diff options
| author | Ard Biesheuvel <ardb@kernel.org> | 2022-03-02 12:38:18 +0100 |
|---|---|---|
| committer | Russell King (Oracle) <rmk+kernel@armlinux.org.uk> | 2022-03-07 11:43:12 +0000 |
| commit | 6845d64d51cf69c096176e34864e161429bcb664 (patch) | |
| tree | caba3211fd106abd933746c1b831158f8f59c6c2 /arch/arm/include | |
| parent | 81679376470ef4e070d3ab04b578b2eef1013e46 (diff) | |
ARM: 9184/1: return_address: disable again for CONFIG_ARM_UNWIND=y
Commit 41918ec82eb6 ("ARM: ftrace: enable the graph tracer with the EABI
unwinder") removed the dummy version of return_address() that was
provided for the CONFIG_ARM_UNWIND=y case, on the assumption that the
removal of the kernel_text_address() call from unwind_frame() in the
preceding patch made it safe to do so.
However, this turns out not to be the case: Corentin reports warnings
about suspicious RCU usage and other strange behavior that seems to
originate in the stack unwinding that occurs in return_address().
Given that the function graph tracer (which is what these changes were
enabling for CONFIG_ARM_UNWIND=y builds) does not appear to care about
this distinction, let's revert return_address() to the old state.
Cc: Corentin Labbe <clabbe.montjoie@gmail.com>
Fixes: 41918ec82eb6 ("ARM: ftrace: enable the graph tracer with the EABI unwinder")
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Reported-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Tested-by: Corentin Labbe <clabbe.montjoie@gmail.com>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/ftrace.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/arch/arm/include/asm/ftrace.h b/arch/arm/include/asm/ftrace.h index 5358aad67831..7e9251ca29fe 100644 --- a/arch/arm/include/asm/ftrace.h +++ b/arch/arm/include/asm/ftrace.h @@ -35,8 +35,26 @@ static inline unsigned long ftrace_call_adjust(unsigned long addr) #ifndef __ASSEMBLY__ +#if defined(CONFIG_FRAME_POINTER) && !defined(CONFIG_ARM_UNWIND) +/* + * return_address uses walk_stackframe to do it's work. If both + * CONFIG_FRAME_POINTER=y and CONFIG_ARM_UNWIND=y walk_stackframe uses unwind + * information. For this to work in the function tracer many functions would + * have to be marked with __notrace. So for now just depend on + * !CONFIG_ARM_UNWIND. + */ + void *return_address(unsigned int); +#else + +static inline void *return_address(unsigned int level) +{ + return NULL; +} + +#endif + #define ftrace_return_address(n) return_address(n) #define ARCH_HAS_SYSCALL_MATCH_SYM_NAME |