Re: [PATCH 1/1] fentry: x86, cleanup function_hook uses

From: Steven Rostedt
Date: Tue Oct 20 2015 - 15:02:36 EST


On Tue, 6 Oct 2015 14:40:21 +0200
Jiri Slaby <jslaby@xxxxxxx> wrote:

> Let's define fentry_hook depending on CC_USING_FENTRY and use that
> macro all over. This saves some #ifdef's here and there.
>
> We do not use the old macro function_hook since it is too generic.
> Hence we introduce fentry_hook which corresponds to what it is.

Actually, I think I like function_hook better that fentry_hook, because
mcount is not an fentry.

What else do you think could be used as "function_hook"?

-- Steve


>
> Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
> Cc: <x86@xxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> ---
> arch/x86/include/asm/fentry.h | 14 ++++++++++++++
> arch/x86/include/asm/ftrace.h | 11 ++++-------
> arch/x86/kernel/mcount_64.S | 15 +++++----------
> arch/x86/kernel/x8664_ksyms_64.c | 8 ++------
> 4 files changed, 25 insertions(+), 23 deletions(-)
> create mode 100644 arch/x86/include/asm/fentry.h
>
> diff --git a/arch/x86/include/asm/fentry.h b/arch/x86/include/asm/fentry.h
> new file mode 100644
> index 000000000000..febe8d272f0f
> --- /dev/null
> +++ b/arch/x86/include/asm/fentry.h
> @@ -0,0 +1,14 @@
> +#ifndef ASM_FENTRY_H
> +#define ASM_FENTRY_H
> +
> +#ifdef CC_USING_FENTRY
> +# define fentry_hook __fentry__
> +#else
> +# define fentry_hook mcount
> +#endif
> +
> +#ifndef __ASSEMBLY__
> +extern void fentry_hook(void);
> +#endif /* __ASSEMBLY__ */
> +
> +#endif /* ASM_FENTRY_H */
> diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h
> index 24938852db30..dc235b3659da 100644
> --- a/arch/x86/include/asm/ftrace.h
> +++ b/arch/x86/include/asm/ftrace.h
> @@ -2,11 +2,10 @@
> #define _ASM_X86_FTRACE_H
>
> #ifdef CONFIG_FUNCTION_TRACER
> -#ifdef CC_USING_FENTRY
> -# define MCOUNT_ADDR ((unsigned long)(__fentry__))
> -#else
> -# define MCOUNT_ADDR ((unsigned long)(mcount))
> -#endif
> +
> +#include <asm/fentry.h>
> +
> +#define MCOUNT_ADDR ((unsigned long)(fentry_hook))
> #define MCOUNT_INSN_SIZE 5 /* sizeof mcount call */
>
> #ifdef CONFIG_DYNAMIC_FTRACE
> @@ -14,9 +13,7 @@
> #endif
>
> #ifndef __ASSEMBLY__
> -extern void mcount(void);
> extern atomic_t modifying_ftrace_code;
> -extern void __fentry__(void);
>
> static inline unsigned long ftrace_call_adjust(unsigned long addr)
> {
> diff --git a/arch/x86/kernel/mcount_64.S b/arch/x86/kernel/mcount_64.S
> index 94ea120fa21f..ac8d5296d6ec 100644
> --- a/arch/x86/kernel/mcount_64.S
> +++ b/arch/x86/kernel/mcount_64.S
> @@ -6,6 +6,7 @@
>
> #include <linux/linkage.h>
> #include <asm/ptrace.h>
> +#include <asm/fentry.h>
> #include <asm/ftrace.h>
>
>
> @@ -15,12 +16,6 @@
>
> #ifdef CONFIG_FUNCTION_TRACER
>
> -#ifdef CC_USING_FENTRY
> -# define function_hook __fentry__
> -#else
> -# define function_hook mcount
> -#endif
> -
> /* All cases save the original rbp (8 bytes) */
> #ifdef CONFIG_FRAME_POINTER
> # ifdef CC_USING_FENTRY
> @@ -147,9 +142,9 @@
>
> #ifdef CONFIG_DYNAMIC_FTRACE
>
> -ENTRY(function_hook)
> +ENTRY(fentry_hook)
> retq
> -END(function_hook)
> +END(fentry_hook)
>
> ENTRY(ftrace_caller)
> /* save_mcount_regs fills in first two parameters */
> @@ -258,7 +253,7 @@ END(ftrace_regs_caller)
>
> #else /* ! CONFIG_DYNAMIC_FTRACE */
>
> -ENTRY(function_hook)
> +ENTRY(fentry_hook)
> cmpq $ftrace_stub, ftrace_trace_function
> jnz trace
>
> @@ -283,7 +278,7 @@ trace:
> restore_mcount_regs
>
> jmp fgraph_trace
> -END(function_hook)
> +END(fentry_hook)
> #endif /* CONFIG_DYNAMIC_FTRACE */
> #endif /* CONFIG_FUNCTION_TRACER */
>
> diff --git a/arch/x86/kernel/x8664_ksyms_64.c b/arch/x86/kernel/x8664_ksyms_64.c
> index a0695be19864..5607abc110c7 100644
> --- a/arch/x86/kernel/x8664_ksyms_64.c
> +++ b/arch/x86/kernel/x8664_ksyms_64.c
> @@ -10,15 +10,11 @@
> #include <asm/pgtable.h>
> #include <asm/uaccess.h>
> #include <asm/desc.h>
> -#include <asm/ftrace.h>
> +#include <asm/fentry.h>
>
> #ifdef CONFIG_FUNCTION_TRACER
> /* mcount and __fentry__ are defined in assembly */
> -#ifdef CC_USING_FENTRY
> -EXPORT_SYMBOL(__fentry__);
> -#else
> -EXPORT_SYMBOL(mcount);
> -#endif
> +EXPORT_SYMBOL(fentry_hook);
> #endif
>
> EXPORT_SYMBOL(__get_user_1);

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/