bug_at((void *)entry->code, __LINE__);
+ if (unlikely(memcmp((void *)jump_entry_code(entry),
+ default_nop, 5) != 0))
+ bug_at((void *)jump_entry_code(entry),
+ __LINE__);
} else {
code.jump = 0xe9;
- code.offset = entry->target -
- (entry->code + JUMP_LABEL_NOP_SIZE);
- if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))
- bug_at((void *)entry->code, __LINE__);
+ code.offset = jump_entry_target(entry) -
+ (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
+ if (unlikely(memcmp((void *)jump_entry_code(entry),
+ &code, 5) != 0))
+ bug_at((void *)jump_entry_code(entry),
+ __LINE__);
}
memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
}
@@ -97,10 +103,13 @@ static void __jump_label_transform(struct jump_entry *entry,
*
*/
if (poker)
- (*poker)((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE);
+ (*poker)((void *)jump_entry_code(entry), &code,
+ JUMP_LABEL_NOP_SIZE);
else
- text_poke_bp((void *)entry->code, &code, JUMP_LABEL_NOP_SIZE,
- (void *)entry->code + JUMP_LABEL_NOP_SIZE);
+ text_poke_bp((void *)jump_entry_code(entry), &code,
+ JUMP_LABEL_NOP_SIZE,
+ (void *)jump_entry_code(entry) +
+ JUMP_LABEL_NOP_SIZE);
}
void arch_jump_label_transform(struct jump_entry *entry,
--
2.11.0
Similar to the arm64 case, 64-bit x86 can benefit from using 32-bit
relative references rather than 64-bit absolute ones when emitting
struct jump_entry instances. Not only does this reduce the memory
footprint of the entries themselves by 50%, it also removes the need
for carrying relocation metadata on relocatable builds (i.e., for KASLR)
which saves a fair chunk of .init space as well (although the savings
are not as dramatic as on arm64)
Signed-off-by: Ard Biesheuvel <[email protected]>
---
arch/x86/include/asm/jump_label.h | 35 ++++++++++++--------
arch/x86/kernel/jump_label.c | 16 +++++++++
tools/objtool/special.c | 4 +--
3 files changed, 39 insertions(+), 16 deletions(-)
diff --git a/arch/x86/include/asm/jump_label.h b/arch/x86/include/asm/jump_label.h
index 009ff2699d07..35fc2c5ec846 100644
--- a/arch/x86/include/asm/jump_label.h
+++ b/arch/x86/include/asm/jump_label.h
@@ -36,8 +36,8 @@ static __always_inline bool arch_static_branch(struct static_key *key, bool bran
asm_volatile_goto("1:"
".byte " __stringify(STATIC_KEY_INIT_NOP) "\n\t"
".pushsection __jump_table, \"aw\" \n\t"
- _ASM_ALIGN "\n\t"
- _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+ ".balign 4\n\t"
+ ".long 1b - ., %l[l_yes] - ., %c0 + %c1 - .\n\t"
".popsection \n\t"
: : "i" (key), "i" (branch) : : l_yes);
@@ -52,8 +52,8 @@ static __always_inline bool arch_static_branch_jump(struct static_key *key, bool
".byte 0xe9\n\t .long %l[l_yes] - 2f\n\t"
"2:\n\t"
".pushsection __jump_table, \"aw\" \n\t"
- _ASM_ALIGN "\n\t"
- _ASM_PTR "1b, %l[l_yes], %c0 + %c1 \n\t"
+ ".balign 4\n\t"
+ ".long 1b - ., %l[l_yes] - ., %c0 + %c1 - .\n\t"
".popsection \n\t"
: : "i" (key), "i" (branch) : : l_yes);
@@ -69,19 +69,26 @@ typedef u32 jump_label_t;
#endif
struct jump_entry {
- jump_label_t code;
- jump_label_t target;
- jump_label_t key;
+ s32 code;
+ s32 target;
+ s32 key;
};
static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
{
- return entry->code;
+ return (unsigned long)&entry->code + entry->code;
+}
+
+static inline jump_label_t jump_entry_target(const struct jump_entry *entry)
+{
+ return (unsigned long)&entry->target + entry->target;
}
static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
{
- return (struct static_key *)((unsigned long)entry->key & ~1UL);
+ unsigned long key = (unsigned long)&entry->key + entry->key;
+
+ return (struct static_key *)(key & ~1UL);
}
static inline bool jump_entry_is_branch(const struct jump_entry *entry)
@@ -99,7 +106,7 @@ static inline void jump_entry_set_module_init(struct jump_entry *entry)
entry->code = 0;
}
-#define jump_label_swap NULL
+void jump_label_swap(void *a, void *b, int size);
#else /* __ASSEMBLY__ */
@@ -114,8 +121,8 @@ static inline void jump_entry_set_module_init(struct jump_entry *entry)
.byte STATIC_KEY_INIT_NOP
.endif
.pushsection __jump_table, "aw"
- _ASM_ALIGN
- _ASM_PTR .Lstatic_jump_\@, \target, \key
+ .balign 4
+ .long .Lstatic_jump_\@ - ., \target - ., \key - .
.popsection
.endm
@@ -130,8 +137,8 @@ static inline void jump_entry_set_module_init(struct jump_entry *entry)
.Lstatic_jump_after_\@:
.endif
.pushsection __jump_table, "aw"
- _ASM_ALIGN
- _ASM_PTR .Lstatic_jump_\@, \target, \key + 1
+ .balign 4
+ .long .Lstatic_jump_\@ - ., \target - ., \key + 1 - .
.popsection
.endm
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index d64296092ef5..cc5034b42335 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -149,4 +149,20 @@ __init_or_module void arch_jump_label_transform_static(struct jump_entry *entry,
__jump_label_transform(entry, type, text_poke_early, 1);
}
+void jump_label_swap(void *a, void *b, int size)
+{
+ long delta = (unsigned long)a - (unsigned long)b;
+ struct jump_entry *jea = a;
+ struct jump_entry *jeb = b;
+ struct jump_entry tmp = *jea;
+
+ jea->code = jeb->code - delta;
+ jea->target = jeb->target - delta;
+ jea->key = jeb->key - delta;
+
+ jeb->code = tmp.code + delta;
+ jeb->target = tmp.target + delta;
+ jeb->key = tmp.key + delta;
+}
+
#endif
diff --git a/tools/objtool/special.c b/tools/objtool/special.c
index 84f001d52322..98ae55b39037 100644
--- a/tools/objtool/special.c
+++ b/tools/objtool/special.c
@@ -30,9 +30,9 @@
#define EX_ORIG_OFFSET 0
#define EX_NEW_OFFSET 4
-#define JUMP_ENTRY_SIZE 24
+#define JUMP_ENTRY_SIZE 12
#define JUMP_ORIG_OFFSET 0
-#define JUMP_NEW_OFFSET 8
+#define JUMP_NEW_OFFSET 4
#define ALT_ENTRY_SIZE 13
#define ALT_ORIG_OFFSET 0
--
2.11.0
Allow the PCI quirk tables to be emitted in a way that avoids absolute
references to the hook functions. This reduces the size of the entries,
and, more importantly, makes them invariant under runtime relocation
(e.g., for KASLR)
Acked-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Ard Biesheuvel <[email protected]>
---
drivers/pci/quirks.c | 13 ++++++++++---
include/linux/pci.h | 20 ++++++++++++++++++++
2 files changed, 30 insertions(+), 3 deletions(-)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 10684b17d0bd..b6d51b4d5ce1 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -3556,9 +3556,16 @@ static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
f->vendor == (u16) PCI_ANY_ID) &&
(f->device == dev->device ||
f->device == (u16) PCI_ANY_ID)) {
- calltime = fixup_debug_start(dev, f->hook);
- f->hook(dev);
- fixup_debug_report(dev, calltime, f->hook);
+ void (*hook)(struct pci_dev *dev);
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ hook = (void *)((unsigned long)&f->hook_offset +
+ f->hook_offset);
+#else
+ hook = f->hook;
+#endif
+ calltime = fixup_debug_start(dev, hook);
+ hook(dev);
+ fixup_debug_report(dev, calltime, hook);
}
}
diff --git a/include/linux/pci.h b/include/linux/pci.h
index c170c9250c8b..086c3965710b 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -1792,7 +1792,11 @@ struct pci_fixup {
u16 device; /* You can use PCI_ANY_ID here of course */
u32 class; /* You can use PCI_ANY_ID here too */
unsigned int class_shift; /* should be 0, 8, 16 */
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+ int hook_offset;
+#else
void (*hook)(struct pci_dev *dev);
+#endif
};
enum pci_fixup_pass {
@@ -1806,12 +1810,28 @@ enum pci_fixup_pass {
pci_fixup_suspend_late, /* pci_device_suspend_late() */
};
+#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
+#define __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \
+ class_shift, hook) \
+ __ADDRESSABLE(hook) \
+ asm(".section " #sec ", \"a\" \n" \
+ ".balign 16 \n" \
+ ".short " #vendor ", " #device " \n" \
+ ".long " #class ", " #class_shift " \n" \
+ ".long " VMLINUX_SYMBOL_STR(hook) " - . \n" \
+ ".previous \n");
+#define DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \
+ class_shift, hook) \
+ __DECLARE_PCI_FIXUP_SECTION(sec, name, vendor, device, class, \
+ class_shift, hook)
+#else
/* Anonymous variables would be nice... */
#define DECLARE_PCI_FIXUP_SECTION(section, name, vendor, device, class, \
class_shift, hook) \
static const struct pci_fixup __PASTE(__pci_fixup_##name,__LINE__) __used \
__attribute__((__section__(#section), aligned((sizeof(void *))))) \
= { vendor, device, class, class_shift, hook };
+#endif
#define DECLARE_PCI_FIXUP_CLASS_EARLY(vendor, device, class, \
class_shift, hook) \
--
2.11.0
On Tue, 2 Jan 2018, Ard Biesheuvel wrote:
> To allow existing C code to be incorporated into the decompressor or
> the UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx
> declarations into nops, and #define it in places where such exports
> are undesirable. Note that this gets rid of a rather dodgy redefine
> of linux/export.h's header guard.
[...]
> --- a/include/linux/export.h
> +++ b/include/linux/export.h
> @@ -83,6 +83,15 @@ extern struct module __this_module;
> */
> #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
>
> +#elif defined(__DISABLE_EXPORTS)
> +
> +/*
> + * Allow symbol exports to be disabled completely so that C code may
> + * be reused in other execution contexts such as the UEFI stub or the
> + * decompressor.
> + */
> +#define __EXPORT_SYMBOL(sym, sec)
> +
I think you should rather put this first thing in the #if sequence so to
override the defined(__KSYM_DEPS__) case too. No need to create build
dependencies for module symbols that you're going to stub out
afterwards anyway.
Nicolas
On 2 January 2018 at 23:47, Nicolas Pitre <[email protected]> wrote:
> On Tue, 2 Jan 2018, Ard Biesheuvel wrote:
>
>> To allow existing C code to be incorporated into the decompressor or
>> the UEFI stub, introduce a CPP macro that turns all EXPORT_SYMBOL_xxx
>> declarations into nops, and #define it in places where such exports
>> are undesirable. Note that this gets rid of a rather dodgy redefine
>> of linux/export.h's header guard.
> [...]
>
>> --- a/include/linux/export.h
>> +++ b/include/linux/export.h
>> @@ -83,6 +83,15 @@ extern struct module __this_module;
>> */
>> #define __EXPORT_SYMBOL(sym, sec) === __KSYM_##sym ===
>>
>> +#elif defined(__DISABLE_EXPORTS)
>> +
>> +/*
>> + * Allow symbol exports to be disabled completely so that C code may
>> + * be reused in other execution contexts such as the UEFI stub or the
>> + * decompressor.
>> + */
>> +#define __EXPORT_SYMBOL(sym, sec)
>> +
>
> I think you should rather put this first thing in the #if sequence so to
> override the defined(__KSYM_DEPS__) case too. No need to create build
> dependencies for module symbols that you're going to stub out
> afterwards anyway.
>
I wasn't sure, so thanks for clearing that up.
On Tue, Jan 02, 2018 at 08:05:44PM +0000, Ard Biesheuvel wrote:
> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
> index 10684b17d0bd..b6d51b4d5ce1 100644
> --- a/drivers/pci/quirks.c
> +++ b/drivers/pci/quirks.c
> @@ -3556,9 +3556,16 @@ static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
> f->vendor == (u16) PCI_ANY_ID) &&
> (f->device == dev->device ||
> f->device == (u16) PCI_ANY_ID)) {
> - calltime = fixup_debug_start(dev, f->hook);
> - f->hook(dev);
> - fixup_debug_report(dev, calltime, f->hook);
> + void (*hook)(struct pci_dev *dev);
> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
> + hook = (void *)((unsigned long)&f->hook_offset +
> + f->hook_offset);
> +#else
> + hook = f->hook;
> +#endif
More of a nitpick but I've seen this pattern in several places in your
code, maybe worth defining a macro (couldn't come up with a better
name):
#define offset_to_ptr(off) \
((void *)((unsigned long)&(off) + (off)))
--
Catalin
On 5 January 2018 at 17:41, Catalin Marinas <[email protected]> wrote:
> On Tue, Jan 02, 2018 at 08:05:44PM +0000, Ard Biesheuvel wrote:
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index 10684b17d0bd..b6d51b4d5ce1 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -3556,9 +3556,16 @@ static void pci_do_fixups(struct pci_dev *dev, struct pci_fixup *f,
>> f->vendor == (u16) PCI_ANY_ID) &&
>> (f->device == dev->device ||
>> f->device == (u16) PCI_ANY_ID)) {
>> - calltime = fixup_debug_start(dev, f->hook);
>> - f->hook(dev);
>> - fixup_debug_report(dev, calltime, f->hook);
>> + void (*hook)(struct pci_dev *dev);
>> +#ifdef CONFIG_HAVE_ARCH_PREL32_RELOCATIONS
>> + hook = (void *)((unsigned long)&f->hook_offset +
>> + f->hook_offset);
>> +#else
>> + hook = f->hook;
>> +#endif
>
> More of a nitpick but I've seen this pattern in several places in your
> code, maybe worth defining a macro (couldn't come up with a better
> name):
>
> #define offset_to_ptr(off) \
> ((void *)((unsigned long)&(off) + (off)))
>
Yeah, good point. Or even
static inline void *offset_to_ptr(const s32 *off)
{
return (void *)((unsigned long)off + *off);
}
On Tue, Jan 02, 2018 at 08:05:46PM +0000, Ard Biesheuvel wrote:
> diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
> index e12d7d096fc0..7b05b404063a 100644
> --- a/arch/arm/include/asm/jump_label.h
> +++ b/arch/arm/include/asm/jump_label.h
> @@ -45,5 +45,32 @@ struct jump_entry {
> jump_label_t key;
> };
>
> +static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
> +{
> + return entry->code;
> +}
> +
> +static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
> +{
> + return (struct static_key *)((unsigned long)entry->key & ~1UL);
> +}
> +
> +static inline bool jump_entry_is_branch(const struct jump_entry *entry)
> +{
> + return (unsigned long)entry->key & 1UL;
> +}
> +
> +static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
> +{
> + return entry->code == 0;
> +}
> +
> +static inline void jump_entry_set_module_init(struct jump_entry *entry)
> +{
> + entry->code = 0;
> +}
> +
> +#define jump_label_swap NULL
Is there any difference between these functions on any of the
architectures touched? Even with the relative offset, arm64 and x86
looked the same to me (well, I may have missed some detail).
--
Catalin
On 5 January 2018 at 17:58, Catalin Marinas <[email protected]> wrote:
> On Tue, Jan 02, 2018 at 08:05:46PM +0000, Ard Biesheuvel wrote:
>> diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
>> index e12d7d096fc0..7b05b404063a 100644
>> --- a/arch/arm/include/asm/jump_label.h
>> +++ b/arch/arm/include/asm/jump_label.h
>> @@ -45,5 +45,32 @@ struct jump_entry {
>> jump_label_t key;
>> };
>>
>> +static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
>> +{
>> + return entry->code;
>> +}
>> +
>> +static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
>> +{
>> + return (struct static_key *)((unsigned long)entry->key & ~1UL);
>> +}
>> +
>> +static inline bool jump_entry_is_branch(const struct jump_entry *entry)
>> +{
>> + return (unsigned long)entry->key & 1UL;
>> +}
>> +
>> +static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
>> +{
>> + return entry->code == 0;
>> +}
>> +
>> +static inline void jump_entry_set_module_init(struct jump_entry *entry)
>> +{
>> + entry->code = 0;
>> +}
>> +
>> +#define jump_label_swap NULL
>
> Is there any difference between these functions on any of the
> architectures touched? Even with the relative offset, arm64 and x86
> looked the same to me (well, I may have missed some detail).
>
No, the latter two are identical everywhere, and the others are the
same modulo absolute vs relative.
The issue is that the struct definition is per-arch so the accessors
should be as well. Perhaps I should introduce two variants two
asm-generic, similar to how we have different flavors of unaligned
accessors.
On Fri, Jan 05, 2018 at 06:01:33PM +0000, Ard Biesheuvel wrote:
> On 5 January 2018 at 17:58, Catalin Marinas <[email protected]> wrote:
> > On Tue, Jan 02, 2018 at 08:05:46PM +0000, Ard Biesheuvel wrote:
> >> diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
> >> index e12d7d096fc0..7b05b404063a 100644
> >> --- a/arch/arm/include/asm/jump_label.h
> >> +++ b/arch/arm/include/asm/jump_label.h
> >> @@ -45,5 +45,32 @@ struct jump_entry {
> >> jump_label_t key;
> >> };
> >>
> >> +static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
> >> +{
> >> + return entry->code;
> >> +}
> >> +
> >> +static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
> >> +{
> >> + return (struct static_key *)((unsigned long)entry->key & ~1UL);
> >> +}
> >> +
> >> +static inline bool jump_entry_is_branch(const struct jump_entry *entry)
> >> +{
> >> + return (unsigned long)entry->key & 1UL;
> >> +}
> >> +
> >> +static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
> >> +{
> >> + return entry->code == 0;
> >> +}
> >> +
> >> +static inline void jump_entry_set_module_init(struct jump_entry *entry)
> >> +{
> >> + entry->code = 0;
> >> +}
> >> +
> >> +#define jump_label_swap NULL
> >
> > Is there any difference between these functions on any of the
> > architectures touched? Even with the relative offset, arm64 and x86
> > looked the same to me (well, I may have missed some detail).
>
> No, the latter two are identical everywhere, and the others are the
> same modulo absolute vs relative.
>
> The issue is that the struct definition is per-arch so the accessors
> should be as well.
Up to this patch, even the jump_entry structure is the same on all
architectures (the jump_label_t type differs).
With relative offset, can you not just define jump_label_t to s32? At a
quick grep in mainline, it doesn't seem to be used outside the structure
definition.
> Perhaps I should introduce two variants two asm-generic, similar to
> how we have different flavors of unaligned accessors.
You could as well define them directly in kernel/jump_label.h or, if
used outside this file, include/linux/jump_label.h.
--
Catalin
On 5 January 2018 at 18:22, Catalin Marinas <[email protected]> wrote:
> On Fri, Jan 05, 2018 at 06:01:33PM +0000, Ard Biesheuvel wrote:
>> On 5 January 2018 at 17:58, Catalin Marinas <[email protected]> wrote:
>> > On Tue, Jan 02, 2018 at 08:05:46PM +0000, Ard Biesheuvel wrote:
>> >> diff --git a/arch/arm/include/asm/jump_label.h b/arch/arm/include/asm/jump_label.h
>> >> index e12d7d096fc0..7b05b404063a 100644
>> >> --- a/arch/arm/include/asm/jump_label.h
>> >> +++ b/arch/arm/include/asm/jump_label.h
>> >> @@ -45,5 +45,32 @@ struct jump_entry {
>> >> jump_label_t key;
>> >> };
>> >>
>> >> +static inline jump_label_t jump_entry_code(const struct jump_entry *entry)
>> >> +{
>> >> + return entry->code;
>> >> +}
>> >> +
>> >> +static inline struct static_key *jump_entry_key(const struct jump_entry *entry)
>> >> +{
>> >> + return (struct static_key *)((unsigned long)entry->key & ~1UL);
>> >> +}
>> >> +
>> >> +static inline bool jump_entry_is_branch(const struct jump_entry *entry)
>> >> +{
>> >> + return (unsigned long)entry->key & 1UL;
>> >> +}
>> >> +
>> >> +static inline bool jump_entry_is_module_init(const struct jump_entry *entry)
>> >> +{
>> >> + return entry->code == 0;
>> >> +}
>> >> +
>> >> +static inline void jump_entry_set_module_init(struct jump_entry *entry)
>> >> +{
>> >> + entry->code = 0;
>> >> +}
>> >> +
>> >> +#define jump_label_swap NULL
>> >
>> > Is there any difference between these functions on any of the
>> > architectures touched? Even with the relative offset, arm64 and x86
>> > looked the same to me (well, I may have missed some detail).
>>
>> No, the latter two are identical everywhere, and the others are the
>> same modulo absolute vs relative.
>>
>> The issue is that the struct definition is per-arch so the accessors
>> should be as well.
>
> Up to this patch, even the jump_entry structure is the same on all
> architectures (the jump_label_t type differs).
>
> With relative offset, can you not just define jump_label_t to s32? At a
> quick grep in mainline, it doesn't seem to be used outside the structure
> definition.
>
I think we can just remove jump_label_t entirely, and replace it with
unsigned long for absolute, and s32 for relative. Maybe I am missing
something, but things like
#ifdef CONFIG_X86_64
typedef u64 jump_label_t;
#else
typedef u32 jump_label_t;
#endif
seem a bit pointless to me anyway.
>> Perhaps I should introduce two variants two asm-generic, similar to
>> how we have different flavors of unaligned accessors.
>
> You could as well define them directly in kernel/jump_label.h or, if
> used outside this file, include/linux/jump_label.h.
>
Perhaps I should define a Kconfig symbol after all for relative jump
labels, and just keep everything in the same file. The question is
whether I should use CONFIG_HAVE_ARCH_PREL32_RELOCATIONS for this as
well.