Hi all,
This series bumps the minimum supported version of LLVM for building the
kernel to 13.0.1. The first patch does the bump and all subsequent
patches clean up all the various workarounds and checks for earlier
versions.
Quoting the first patch's commit message for those that were only on CC
for the clean ups:
When __builtin_mul_overflow() has arguments that differ in terms of
signedness and width, LLVM may generate a libcall to __muloti4 because
it performs the checks in terms of 65-bit multiplication. This issue
becomes harder to hit (but still possible) after LLVM 12.0.0, which
includes a special case for matching widths but different signs.
To gain access to this special case, which the kernel can take advantage
of when calls to __muloti4 appear, bump the minimum supported version of
LLVM for building the kernel to 13.0.1. 13.0.1 was chosen because there
is minimal impact to distribution support while allowing a few more
workarounds to be dropped in the kernel source than if 12.0.0 were
chosen. Looking at container images of up to date distribution versions:
archlinux:latest clang version 16.0.6
debian:oldoldstable-slim clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final)
debian:oldstable-slim Debian clang version 11.0.1-2
debian:stable-slim Debian clang version 14.0.6
debian:testing-slim Debian clang version 16.0.6 (19)
debian:unstable-slim Debian clang version 16.0.6 (19)
fedora:38 clang version 16.0.6 (Fedora 16.0.6-3.fc38)
fedora:latest clang version 17.0.6 (Fedora 17.0.6-1.fc39)
fedora:rawhide clang version 17.0.6 (Fedora 17.0.6-1.fc40)
opensuse/leap:latest clang version 15.0.7
opensuse/tumbleweed:latest clang version 17.0.6
ubuntu:focal clang version 10.0.0-4ubuntu1
ubuntu:latest Ubuntu clang version 14.0.0-1ubuntu1.1
ubuntu:rolling Ubuntu clang version 16.0.6 (15)
ubuntu:devel Ubuntu clang version 17.0.6 (3)
The only distribution that gets left behind is Debian Bullseye, as the
default version is 11.0.1; other distributions either have a newer
version than 13.0.1 or one older than the current minimum of 11.0.0.
Debian has easy access to more recent LLVM versions through
apt.llvm.org, so this is not as much of a concern. There are also the
kernel.org LLVM toolchains, which should work with distributions with
glibc 2.28 and newer.
Another benefit of slimming up the number of supported versions of LLVM
for building the kernel is reducing the build capacity needed to support
a matrix that builds with each supported version, which allows a matrix
to reallocate the freed up build capacity towards something else, such
as more configuration combinations.
This passes my build matrix with all supported versions.
This is based on Andrew's mm-nonmm-unstable to avoid trivial conflicts
with my series to update the LLVM links across the repository [1] but I
can easily rebase it to linux-kbuild if Masahiro would rather these
patches go through there (and defer the conflict resolution to the merge
window).
[1]: https://lore.kernel.org/[email protected]/
---
Nathan Chancellor (11):
kbuild: Raise the minimum supported version of LLVM to 13.0.1
Makefile: Drop warn-stack-size plugin opt
x86: Drop stack-alignment plugin opt
ARM: Remove Thumb2 __builtin_thread_pointer workaround for Clang
arm64: Kconfig: Clean up tautological LLVM version checks
powerpc: Kconfig: Remove tautology in CONFIG_COMPAT
riscv: Remove MCOUNT_NAME workaround
riscv: Kconfig: Remove version dependency from CONFIG_CLANG_SUPPORTS_DYNAMIC_FTRACE
fortify: Drop Clang version check for 12.0.1 or newer
lib/Kconfig.debug: Update Clang version check in CONFIG_KCOV
compiler-clang.h: Update __diag_clang() macros for minimum version bump
Documentation/process/changes.rst | 2 +-
Makefile | 8 --------
arch/arm/include/asm/current.h | 8 +-------
arch/arm64/Kconfig | 5 +----
arch/powerpc/Kconfig | 1 -
arch/riscv/Kconfig | 2 --
arch/riscv/include/asm/ftrace.h | 14 ++------------
arch/riscv/kernel/mcount.S | 10 +++++-----
arch/x86/Makefile | 6 ------
include/linux/compiler-clang.h | 8 ++------
lib/Kconfig.debug | 2 +-
scripts/min-tool-version.sh | 2 +-
scripts/recordmcount.pl | 2 +-
security/Kconfig | 2 --
14 files changed, 15 insertions(+), 57 deletions(-)
---
base-commit: 979741ebd48f75ed6d101c7290e3325340d361ff
change-id: 20240124-bump-min-llvm-ver-to-13-0-1-39f84dd36b19
Best regards,
--
Nathan Chancellor <[email protected]>
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, the conditional expression added to
get_current() by commit c1e42efacb9b ("ARM: 9151/1: Thumb2: avoid
__builtin_thread_pointer() on Clang") is always true, as the build will
fail during the configuration stage for older LLVM versions. Remove it,
effectively reverting the aforementioned change.
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
arch/arm/include/asm/current.h | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/arm/include/asm/current.h b/arch/arm/include/asm/current.h
index 1e1178bf176d..5225cb1c803b 100644
--- a/arch/arm/include/asm/current.h
+++ b/arch/arm/include/asm/current.h
@@ -18,18 +18,12 @@ static __always_inline __attribute_const__ struct task_struct *get_current(void)
{
struct task_struct *cur;
-#if __has_builtin(__builtin_thread_pointer) && \
- defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \
- !(defined(CONFIG_THUMB2_KERNEL) && \
- defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
+#if __has_builtin(__builtin_thread_pointer) && defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
/*
* Use the __builtin helper when available - this results in better
* code, especially when using GCC in combination with the per-task
* stack protector, as the compiler will recognize that it needs to
* load the TLS register only once in every function.
- *
- * Clang < 13.0.1 gets this wrong for Thumb2 builds:
- * https://github.com/ClangBuiltLinux/linux/issues/1485
*/
cur = __builtin_thread_pointer();
#elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
--
2.43.0
This reverts commit 6fcb574125e6 ("powerpc: Kconfig: disable
CONFIG_COMPAT for clang < 12").
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, this condition is always true, as the build
will fail during the configuration stage for older LLVM versions. Remove
it.
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
arch/powerpc/Kconfig | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index b9fc064d38d2..86da0d01365a 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -333,7 +333,6 @@ config PANIC_TIMEOUT
config COMPAT
bool "Enable support for 32bit binaries"
depends on PPC64
- depends on !CC_IS_CLANG || CLANG_VERSION >= 120000
default y if !CPU_LITTLE_ENDIAN
select ARCH_WANT_OLD_COMPAT_IPC
select COMPAT_OLD_SIGACTION
--
2.43.0
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, the condition for using _mcount as
MCOUNT_NAME is always true, as the build will fail during the
configuration stage for older LLVM versions. Replace MCOUNT_NAME with
_mcount directly.
This effectively reverts commit 7ce047715030 ("riscv: Workaround mcount
name prior to clang-13").
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
arch/riscv/include/asm/ftrace.h | 14 ++------------
arch/riscv/kernel/mcount.S | 10 +++++-----
scripts/recordmcount.pl | 2 +-
3 files changed, 8 insertions(+), 18 deletions(-)
diff --git a/arch/riscv/include/asm/ftrace.h b/arch/riscv/include/asm/ftrace.h
index 06874fb1311e..cf5b63e789fa 100644
--- a/arch/riscv/include/asm/ftrace.h
+++ b/arch/riscv/include/asm/ftrace.h
@@ -13,19 +13,9 @@
#endif
#define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
-/*
- * Clang prior to 13 had "mcount" instead of "_mcount":
- * https://github.com/llvm/llvm-project/commit/ef58ae86ba778ed7d01cd3f6bd6d08f943abab44
- */
-#if defined(CONFIG_CC_IS_GCC) || CONFIG_CLANG_VERSION >= 130000
-#define MCOUNT_NAME _mcount
-#else
-#define MCOUNT_NAME mcount
-#endif
-
#define ARCH_SUPPORTS_FTRACE_OPS 1
#ifndef __ASSEMBLY__
-void MCOUNT_NAME(void);
+void _mcount(void);
static inline unsigned long ftrace_call_adjust(unsigned long addr)
{
return addr;
@@ -75,7 +65,7 @@ struct dyn_arch_ftrace {
* both auipc and jalr at the same time.
*/
-#define MCOUNT_ADDR ((unsigned long)MCOUNT_NAME)
+#define MCOUNT_ADDR ((unsigned long)_mcount)
#define JALR_SIGN_MASK (0x00000800)
#define JALR_OFFSET_MASK (0x00000fff)
#define AUIPC_OFFSET_MASK (0xfffff000)
diff --git a/arch/riscv/kernel/mcount.S b/arch/riscv/kernel/mcount.S
index d7ec69ac6910..3a42f6287909 100644
--- a/arch/riscv/kernel/mcount.S
+++ b/arch/riscv/kernel/mcount.S
@@ -50,8 +50,8 @@
SYM_TYPED_FUNC_START(ftrace_stub)
#ifdef CONFIG_DYNAMIC_FTRACE
- .global MCOUNT_NAME
- .set MCOUNT_NAME, ftrace_stub
+ .global _mcount
+ .set _mcount, ftrace_stub
#endif
ret
SYM_FUNC_END(ftrace_stub)
@@ -80,7 +80,7 @@ SYM_FUNC_END(return_to_handler)
#endif
#ifndef CONFIG_DYNAMIC_FTRACE
-SYM_FUNC_START(MCOUNT_NAME)
+SYM_FUNC_START(_mcount)
la t4, ftrace_stub
#ifdef CONFIG_FUNCTION_GRAPH_TRACER
la t0, ftrace_graph_return
@@ -126,6 +126,6 @@ SYM_FUNC_START(MCOUNT_NAME)
jalr t5
RESTORE_ABI_STATE
ret
-SYM_FUNC_END(MCOUNT_NAME)
+SYM_FUNC_END(_mcount)
#endif
-EXPORT_SYMBOL(MCOUNT_NAME)
+EXPORT_SYMBOL(_mcount)
diff --git a/scripts/recordmcount.pl b/scripts/recordmcount.pl
index f84df9e383fd..0871b2e92584 100755
--- a/scripts/recordmcount.pl
+++ b/scripts/recordmcount.pl
@@ -352,7 +352,7 @@ if ($arch eq "x86_64") {
$mcount_regex = "^\\s*([0-9a-fA-F]+):.*\\s_mcount\$";
} elsif ($arch eq "riscv") {
$function_regex = "^([0-9a-fA-F]+)\\s+<([^.0-9][0-9a-zA-Z_\\.]+)>:";
- $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_?mcount\$";
+ $mcount_regex = "^\\s*([0-9a-fA-F]+):\\sR_RISCV_CALL(_PLT)?\\s_mcount\$";
$type = ".quad";
$alignment = 2;
} elsif ($arch eq "csky") {
--
2.43.0
The minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1. Update the __diag_clang() macros for this
bump.
Signed-off-by: Nathan Chancellor <[email protected]>
---
include/linux/compiler-clang.h | 8 ++------
1 file changed, 2 insertions(+), 6 deletions(-)
diff --git a/include/linux/compiler-clang.h b/include/linux/compiler-clang.h
index f0a47afef125..49feac0162a5 100644
--- a/include/linux/compiler-clang.h
+++ b/include/linux/compiler-clang.h
@@ -114,11 +114,7 @@
#define __diag_str(s) __diag_str1(s)
#define __diag(s) _Pragma(__diag_str(clang diagnostic s))
-#if CONFIG_CLANG_VERSION >= 110000
-#define __diag_clang_11(s) __diag(s)
-#else
-#define __diag_clang_11(s)
-#endif
+#define __diag_clang_13(s) __diag(s)
#define __diag_ignore_all(option, comment) \
- __diag_clang(11, ignore, option)
+ __diag_clang(13, ignore, option)
--
2.43.0
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, this condition is always true, as the build
will fail during the configuration stage for older LLVM versions. Remove
it.
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
arch/riscv/Kconfig | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 69d24f513922..00edc4ff589c 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -174,8 +174,6 @@ config RISCV
config CLANG_SUPPORTS_DYNAMIC_FTRACE
def_bool CC_IS_CLANG
- # https://github.com/llvm/llvm-project/commit/6ab8927931851bb42b2c93a00801dc499d7d9b1e
- depends on CLANG_VERSION >= 130000
# https://github.com/ClangBuiltLinux/linux/issues/1817
depends on AS_IS_GNU || (AS_IS_LLVM && (LD_IS_LLD || LD_VERSION >= 23600))
--
2.43.0
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, this condition can be changed to just
CONFIG_CC_IS_CLANG, as the build will fail during the configuration
stage for older LLVM versions.
Signed-off-by: Nathan Chancellor <[email protected]>
---
lib/Kconfig.debug | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8f502f15dc7f..1339fb893d71 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2085,7 +2085,7 @@ config KCOV
depends on ARCH_HAS_KCOV
depends on CC_HAS_SANCOV_TRACE_PC || GCC_PLUGINS
depends on !ARCH_WANTS_NO_INSTR || HAVE_NOINSTR_HACK || \
- GCC_VERSION >= 120000 || CLANG_VERSION >= 130000
+ GCC_VERSION >= 120000 || CC_IS_CLANG
select DEBUG_FS
select GCC_PLUGIN_SANCOV if !CC_HAS_SANCOV_TRACE_PC
select OBJTOOL if HAVE_NOINSTR_HACK
--
2.43.0
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, several conditions become tautologies, as
they will always be true because the build will fail during the
configuration stage for older LLVM versions. Drop them, as they are
unnecessary.
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
---
arch/arm64/Kconfig | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 5a8acca4dbf4..cb34e7d780c0 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -383,7 +383,7 @@ config BUILTIN_RETURN_ADDRESS_STRIPS_PAC
bool
# Clang's __builtin_return_adddress() strips the PAC since 12.0.0
# https://github.com/llvm/llvm-project/commit/2a96f47c5ffca84cd774ad402cacd137f4bf45e2
- default y if CC_IS_CLANG && (CLANG_VERSION >= 120000)
+ default y if CC_IS_CLANG
# GCC's __builtin_return_address() strips the PAC since 11.1.0,
# and this was backported to 10.2.0, 9.4.0, 8.5.0, but not earlier
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94891
@@ -1387,7 +1387,6 @@ choice
config CPU_BIG_ENDIAN
bool "Build big-endian kernel"
- depends on !LD_IS_LLD || LLD_VERSION >= 130000
# https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
depends on AS_IS_GNU || AS_VERSION >= 150000
help
@@ -2018,8 +2017,6 @@ config ARM64_BTI_KERNEL
depends on !CC_IS_GCC || GCC_VERSION >= 100100
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671
depends on !CC_IS_GCC
- # https://github.com/llvm/llvm-project/commit/a88c722e687e6780dcd6a58718350dc76fcc4cc9
- depends on !CC_IS_CLANG || CLANG_VERSION >= 120000
depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_ARGS)
help
Build the kernel with Branch Target Identification annotations
--
2.43.0
Now that the minimum supported version of LLVM for building the kernel
has been bumped to 13.0.1, this condition is always true, as the build
will fail during the configuration stage for older LLVM versions. Remove
it.
Signed-off-by: Nathan Chancellor <[email protected]>
---
Cc: [email protected]
Cc: [email protected]
---
security/Kconfig | 2 --
1 file changed, 2 deletions(-)
diff --git a/security/Kconfig b/security/Kconfig
index 606a87c29a01..412e76f1575d 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -142,8 +142,6 @@ config HARDENED_USERCOPY
config FORTIFY_SOURCE
bool "Harden common str/mem functions against buffer overflows"
depends on ARCH_HAS_FORTIFY_SOURCE
- # https://llvm.org/pr41459
- depends on !CC_IS_CLANG || CLANG_VERSION >= 120001
# https://github.com/llvm/llvm-project/issues/53645
depends on !CC_IS_CLANG || !X86_32
help
--
2.43.0
On Thu, Jan 25, 2024 at 03:55:06PM -0700, Nathan Chancellor wrote:
> Hi all,
>
> This series bumps the minimum supported version of LLVM for building the
> kernel to 13.0.1. The first patch does the bump and all subsequent
> patches clean up all the various workarounds and checks for earlier
> versions.
>
> Quoting the first patch's commit message for those that were only on CC
> for the clean ups:
>
> When __builtin_mul_overflow() has arguments that differ in terms of
> signedness and width, LLVM may generate a libcall to __muloti4 because
> it performs the checks in terms of 65-bit multiplication. This issue
> becomes harder to hit (but still possible) after LLVM 12.0.0, which
> includes a special case for matching widths but different signs.
>
> To gain access to this special case, which the kernel can take advantage
> of when calls to __muloti4 appear, bump the minimum supported version of
> LLVM for building the kernel to 13.0.1. 13.0.1 was chosen because there
> is minimal impact to distribution support while allowing a few more
> workarounds to be dropped in the kernel source than if 12.0.0 were
> chosen. Looking at container images of up to date distribution versions:
>
> archlinux:latest clang version 16.0.6
> debian:oldoldstable-slim clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final)
> debian:oldstable-slim Debian clang version 11.0.1-2
> debian:stable-slim Debian clang version 14.0.6
> debian:testing-slim Debian clang version 16.0.6 (19)
> debian:unstable-slim Debian clang version 16.0.6 (19)
> fedora:38 clang version 16.0.6 (Fedora 16.0.6-3.fc38)
> fedora:latest clang version 17.0.6 (Fedora 17.0.6-1.fc39)
> fedora:rawhide clang version 17.0.6 (Fedora 17.0.6-1.fc40)
> opensuse/leap:latest clang version 15.0.7
> opensuse/tumbleweed:latest clang version 17.0.6
> ubuntu:focal clang version 10.0.0-4ubuntu1
> ubuntu:latest Ubuntu clang version 14.0.0-1ubuntu1.1
> ubuntu:rolling Ubuntu clang version 16.0.6 (15)
> ubuntu:devel Ubuntu clang version 17.0.6 (3)
>
> The only distribution that gets left behind is Debian Bullseye, as the
> default version is 11.0.1; other distributions either have a newer
> version than 13.0.1 or one older than the current minimum of 11.0.0.
> Debian has easy access to more recent LLVM versions through
> apt.llvm.org, so this is not as much of a concern. There are also the
> kernel.org LLVM toolchains, which should work with distributions with
> glibc 2.28 and newer.
>
> Another benefit of slimming up the number of supported versions of LLVM
> for building the kernel is reducing the build capacity needed to support
> a matrix that builds with each supported version, which allows a matrix
> to reallocate the freed up build capacity towards something else, such
> as more configuration combinations.
>
> This passes my build matrix with all supported versions.
>
> This is based on Andrew's mm-nonmm-unstable to avoid trivial conflicts
> with my series to update the LLVM links across the repository [1] but I
> can easily rebase it to linux-kbuild if Masahiro would rather these
> patches go through there (and defer the conflict resolution to the merge
> window).
>
> [1]: https://lore.kernel.org/[email protected]/
>
> ---
> Nathan Chancellor (11):
> kbuild: Raise the minimum supported version of LLVM to 13.0.1
> Makefile: Drop warn-stack-size plugin opt
> x86: Drop stack-alignment plugin opt
> ARM: Remove Thumb2 __builtin_thread_pointer workaround for Clang
> arm64: Kconfig: Clean up tautological LLVM version checks
> powerpc: Kconfig: Remove tautology in CONFIG_COMPAT
> riscv: Remove MCOUNT_NAME workaround
> riscv: Kconfig: Remove version dependency from CONFIG_CLANG_SUPPORTS_DYNAMIC_FTRACE
> fortify: Drop Clang version check for 12.0.1 or newer
> lib/Kconfig.debug: Update Clang version check in CONFIG_KCOV
> compiler-clang.h: Update __diag_clang() macros for minimum version bump
>
> Documentation/process/changes.rst | 2 +-
> Makefile | 8 --------
> arch/arm/include/asm/current.h | 8 +-------
> arch/arm64/Kconfig | 5 +----
> arch/powerpc/Kconfig | 1 -
> arch/riscv/Kconfig | 2 --
> arch/riscv/include/asm/ftrace.h | 14 ++------------
> arch/riscv/kernel/mcount.S | 10 +++++-----
> arch/x86/Makefile | 6 ------
> include/linux/compiler-clang.h | 8 ++------
> lib/Kconfig.debug | 2 +-
> scripts/min-tool-version.sh | 2 +-
> scripts/recordmcount.pl | 2 +-
> security/Kconfig | 2 --
> 14 files changed, 15 insertions(+), 57 deletions(-)
> ---
> base-commit: 979741ebd48f75ed6d101c7290e3325340d361ff
> change-id: 20240124-bump-min-llvm-ver-to-13-0-1-39f84dd36b19
>
> Best regards,
> --
> Nathan Chancellor <[email protected]>
>
Yes, please. :) This looks reasonable -- I appreciate the review of
default Clang versions across distros!
Reviewed-by: Kees Cook <[email protected]>
--
Kees Cook
On Thu, Jan 25, 2024 at 03:55:15PM -0700, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 13.0.1, this condition is always true, as the build
> will fail during the configuration stage for older LLVM versions. Remove
> it.
>
> Signed-off-by: Nathan Chancellor <[email protected]>
Acked-by: Kees Cook <[email protected]>
--
Kees Cook
On Thu, 25 Jan 2024 at 23:56, Nathan Chancellor <[email protected]> wrote:
>
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 13.0.1, the conditional expression added to
> get_current() by commit c1e42efacb9b ("ARM: 9151/1: Thumb2: avoid
> __builtin_thread_pointer() on Clang") is always true, as the build will
> fail during the configuration stage for older LLVM versions. Remove it,
> effectively reverting the aforementioned change.
>
> Signed-off-by: Nathan Chancellor <[email protected]>
Reviewed-by: Ard Biesheuvel <[email protected]>
> ---
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> arch/arm/include/asm/current.h | 8 +-------
> 1 file changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/arch/arm/include/asm/current.h b/arch/arm/include/asm/current.h
> index 1e1178bf176d..5225cb1c803b 100644
> --- a/arch/arm/include/asm/current.h
> +++ b/arch/arm/include/asm/current.h
> @@ -18,18 +18,12 @@ static __always_inline __attribute_const__ struct task_struct *get_current(void)
> {
> struct task_struct *cur;
>
> -#if __has_builtin(__builtin_thread_pointer) && \
> - defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) && \
> - !(defined(CONFIG_THUMB2_KERNEL) && \
> - defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 130001)
> +#if __has_builtin(__builtin_thread_pointer) && defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO)
> /*
> * Use the __builtin helper when available - this results in better
> * code, especially when using GCC in combination with the per-task
> * stack protector, as the compiler will recognize that it needs to
> * load the TLS register only once in every function.
> - *
> - * Clang < 13.0.1 gets this wrong for Thumb2 builds:
> - * https://github.com/ClangBuiltLinux/linux/issues/1485
> */
> cur = __builtin_thread_pointer();
> #elif defined(CONFIG_CURRENT_POINTER_IN_TPIDRURO) || defined(CONFIG_SMP)
>
> --
> 2.43.0
>
On Thu, Jan 25, 2024 at 03:55:11PM -0700, Nathan Chancellor wrote:
> Now that the minimum supported version of LLVM for building the kernel
> has been bumped to 13.0.1, several conditions become tautologies, as
> they will always be true because the build will fail during the
> configuration stage for older LLVM versions. Drop them, as they are
> unnecessary.
>
> Signed-off-by: Nathan Chancellor <[email protected]>
> ---
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> Cc: [email protected]
> ---
> arch/arm64/Kconfig | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 5a8acca4dbf4..cb34e7d780c0 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -383,7 +383,7 @@ config BUILTIN_RETURN_ADDRESS_STRIPS_PAC
> bool
> # Clang's __builtin_return_adddress() strips the PAC since 12.0.0
> # https://github.com/llvm/llvm-project/commit/2a96f47c5ffca84cd774ad402cacd137f4bf45e2
> - default y if CC_IS_CLANG && (CLANG_VERSION >= 120000)
> + default y if CC_IS_CLANG
> # GCC's __builtin_return_address() strips the PAC since 11.1.0,
> # and this was backported to 10.2.0, 9.4.0, 8.5.0, but not earlier
> # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94891
> @@ -1387,7 +1387,6 @@ choice
>
> config CPU_BIG_ENDIAN
> bool "Build big-endian kernel"
> - depends on !LD_IS_LLD || LLD_VERSION >= 130000
> # https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
We can delete the URL here, since that was just to describe why this depended
upon LLVM 13+; it's weird for it to sit here on its own.
The URL above for __builtin_return_address() can stay or go; it may as well
stay since we have the comment aboout LLvm 12+ above it.
With that:
Acked-by: Mark Rutland <[email protected]>
Mark.
> depends on AS_IS_GNU || AS_VERSION >= 150000
> help
> @@ -2018,8 +2017,6 @@ config ARM64_BTI_KERNEL
> depends on !CC_IS_GCC || GCC_VERSION >= 100100
> # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671
> depends on !CC_IS_GCC
> - # https://github.com/llvm/llvm-project/commit/a88c722e687e6780dcd6a58718350dc76fcc4cc9
> - depends on !CC_IS_CLANG || CLANG_VERSION >= 120000
> depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_ARGS)
> help
> Build the kernel with Branch Target Identification annotations
>
> --
> 2.43.0
>
On Fri, Jan 26, 2024 at 12:59:55PM +0000, Mark Rutland wrote:
> On Thu, Jan 25, 2024 at 03:55:11PM -0700, Nathan Chancellor wrote:
> > Now that the minimum supported version of LLVM for building the kernel
> > has been bumped to 13.0.1, several conditions become tautologies, as
> > they will always be true because the build will fail during the
> > configuration stage for older LLVM versions. Drop them, as they are
> > unnecessary.
> >
> > Signed-off-by: Nathan Chancellor <[email protected]>
> > ---
> > Cc: [email protected]
> > Cc: [email protected]
> > Cc: [email protected]
> > Cc: [email protected]
> > ---
> > arch/arm64/Kconfig | 5 +----
> > 1 file changed, 1 insertion(+), 4 deletions(-)
> >
> > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> > index 5a8acca4dbf4..cb34e7d780c0 100644
> > --- a/arch/arm64/Kconfig
> > +++ b/arch/arm64/Kconfig
> > @@ -383,7 +383,7 @@ config BUILTIN_RETURN_ADDRESS_STRIPS_PAC
> > bool
> > # Clang's __builtin_return_adddress() strips the PAC since 12.0.0
> > # https://github.com/llvm/llvm-project/commit/2a96f47c5ffca84cd774ad402cacd137f4bf45e2
> > - default y if CC_IS_CLANG && (CLANG_VERSION >= 120000)
> > + default y if CC_IS_CLANG
> > # GCC's __builtin_return_address() strips the PAC since 11.1.0,
> > # and this was backported to 10.2.0, 9.4.0, 8.5.0, but not earlier
> > # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94891
> > @@ -1387,7 +1387,6 @@ choice
> >
> > config CPU_BIG_ENDIAN
> > bool "Build big-endian kernel"
> > - depends on !LD_IS_LLD || LLD_VERSION >= 130000
> > # https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
>
> We can delete the URL here, since that was just to describe why this depended
> upon LLVM 13+; it's weird for it to sit here on its own.
I think this is the URL for the fix for the problem brought up by
commit 146a15b87335 ("arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM
IAS 15.x or newer"), so I think it should stay? It does not look like I
ever added a link or context for the LLD line, I definitely should have.
> The URL above for __builtin_return_address() can stay or go; it may as well
> stay since we have the comment aboout LLvm 12+ above it.
That's the conclusion I came to as well.
Thanks a lot for taking a look!
Cheers,
Nathan
> With that:
>
> Acked-by: Mark Rutland <[email protected]>
>
> Mark.
>
> > depends on AS_IS_GNU || AS_VERSION >= 150000
> > help
> > @@ -2018,8 +2017,6 @@ config ARM64_BTI_KERNEL
> > depends on !CC_IS_GCC || GCC_VERSION >= 100100
> > # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106671
> > depends on !CC_IS_GCC
> > - # https://github.com/llvm/llvm-project/commit/a88c722e687e6780dcd6a58718350dc76fcc4cc9
> > - depends on !CC_IS_CLANG || CLANG_VERSION >= 120000
> > depends on (!FUNCTION_GRAPH_TRACER || DYNAMIC_FTRACE_WITH_ARGS)
> > help
> > Build the kernel with Branch Target Identification annotations
> >
> > --
> > 2.43.0
> >
>
On Fri, Jan 26, 2024 at 09:10:25AM -0700, Nathan Chancellor wrote:
> On Fri, Jan 26, 2024 at 12:59:55PM +0000, Mark Rutland wrote:
> > On Thu, Jan 25, 2024 at 03:55:11PM -0700, Nathan Chancellor wrote:
> > > config CPU_BIG_ENDIAN
> > > bool "Build big-endian kernel"
> > > - depends on !LD_IS_LLD || LLD_VERSION >= 130000
> > > # https://github.com/llvm/llvm-project/commit/1379b150991f70a5782e9a143c2ba5308da1161c
> >
> > We can delete the URL here, since that was just to describe why this depended
> > upon LLVM 13+; it's weird for it to sit here on its own.
>
> I think this is the URL for the fix for the problem brought up by
> commit 146a15b87335 ("arm64: Restrict CPU_BIG_ENDIAN to GNU as or LLVM
> IAS 15.x or newer"), so I think it should stay? It does not look like I
> ever added a link or context for the LLD line, I definitely should have.
Whoops; I clearly misread that, and yes it should stay.
Sorry about that; for the patch as-is:
Acked-by: Mark Rutland <[email protected]>
Mark.
Hello:
This series was applied to riscv/linux.git (fixes)
by Andrew Morton <[email protected]>:
On Thu, 25 Jan 2024 15:55:06 -0700 you wrote:
> Hi all,
>
> This series bumps the minimum supported version of LLVM for building the
> kernel to 13.0.1. The first patch does the bump and all subsequent
> patches clean up all the various workarounds and checks for earlier
> versions.
>
> [...]
Here is the summary with links:
- [07/11] riscv: Remove MCOUNT_NAME workaround
https://git.kernel.org/riscv/c/de5f3984664e
- [08/11] riscv: Kconfig: Remove version dependency from CONFIG_CLANG_SUPPORTS_DYNAMIC_FTRACE
https://git.kernel.org/riscv/c/a38d97181271
You are awesome, thank you!
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