From: Borislav Petkov <[email protected]> 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 <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Jiri Slaby <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Josh Poimboeuf <[email protected]> Cc: [email protected] Cc: [email protected] Cc: Peter Zijlstra <[email protected]> Cc: "Steven Rostedt (VMware)" <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: [email protected] --- 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 -- 2.21.0 -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette
