The following commit has been merged into the x86/asm branch of tip: Commit-ID: 0f42c1ad44d437f75b840b572376fd538fbb9643 Gitweb: https://git.kernel.org/tip/0f42c1ad44d437f75b840b572376fd538fbb9643 Author: Borislav Petkov <bp@xxxxxxx> AuthorDate: Mon, 21 Oct 2019 17:18:23 +02:00 Committer: Borislav Petkov <bp@xxxxxxx> CommitterDate: Fri, 25 Oct 2019 10:52:22 +02:00 x86/ftrace: Get rid of function_hook History lesson courtesy of Steve: "When ftrace first was introduced to the kernel, it used gcc's mcount profiling mechanism. The mcount mechanism would add a call to "mcount" at the start of every function but after the stack frame was set up. Later, in gcc 4.6, gcc introduced -mfentry, that would create a call to "__fentry__" instead of "mcount", before the stack frame was set up. In order to handle both cases, ftrace defined a macro "function_hook" that would be either "mcount" or "__fentry__" depending on which one was being used. The Linux kernel no longer supports the "mcount" method, thus there's no reason to keep the "function_hook" define around. Simply use "__fentry__", as there is no ambiguity to the name anymore." Drop it everywhere. Signed-off-by: Borislav Petkov <bp@xxxxxxx> Acked-by: Jiri Slaby <jslaby@xxxxxxx> Cc: "H. Peter Anvin" <hpa@xxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> 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 Link: http://lkml.kernel.org/r/20191018124800.0a7006bb@xxxxxxxxxxxxxxxxxx --- 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 29ccd6e..f55c2bb 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 8ed1f5d..e8a9f83 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_FUNC_START(__fentry__) ret -SYM_FUNC_END(function_hook) +SYM_FUNC_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 69c8d1b..6e8961c 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_FUNC_START(__fentry__) retq -SYM_FUNC_END(function_hook) +SYM_FUNC_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_FUNC_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_FUNC_END(__fentry__) +EXPORT_SYMBOL(__fentry__) #endif /* CONFIG_DYNAMIC_FTRACE */ #ifdef CONFIG_FUNCTION_GRAPH_TRACER
