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SubjectRe: Re: [RFC][PATCH 2/4 v4] ftrace/x86: Add save_regs for i386 function calls
(2012/07/19 0:59), Steven Rostedt wrote:
> On Fri, 2012-07-13 at 14:47 -0400, Steven Rostedt wrote:
>
> Masami, can you give your Reviewed-by tag for this version? Or is there
> something else needing to be fixed?

No, that is OK for me. I've just missed that...

Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>

Thank you!

>
> Thanks!
>
> -- Steve
>
>> From: Steven Rostedt <srostedt@redhat.com>
>> Date: Tue, 5 Jun 2012 20:00:11 -0400
>> Subject: [PATCH] ftrace/x86: Add save_regs for i386 function calls
>>
>> Add saving full regs for function tracing on i386.
>> The saving of regs was influenced by patches sent out by
>> Masami Hiramatsu.
>>
>> Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
>> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>> ---
>> arch/x86/include/asm/ftrace.h | 2 -
>> arch/x86/kernel/entry_32.S | 68 +++++++++++++++++++++++++++++++++++++++++
>> arch/x86/kernel/ftrace.c | 4 --
>> 3 files changed, 68 insertions(+), 6 deletions(-)
>>
>> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
>> index a847501..a6cae0c 100644
>> --- a/arch/x86/include/asm/ftrace.h
>> +++ b/arch/x86/include/asm/ftrace.h
>> @@ -40,10 +40,8 @@
>>
>> #ifdef CONFIG_DYNAMIC_FTRACE
>> #define ARCH_SUPPORTS_FTRACE_OPS 1
>> -#ifdef CONFIG_X86_64
>> #define ARCH_SUPPORTS_FTRACE_SAVE_REGS
>> #endif
>> -#endif
>>
>> #ifndef __ASSEMBLY__
>> extern void mcount(void);
>> diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
>> index 5da11d1..46caa56 100644
>> --- a/arch/x86/kernel/entry_32.S
>> +++ b/arch/x86/kernel/entry_32.S
>> @@ -1123,6 +1123,7 @@ ftrace_call:
>> popl %edx
>> popl %ecx
>> popl %eax
>> +ftrace_ret:
>> #ifdef CONFIG_FUNCTION_GRAPH_TRACER
>> .globl ftrace_graph_call
>> ftrace_graph_call:
>> @@ -1134,6 +1135,73 @@ ftrace_stub:
>> ret
>> END(ftrace_caller)
>>
>> +ENTRY(ftrace_regs_caller)
>> + pushf /* push flags before compare (in cs location) */
>> + cmpl $0, function_trace_stop
>> + jne ftrace_restore_flags
>> +
>> + /*
>> + * i386 does not save SS and ESP when coming from kernel.
>> + * Instead, to get sp, &regs->sp is used (see ptrace.h).
>> + * Unfortunately, that means eflags must be at the same location
>> + * as the current return ip is. We move the return ip into the
>> + * ip location, and move flags into the return ip location.
>> + */
>> + pushl 4(%esp) /* save return ip into ip slot */
>> + subl $MCOUNT_INSN_SIZE, (%esp) /* Adjust ip */
>> +
>> + pushl $0 /* Load 0 into orig_ax */
>> + pushl %gs
>> + pushl %fs
>> + pushl %es
>> + pushl %ds
>> + pushl %eax
>> + pushl %ebp
>> + pushl %edi
>> + pushl %esi
>> + pushl %edx
>> + pushl %ecx
>> + pushl %ebx
>> +
>> + movl 13*4(%esp), %eax /* Get the saved flags */
>> + movl %eax, 14*4(%esp) /* Move saved flags into regs->flags location */
>> + /* clobbering return ip */
>> + movl $__KERNEL_CS,13*4(%esp)
>> +
>> + movl 12*4(%esp), %eax /* Load ip (1st parameter) */
>> + movl 0x4(%ebp), %edx /* Load parent ip (2cd parameter) */
>> + lea (%esp), %ecx
>> + pushl %ecx /* Save pt_regs as 4th parameter */
>> + leal function_trace_op, %ecx /* Save ftrace_pos in 3rd parameter */
>> +
>> +GLOBAL(ftrace_regs_call)
>> + call ftrace_stub
>> +
>> + addl $4, %esp /* Skip pt_regs */
>> + movl 14*4(%esp), %eax /* Move flags back into cs */
>> + movl %eax, 13*4(%esp) /* Needed to keep addl from modifying flags */
>> + movl 12*4(%esp), %eax /* Get return ip from regs->ip */
>> + addl $MCOUNT_INSN_SIZE, %eax
>> + movl %eax, 14*4(%esp) /* Put return ip back for ret */
>> +
>> + popl %ebx
>> + popl %ecx
>> + popl %edx
>> + popl %esi
>> + popl %edi
>> + popl %ebp
>> + popl %eax
>> + popl %ds
>> + popl %es
>> + popl %fs
>> + popl %gs
>> + addl $8, %esp /* Skip orig_ax and ip */
>> + popf /* Pop flags at end (no addl to corrupt flags) */
>> + jmp ftrace_ret
>> +
>> +ftrace_restore_flags:
>> + popf
>> + jmp ftrace_stub
>> #else /* ! CONFIG_DYNAMIC_FTRACE */
>>
>> ENTRY(mcount)
>> diff --git a/arch/x86/kernel/ftrace.c b/arch/x86/kernel/ftrace.c
>> index b90eb1a..1d41402 100644
>> --- a/arch/x86/kernel/ftrace.c
>> +++ b/arch/x86/kernel/ftrace.c
>> @@ -206,7 +206,6 @@ static int
>> ftrace_modify_code(unsigned long ip, unsigned const char *old_code,
>> unsigned const char *new_code);
>>
>> -#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
>> /*
>> * Should never be called:
>> * As it is only called by __ftrace_replace_code() which is called by
>> @@ -221,7 +220,6 @@ int ftrace_modify_call(struct dyn_ftrace *rec, unsigned long old_addr,
>> WARN_ON(1);
>> return -EINVAL;
>> }
>> -#endif
>>
>> int ftrace_update_ftrace_func(ftrace_func_t func)
>> {
>> @@ -237,7 +235,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>>
>> ret = ftrace_modify_code(ip, old, new);
>>
>> -#ifdef ARCH_SUPPORTS_FTRACE_SAVE_REGS
>> /* Also update the regs callback function */
>> if (!ret) {
>> ip = (unsigned long)(&ftrace_regs_call);
>> @@ -245,7 +242,6 @@ int ftrace_update_ftrace_func(ftrace_func_t func)
>> new = ftrace_call_replace(ip, (unsigned long)func);
>> ret = ftrace_modify_code(ip, old, new);
>> }
>> -#endif
>>
>> atomic_dec(&modifying_ftrace_code);
>>
>
>
> --
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--
Masami HIRAMATSU
Software Platform Research Dept. Linux Technology Center
Hitachi, Ltd., Yokohama Research Laboratory
E-mail: masami.hiramatsu.pt@hitachi.com




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