On 21. 10. 19, 16:10, Borislav Petkov wrote: > From: Borislav Petkov <bp@xxxxxxx> > > function_hook is used as a better name than the default __fentry__ > which is the profiling counter which gcc adds before every function's > prologue. Thus, it is not called from C and cannot have the same > semantics as a pure C function - it saves/restores regs so that a C > function can be called. > > Drop the function_hook symbol and use __fentry__ directly for better > alignment with gcc's documentation. > > Switch the marking to SYM_CODE_START/_END which is reserved for > non-standard, special functions. > > Signed-off-by: Borislav Petkov <bp@xxxxxxx> > Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> > Cc: Ingo Molnar <mingo@xxxxxxxxxx> > Cc: Jiri Slaby <jslaby@xxxxxxx> On the top of Steven's comment: Acked-by: Jiri Slaby <jslaby@xxxxxxx> Thanks for taking care of this while my tooth was causing me pain. > Cc: Jonathan Corbet <corbet@xxxxxxx> > Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx> > Cc: linux-doc@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> > Cc: "Steven Rostedt (VMware)" <rostedt@xxxxxxxxxxx> > Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> > Cc: x86@xxxxxxxxxx > --- > Documentation/asm-annotations.rst | 4 ++-- > arch/x86/kernel/ftrace_32.S | 8 +++----- > arch/x86/kernel/ftrace_64.S | 13 ++++++------- > 3 files changed, 11 insertions(+), 14 deletions(-) > > diff --git a/Documentation/asm-annotations.rst b/Documentation/asm-annotations.rst > index 29ccd6e61fe5..f55c2bb74d00 100644 > --- a/Documentation/asm-annotations.rst > +++ b/Documentation/asm-annotations.rst > @@ -117,9 +117,9 @@ This section covers ``SYM_FUNC_*`` and ``SYM_CODE_*`` enumerated above. > So in most cases, developers should write something like in the following > example, having some asm instructions in between the macros, of course:: > > - SYM_FUNC_START(function_hook) > + SYM_FUNC_START(memset) > ... asm insns ... > - SYM_FUNC_END(function_hook) > + SYM_FUNC_END(memset) > > In fact, this kind of annotation corresponds to the now deprecated ``ENTRY`` > and ``ENDPROC`` macros. > diff --git a/arch/x86/kernel/ftrace_32.S b/arch/x86/kernel/ftrace_32.S > index 8ed1f5d371f0..77be7e7e5e59 100644 > --- a/arch/x86/kernel/ftrace_32.S > +++ b/arch/x86/kernel/ftrace_32.S > @@ -12,18 +12,16 @@ > #include <asm/frame.h> > #include <asm/asm-offsets.h> > > -# define function_hook __fentry__ > -EXPORT_SYMBOL(__fentry__) > - > #ifdef CONFIG_FRAME_POINTER > # define MCOUNT_FRAME 1 /* using frame = true */ > #else > # define MCOUNT_FRAME 0 /* using frame = false */ > #endif > > -SYM_FUNC_START(function_hook) > +SYM_CODE_START(__fentry__) > ret > -SYM_FUNC_END(function_hook) > +SYM_CODE_END(__fentry__) > +EXPORT_SYMBOL(__fentry__) > > SYM_CODE_START(ftrace_caller) > > diff --git a/arch/x86/kernel/ftrace_64.S b/arch/x86/kernel/ftrace_64.S > index 69c8d1b9119e..3029fe4f8547 100644 > --- a/arch/x86/kernel/ftrace_64.S > +++ b/arch/x86/kernel/ftrace_64.S > @@ -14,9 +14,6 @@ > .code64 > .section .entry.text, "ax" > > -# define function_hook __fentry__ > -EXPORT_SYMBOL(__fentry__) > - > #ifdef CONFIG_FRAME_POINTER > /* Save parent and function stack frames (rip and rbp) */ > # define MCOUNT_FRAME_SIZE (8+16*2) > @@ -132,9 +129,10 @@ EXPORT_SYMBOL(__fentry__) > > #ifdef CONFIG_DYNAMIC_FTRACE > > -SYM_FUNC_START(function_hook) > +SYM_CODE_START(__fentry__) > retq > -SYM_FUNC_END(function_hook) > +SYM_CODE_END(__fentry__) > +EXPORT_SYMBOL(__fentry__) > > SYM_FUNC_START(ftrace_caller) > /* save_mcount_regs fills in first two parameters */ > @@ -248,7 +246,7 @@ SYM_FUNC_END(ftrace_regs_caller) > > #else /* ! CONFIG_DYNAMIC_FTRACE */ > > -SYM_FUNC_START(function_hook) > +SYM_CODE_START(__fentry__) > cmpq $ftrace_stub, ftrace_trace_function > jnz trace > > @@ -279,7 +277,8 @@ trace: > restore_mcount_regs > > jmp fgraph_trace > -SYM_FUNC_END(function_hook) > +SYM_CODE_END(__fentry__) > +EXPORT_SYMBOL(__fentry__) > #endif /* CONFIG_DYNAMIC_FTRACE */ > > #ifdef CONFIG_FUNCTION_GRAPH_TRACER > -- js suse labs
