diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:25:40 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-03 14:25:40 -0700 |
commit | 5ece08178d6567db5ef0090b1ae7f795c3c36161 (patch) | |
tree | e052c9473b8ec03b278d74e829da21a3c33a41a6 /include/linux/compiler.h | |
parent | c8e69391d046a6acaa6a4cf72f9952ecd77d3085 (diff) | |
parent | d19e789f068b3d633cbac430764962f404198022 (diff) |
Merge tag 'core-headers-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull header cleanup from Ingo Molnar:
"Separate out the instrumentation_begin()/end() bits from compiler.h"
* tag 'core-headers-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
compiler.h: Move instrumentation_begin()/end() to new <linux/instrumentation.h> header
Diffstat (limited to 'include/linux/compiler.h')
-rw-r--r-- | include/linux/compiler.h | 53 |
1 files changed, 0 insertions, 53 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 59f7194fdf08..6810d80acb0b 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -120,65 +120,12 @@ void ftrace_likely_update(struct ftrace_likely_data *f, int val, /* Annotate a C jump table to allow objtool to follow the code flow */ #define __annotate_jump_table __section(.rodata..c_jump_table) -#ifdef CONFIG_DEBUG_ENTRY -/* Begin/end of an instrumentation safe region */ -#define instrumentation_begin() ({ \ - asm volatile("%c0: nop\n\t" \ - ".pushsection .discard.instr_begin\n\t" \ - ".long %c0b - .\n\t" \ - ".popsection\n\t" : : "i" (__COUNTER__)); \ -}) - -/* - * Because instrumentation_{begin,end}() can nest, objtool validation considers - * _begin() a +1 and _end() a -1 and computes a sum over the instructions. - * When the value is greater than 0, we consider instrumentation allowed. - * - * There is a problem with code like: - * - * noinstr void foo() - * { - * instrumentation_begin(); - * ... - * if (cond) { - * instrumentation_begin(); - * ... - * instrumentation_end(); - * } - * bar(); - * instrumentation_end(); - * } - * - * If instrumentation_end() would be an empty label, like all the other - * annotations, the inner _end(), which is at the end of a conditional block, - * would land on the instruction after the block. - * - * If we then consider the sum of the !cond path, we'll see that the call to - * bar() is with a 0-value, even though, we meant it to happen with a positive - * value. - * - * To avoid this, have _end() be a NOP instruction, this ensures it will be - * part of the condition block and does not escape. - */ -#define instrumentation_end() ({ \ - asm volatile("%c0: nop\n\t" \ - ".pushsection .discard.instr_end\n\t" \ - ".long %c0b - .\n\t" \ - ".popsection\n\t" : : "i" (__COUNTER__)); \ -}) -#endif /* CONFIG_DEBUG_ENTRY */ - #else #define annotate_reachable() #define annotate_unreachable() #define __annotate_jump_table #endif -#ifndef instrumentation_begin -#define instrumentation_begin() do { } while(0) -#define instrumentation_end() do { } while(0) -#endif - #ifndef ASM_UNREACHABLE # define ASM_UNREACHABLE #endif |