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Subject[tip:perf/core] kprobes/x86: Fix the description of __copy_instruction()
Commit-ID:  129d17e8e8daf50f8aff4941fb4a9cda027ab9cf
Gitweb: http://git.kernel.org/tip/129d17e8e8daf50f8aff4941fb4a9cda027ab9cf
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Wed, 29 Mar 2017 13:58:06 +0900
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 12 Apr 2017 09:23:45 +0200

kprobes/x86: Fix the description of __copy_instruction()

Fix the description comment of __copy_instruction() function
since it has already been changed to return the length of the
copied instruction.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/149076347582.22469.3775133607244923462.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/kprobes/core.c | 10 +++++-----
1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 9eae5a6..81d4dc7 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -350,11 +350,10 @@ static int is_IF_modifier(kprobe_opcode_t *insn)
}

/*
- * Copy an instruction and adjust the displacement if the instruction
- * uses the %rip-relative addressing mode.
- * If it does, Return the address of the 32-bit displacement word.
- * If not, return null.
- * Only applicable to 64-bit x86.
+ * Copy an instruction with recovering modified instruction by kprobes
+ * and adjust the displacement if the instruction uses the %rip-relative
+ * addressing mode.
+ * This returns the length of copied instruction, or 0 if it has an error.
*/
int __copy_instruction(u8 *dest, u8 *src)
{
@@ -376,6 +375,7 @@ int __copy_instruction(u8 *dest, u8 *src)
memcpy(dest, insn.kaddr, length);

#ifdef CONFIG_X86_64
+ /* Only x86_64 has RIP relative instructions */
if (insn_rip_relative(&insn)) {
s64 newdisp;
u8 *disp;
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