This patch series is present in v5.14 and fixes warnings seen at insmod
with FTRACE and MODULE_PLTS enabled on ARM/Linux.
Alex Sverdlin (3):
ARM: 9077/1: PLT: Move struct plt_entries definition to header
ARM: 9078/1: Add warn suppress parameter to arm_gen_branch_link()
ARM: 9079/1: ftrace: Add MODULE_PLTS support
arch/arm/include/asm/ftrace.h | 3 +++
arch/arm/include/asm/insn.h | 8 +++---
arch/arm/include/asm/module.h | 10 +++++++
arch/arm/kernel/ftrace.c | 46 ++++++++++++++++++++++++++------
arch/arm/kernel/insn.c | 19 +++++++-------
arch/arm/kernel/module-plts.c | 49 +++++++++++++++++++++++++++--------
6 files changed, 103 insertions(+), 32 deletions(-)
--
2.25.1
From: Alex Sverdlin <[email protected]>
commit 4e271701c17dee70c6e1351c4d7d42e70405c6a9 upstream upstream
No functional change, later it will be re-used in several files.
Signed-off-by: Alexander Sverdlin <[email protected]>
Signed-off-by: Russell King <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
---
arch/arm/include/asm/module.h | 9 +++++++++
arch/arm/kernel/module-plts.c | 9 ---------
2 files changed, 9 insertions(+), 9 deletions(-)
diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index 4b0df09cbe67..09b9ad55b83d 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -19,6 +19,15 @@ enum {
};
#endif
+#define PLT_ENT_STRIDE L1_CACHE_BYTES
+#define PLT_ENT_COUNT (PLT_ENT_STRIDE / sizeof(u32))
+#define PLT_ENT_SIZE (sizeof(struct plt_entries) / PLT_ENT_COUNT)
+
+struct plt_entries {
+ u32 ldr[PLT_ENT_COUNT];
+ u32 lit[PLT_ENT_COUNT];
+};
+
struct mod_plt_sec {
struct elf32_shdr *plt;
int plt_count;
diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
index 6e626abaefc5..d330e9ec2de3 100644
--- a/arch/arm/kernel/module-plts.c
+++ b/arch/arm/kernel/module-plts.c
@@ -12,10 +12,6 @@
#include <asm/cache.h>
#include <asm/opcodes.h>
-#define PLT_ENT_STRIDE L1_CACHE_BYTES
-#define PLT_ENT_COUNT (PLT_ENT_STRIDE / sizeof(u32))
-#define PLT_ENT_SIZE (sizeof(struct plt_entries) / PLT_ENT_COUNT)
-
#ifdef CONFIG_THUMB2_KERNEL
#define PLT_ENT_LDR __opcode_to_mem_thumb32(0xf8dff000 | \
(PLT_ENT_STRIDE - 4))
@@ -24,11 +20,6 @@
(PLT_ENT_STRIDE - 8))
#endif
-struct plt_entries {
- u32 ldr[PLT_ENT_COUNT];
- u32 lit[PLT_ENT_COUNT];
-};
-
static bool in_init(const struct module *mod, unsigned long loc)
{
return loc - (u32)mod->init_layout.base < mod->init_layout.size;
--
2.25.1
From: Alex Sverdlin <[email protected]>
commit 890cb057a46d323fd8c77ebecb6485476614cd21 upstream
Will be used in the following patch. No functional change.
Signed-off-by: Alexander Sverdlin <[email protected]>
Signed-off-by: Russell King <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
---
arch/arm/include/asm/insn.h | 8 ++++----
arch/arm/kernel/ftrace.c | 2 +-
arch/arm/kernel/insn.c | 19 ++++++++++---------
3 files changed, 15 insertions(+), 14 deletions(-)
diff --git a/arch/arm/include/asm/insn.h b/arch/arm/include/asm/insn.h
index f20e08ac85ae..5475cbf9fb6b 100644
--- a/arch/arm/include/asm/insn.h
+++ b/arch/arm/include/asm/insn.h
@@ -13,18 +13,18 @@ arm_gen_nop(void)
}
unsigned long
-__arm_gen_branch(unsigned long pc, unsigned long addr, bool link);
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn);
static inline unsigned long
arm_gen_branch(unsigned long pc, unsigned long addr)
{
- return __arm_gen_branch(pc, addr, false);
+ return __arm_gen_branch(pc, addr, false, true);
}
static inline unsigned long
-arm_gen_branch_link(unsigned long pc, unsigned long addr)
+arm_gen_branch_link(unsigned long pc, unsigned long addr, bool warn)
{
- return __arm_gen_branch(pc, addr, true);
+ return __arm_gen_branch(pc, addr, true, warn);
}
#endif
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 9a79ef6b1876..61de8172a044 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -70,7 +70,7 @@ int ftrace_arch_code_modify_post_process(void)
static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
{
- return arm_gen_branch_link(pc, addr);
+ return arm_gen_branch_link(pc, addr, true);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
diff --git a/arch/arm/kernel/insn.c b/arch/arm/kernel/insn.c
index 2e844b70386b..db0acbb7d7a0 100644
--- a/arch/arm/kernel/insn.c
+++ b/arch/arm/kernel/insn.c
@@ -3,8 +3,9 @@
#include <linux/kernel.h>
#include <asm/opcodes.h>
-static unsigned long
-__arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
+static unsigned long __arm_gen_branch_thumb2(unsigned long pc,
+ unsigned long addr, bool link,
+ bool warn)
{
unsigned long s, j1, j2, i1, i2, imm10, imm11;
unsigned long first, second;
@@ -12,7 +13,7 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
offset = (long)addr - (long)(pc + 4);
if (offset < -16777216 || offset > 16777214) {
- WARN_ON_ONCE(1);
+ WARN_ON_ONCE(warn);
return 0;
}
@@ -33,8 +34,8 @@ __arm_gen_branch_thumb2(unsigned long pc, unsigned long addr, bool link)
return __opcode_thumb32_compose(first, second);
}
-static unsigned long
-__arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
+static unsigned long __arm_gen_branch_arm(unsigned long pc, unsigned long addr,
+ bool link, bool warn)
{
unsigned long opcode = 0xea000000;
long offset;
@@ -44,7 +45,7 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
offset = (long)addr - (long)(pc + 8);
if (unlikely(offset < -33554432 || offset > 33554428)) {
- WARN_ON_ONCE(1);
+ WARN_ON_ONCE(warn);
return 0;
}
@@ -54,10 +55,10 @@ __arm_gen_branch_arm(unsigned long pc, unsigned long addr, bool link)
}
unsigned long
-__arm_gen_branch(unsigned long pc, unsigned long addr, bool link)
+__arm_gen_branch(unsigned long pc, unsigned long addr, bool link, bool warn)
{
if (IS_ENABLED(CONFIG_THUMB2_KERNEL))
- return __arm_gen_branch_thumb2(pc, addr, link);
+ return __arm_gen_branch_thumb2(pc, addr, link, warn);
else
- return __arm_gen_branch_arm(pc, addr, link);
+ return __arm_gen_branch_arm(pc, addr, link, warn);
}
--
2.25.1
From: Alex Sverdlin <[email protected]>
commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream
Teach ftrace_make_call() and ftrace_make_nop() about PLTs.
Teach PLT code about FTRACE and all its callbacks.
Otherwise the following might happen:
------------[ cut here ]------------
WARNING: CPU: 14 PID: 2265 at .../arch/arm/kernel/insn.c:14 __arm_gen_branch+0x83/0x8c()
...
Hardware name: LSI Axxia AXM55XX
[<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
[<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
[<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
[<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
[<c03218f3>] (warn_slowpath_null) from [<c03143cf>] (__arm_gen_branch+0x83/0x8c)
[<c03143cf>] (__arm_gen_branch) from [<c0314337>] (ftrace_make_nop+0xf/0x24)
[<c0314337>] (ftrace_make_nop) from [<c038ebcb>] (ftrace_process_locs+0x27b/0x3e8)
[<c038ebcb>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
[<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
[<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
---[ end trace e1b64ced7a89adcc ]---
------------[ cut here ]------------
WARNING: CPU: 14 PID: 2265 at .../kernel/trace/ftrace.c:1979 ftrace_bug+0x1b1/0x234()
...
Hardware name: LSI Axxia AXM55XX
[<c0314a49>] (unwind_backtrace) from [<c03115e9>] (show_stack+0x11/0x14)
[<c03115e9>] (show_stack) from [<c0519f51>] (dump_stack+0x81/0xa8)
[<c0519f51>] (dump_stack) from [<c032185d>] (warn_slowpath_common+0x69/0x90)
[<c032185d>] (warn_slowpath_common) from [<c03218f3>] (warn_slowpath_null+0x17/0x1c)
[<c03218f3>] (warn_slowpath_null) from [<c038e87d>] (ftrace_bug+0x1b1/0x234)
[<c038e87d>] (ftrace_bug) from [<c038ebd5>] (ftrace_process_locs+0x285/0x3e8)
[<c038ebd5>] (ftrace_process_locs) from [<c0378d79>] (load_module+0x11e9/0x1a44)
[<c0378d79>] (load_module) from [<c037974d>] (SyS_finit_module+0x59/0x84)
[<c037974d>] (SyS_finit_module) from [<c030e981>] (ret_fast_syscall+0x1/0x18)
---[ end trace e1b64ced7a89adcd ]---
ftrace failed to modify [<e9ef7006>] 0xe9ef7006
actual: 02:f0:3b:fa
ftrace record flags: 0
(0) expected tramp: c0314265
Signed-off-by: Alexander Sverdlin <[email protected]>
Signed-off-by: Russell King <[email protected]>
Signed-off-by: Florian Fainelli <[email protected]>
---
arch/arm/include/asm/ftrace.h | 3 +++
arch/arm/include/asm/module.h | 1 +
arch/arm/kernel/ftrace.c | 46 +++++++++++++++++++++++++++++------
arch/arm/kernel/module-plts.c | 44 ++++++++++++++++++++++++++++++---
4 files changed, 82 insertions(+), 12 deletions(-)
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h
index 48ec1d0337da..a4dbac07e4ef 100644
--- a/arch/arm/include/asm/ftrace.h
+++ b/arch/arm/include/asm/ftrace.h
@@ -15,6 +15,9 @@ extern void __gnu_mcount_nc(void);
#ifdef CONFIG_DYNAMIC_FTRACE
struct dyn_arch_ftrace {
+#ifdef CONFIG_ARM_MODULE_PLTS
+ struct module *mod;
+#endif
};
static inline unsigned long ftrace_call_adjust(unsigned long addr)
diff --git a/arch/arm/include/asm/module.h b/arch/arm/include/asm/module.h
index 09b9ad55b83d..cfffae67c04e 100644
--- a/arch/arm/include/asm/module.h
+++ b/arch/arm/include/asm/module.h
@@ -30,6 +30,7 @@ struct plt_entries {
struct mod_plt_sec {
struct elf32_shdr *plt;
+ struct plt_entries *plt_ent;
int plt_count;
};
diff --git a/arch/arm/kernel/ftrace.c b/arch/arm/kernel/ftrace.c
index 61de8172a044..3c83b5d29697 100644
--- a/arch/arm/kernel/ftrace.c
+++ b/arch/arm/kernel/ftrace.c
@@ -68,9 +68,10 @@ int ftrace_arch_code_modify_post_process(void)
return 0;
}
-static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr)
+static unsigned long ftrace_call_replace(unsigned long pc, unsigned long addr,
+ bool warn)
{
- return arm_gen_branch_link(pc, addr, true);
+ return arm_gen_branch_link(pc, addr, warn);
}
static int ftrace_modify_code(unsigned long pc, unsigned long old,
@@ -104,14 +105,14 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
int ret;
pc = (unsigned long)&ftrace_call;
- new = ftrace_call_replace(pc, (unsigned long)func);
+ new = ftrace_call_replace(pc, (unsigned long)func, true);
ret = ftrace_modify_code(pc, 0, new, false);
#ifdef CONFIG_DYNAMIC_FTRACE_WITH_REGS
if (!ret) {
pc = (unsigned long)&ftrace_regs_call;
- new = ftrace_call_replace(pc, (unsigned long)func);
+ new = ftrace_call_replace(pc, (unsigned long)func, true);
ret = ftrace_modify_code(pc, 0, new, false);
}
@@ -124,10 +125,22 @@ int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr)
{
unsigned long new, old;
unsigned long ip = rec->ip;
+ unsigned long aaddr = adjust_address(rec, addr);
+ struct module *mod = NULL;
+
+#ifdef CONFIG_ARM_MODULE_PLTS
+ mod = rec->arch.mod;
+#endif
old = ftrace_nop_replace(rec);
- new = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_call_replace(ip, aaddr, !mod);
+#ifdef CONFIG_ARM_MODULE_PLTS
+ if (!new && mod) {
+ aaddr = get_module_plt(mod, ip, aaddr);
+ new = ftrace_call_replace(ip, aaddr, true);
+ }
+#endif
return ftrace_modify_code(rec->ip, old, new, true);
}
@@ -140,9 +153,9 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
unsigned long new, old;
unsigned long ip = rec->ip;
- old = ftrace_call_replace(ip, adjust_address(rec, old_addr));
+ old = ftrace_call_replace(ip, adjust_address(rec, old_addr), true);
- new = ftrace_call_replace(ip, adjust_address(rec, addr));
+ new = ftrace_call_replace(ip, adjust_address(rec, addr), true);
return ftrace_modify_code(rec->ip, old, new, true);
}
@@ -152,12 +165,29 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
int ftrace_make_nop(struct module *mod,
struct dyn_ftrace *rec, unsigned long addr)
{
+ unsigned long aaddr = adjust_address(rec, addr);
unsigned long ip = rec->ip;
unsigned long old;
unsigned long new;
int ret;
- old = ftrace_call_replace(ip, adjust_address(rec, addr));
+#ifdef CONFIG_ARM_MODULE_PLTS
+ /* mod is only supplied during module loading */
+ if (!mod)
+ mod = rec->arch.mod;
+ else
+ rec->arch.mod = mod;
+#endif
+
+ old = ftrace_call_replace(ip, aaddr,
+ !IS_ENABLED(CONFIG_ARM_MODULE_PLTS) || !mod);
+#ifdef CONFIG_ARM_MODULE_PLTS
+ if (!old && mod) {
+ aaddr = get_module_plt(mod, ip, aaddr);
+ old = ftrace_call_replace(ip, aaddr, true);
+ }
+#endif
+
new = ftrace_nop_replace(rec);
ret = ftrace_modify_code(ip, old, new, true);
diff --git a/arch/arm/kernel/module-plts.c b/arch/arm/kernel/module-plts.c
index d330e9ec2de3..a0524ad84e4d 100644
--- a/arch/arm/kernel/module-plts.c
+++ b/arch/arm/kernel/module-plts.c
@@ -4,6 +4,7 @@
*/
#include <linux/elf.h>
+#include <linux/ftrace.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sort.h>
@@ -20,19 +21,52 @@
(PLT_ENT_STRIDE - 8))
#endif
+static const u32 fixed_plts[] = {
+#ifdef CONFIG_FUNCTION_TRACER
+ FTRACE_ADDR,
+ MCOUNT_ADDR,
+#endif
+};
+
static bool in_init(const struct module *mod, unsigned long loc)
{
return loc - (u32)mod->init_layout.base < mod->init_layout.size;
}
+static void prealloc_fixed(struct mod_plt_sec *pltsec, struct plt_entries *plt)
+{
+ int i;
+
+ if (!ARRAY_SIZE(fixed_plts) || pltsec->plt_count)
+ return;
+ pltsec->plt_count = ARRAY_SIZE(fixed_plts);
+
+ for (i = 0; i < ARRAY_SIZE(plt->ldr); ++i)
+ plt->ldr[i] = PLT_ENT_LDR;
+
+ BUILD_BUG_ON(sizeof(fixed_plts) > sizeof(plt->lit));
+ memcpy(plt->lit, fixed_plts, sizeof(fixed_plts));
+}
+
u32 get_module_plt(struct module *mod, unsigned long loc, Elf32_Addr val)
{
struct mod_plt_sec *pltsec = !in_init(mod, loc) ? &mod->arch.core :
&mod->arch.init;
+ struct plt_entries *plt;
+ int idx;
+
+ /* cache the address, ELF header is available only during module load */
+ if (!pltsec->plt_ent)
+ pltsec->plt_ent = (struct plt_entries *)pltsec->plt->sh_addr;
+ plt = pltsec->plt_ent;
- struct plt_entries *plt = (struct plt_entries *)pltsec->plt->sh_addr;
- int idx = 0;
+ prealloc_fixed(pltsec, plt);
+
+ for (idx = 0; idx < ARRAY_SIZE(fixed_plts); ++idx)
+ if (plt->lit[idx] == val)
+ return (u32)&plt->ldr[idx];
+ idx = 0;
/*
* Look for an existing entry pointing to 'val'. Given that the
* relocations are sorted, this will be the last entry we allocated.
@@ -180,8 +214,8 @@ static unsigned int count_plts(const Elf32_Sym *syms, Elf32_Addr base,
int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
char *secstrings, struct module *mod)
{
- unsigned long core_plts = 0;
- unsigned long init_plts = 0;
+ unsigned long core_plts = ARRAY_SIZE(fixed_plts);
+ unsigned long init_plts = ARRAY_SIZE(fixed_plts);
Elf32_Shdr *s, *sechdrs_end = sechdrs + ehdr->e_shnum;
Elf32_Sym *syms = NULL;
@@ -236,6 +270,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
mod->arch.core.plt->sh_size = round_up(core_plts * PLT_ENT_SIZE,
sizeof(struct plt_entries));
mod->arch.core.plt_count = 0;
+ mod->arch.core.plt_ent = NULL;
mod->arch.init.plt->sh_type = SHT_NOBITS;
mod->arch.init.plt->sh_flags = SHF_EXECINSTR | SHF_ALLOC;
@@ -243,6 +278,7 @@ int module_frob_arch_sections(Elf_Ehdr *ehdr, Elf_Shdr *sechdrs,
mod->arch.init.plt->sh_size = round_up(init_plts * PLT_ENT_SIZE,
sizeof(struct plt_entries));
mod->arch.init.plt_count = 0;
+ mod->arch.init.plt_ent = NULL;
pr_debug("%s: plt=%x, init.plt=%x\n", __func__,
mod->arch.core.plt->sh_size, mod->arch.init.plt->sh_size);
--
2.25.1
Hello Florian,
On 22/09/2021 04:39, Florian Fainelli wrote:
> From: Alex Sverdlin <[email protected]>
>
> commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream
>
> Teach ftrace_make_call() and ftrace_make_nop() about PLTs.
> Teach PLT code about FTRACE and all its callbacks.
sorry for inconvenience, but I'd propose to add 6fa630bf473827ae
"ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE"
to all series on this topic, because of the below chunk which might
lead to build issues on some exotic configurations.
Link: https://lists.01.org/hyperkitty/list/[email protected]/thread/ZUVCQBHDMFVR7CCB7JPESLJEWERZDJ3T/
> --- a/arch/arm/kernel/module-plts.c
> +++ b/arch/arm/kernel/module-plts.c
> @@ -20,19 +21,52 @@
> (PLT_ENT_STRIDE - 8))
> #endif
>
> +static const u32 fixed_plts[] = {
> +#ifdef CONFIG_FUNCTION_TRACER
> + FTRACE_ADDR,
> + MCOUNT_ADDR,
> +#endif
> +};
> +
> static bool in_init(const struct module *mod, unsigned long loc)
> {
> return loc - (u32)mod->init_layout.base < mod->init_layout.size;
--
Best regards,
Alexander Sverdlin.
Hi Alex,
On 9/21/21 11:53 PM, Alexander Sverdlin wrote:
> Hello Florian,
>
> On 22/09/2021 04:39, Florian Fainelli wrote:
>> From: Alex Sverdlin <[email protected]>
>>
>> commit 79f32b221b18c15a98507b101ef4beb52444cc6f upstream
>>
>> Teach ftrace_make_call() and ftrace_make_nop() about PLTs.
>> Teach PLT code about FTRACE and all its callbacks.
>
> sorry for inconvenience, but I'd propose to add 6fa630bf473827ae
> "ARM: 9098/1: ftrace: MODULE_PLT: Fix build problem without DYNAMIC_FTRACE"
> to all series on this topic, because of the below chunk which might
> lead to build issues on some exotic configurations.
>
> Link: https://lists.01.org/hyperkitty/list/[email protected]/thread/ZUVCQBHDMFVR7CCB7JPESLJEWERZDJ3T/
Good point, missed that one, I will add it to the stable submission and
resend, thanks!
--
Florian