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samples: ftrace: Save required argument registers in sample trampolines 

The ftrace-direct-too sample traces the handle_mm_fault function whose
signature changed since the introduction of the sample. Since:
commit bce617edec ("mm: do page fault accounting in handle_mm_fault")
handle_mm_fault now has 4 arguments. Therefore, the sample trampoline
should save 4 argument registers.

s390 saves all argument registers already so it does not need a change
but x86_64 needs an extra push and pop.

This also evolves the signature of the tracing function to make it
mirror the signature of the traced function.

Link: https://lkml.kernel.org/r/20230427140700.625241-2-revest@chromium.org

Cc: stable@vger.kernel.org
Fixes: bce617edec ("mm: do page fault accounting in handle_mm_fault")
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Florent Revest 2023-04-27 16:06:59 +02:00 committed by Steven Rostedt (Google)
parent 06c2afb862
commit 8564c31587
1 changed files with 8 additions and 6 deletions
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14
samples/ftrace/ftrace-direct-too.c
View File

@ -5,14 +5,14 @@
#include <linux/ftrace.h>
#include <asm/asm-offsets.h>
extern void my_direct_func(struct vm_area_struct *vma,
unsigned long address, unsigned int flags);
extern void my_direct_func(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, struct pt_regs *regs);
void my_direct_func(struct vm_area_struct *vma,
unsigned long address, unsigned int flags)
void my_direct_func(struct vm_area_struct *vma, unsigned long address,
unsigned int flags, struct pt_regs *regs)
{
trace_printk("handle mm fault vma=%p address=%lx flags=%x\n",
vma, address, flags);
trace_printk("handle mm fault vma=%p address=%lx flags=%x regs=%p\n",
vma, address, flags, regs);
}
extern void my_tramp(void *);
@ -34,7 +34,9 @@ asm (
" pushq %rdi\n"
" pushq %rsi\n"
" pushq %rdx\n"
" pushq %rcx\n"
" call my_direct_func\n"
" popq %rcx\n"
" popq %rdx\n"
" popq %rsi\n"
" popq %rdi\n"