Merge tag 'core-headers-2020-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip (5ece0817) · Commits · 戴 / test

arch/x86/include/asm/bug.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -3,6 +3,7 @@
		#define _ASM_X86_BUG_H

		#include <linux/stringify.h>
		#include <linux/instrumentation.h>

		/*
		* Despite that some emulators terminate on UD2, we use it for WARN().

include/asm-generic/bug.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -3,6 +3,7 @@
		#define _ASM_GENERIC_BUG_H

		#include <linux/compiler.h>
		#include <linux/instrumentation.h>

		#define CUT_HERE "------------[ cut here ]------------\n"

include/linux/compiler.h

+0 −53

Original line number	Diff line number	Diff line
		@@ -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

include/linux/context_tracking.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -5,6 +5,8 @@
		#include <linux/sched.h>
		#include <linux/vtime.h>
		#include <linux/context_tracking_state.h>
		#include <linux/instrumentation.h>

		#include <asm/ptrace.h>

include/linux/instrumentation.h

0 → 100644

+57 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0 */
		#ifndef __LINUX_INSTRUMENTATION_H
		#define __LINUX_INSTRUMENTATION_H

		#if defined(CONFIG_DEBUG_ENTRY) && defined(CONFIG_STACK_VALIDATION)

		/* 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__)); \
		})
		#else
		# define instrumentation_begin() do { } while(0)
		# define instrumentation_end() do { } while(0)
		#endif

		#endif /* __LINUX_INSTRUMENTATION_H */

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