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Subject[tip:locking/core] x86/jump_label: Add a __jump_label_set_jump_code() helper
Commit-ID:  4cc6620b5e4c8953c725bcfab86a57df01e83a7c
Gitweb: https://git.kernel.org/tip/4cc6620b5e4c8953c725bcfab86a57df01e83a7c
Author: Daniel Bristot de Oliveira <bristot@redhat.com>
AuthorDate: Wed, 12 Jun 2019 11:57:27 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 17 Jun 2019 12:09:20 +0200

x86/jump_label: Add a __jump_label_set_jump_code() helper

Move the definition of the code to be written from
__jump_label_transform() to a specialized function. No functional
change.

Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Scott Wood <swood@redhat.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/d2f52a0010ecd399cf9b02a65bcf5836571b9e52.1560325897.git.bristot@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/jump_label.c | 52 +++++++++++++++++++++++---------------------
1 file changed, 27 insertions(+), 25 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index e631c358f7f4..f33408f1c3f6 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -35,41 +35,43 @@ static void bug_at(unsigned char *ip, int line)
BUG();
}

-static void __ref __jump_label_transform(struct jump_entry *entry,
- enum jump_label_type type,
- int init)
+static void __jump_label_set_jump_code(struct jump_entry *entry,
+ enum jump_label_type type,
+ union jump_code_union *code,
+ int init)
{
- union jump_code_union jmp;
const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
- const void *expect, *code;
+ const void *expect;
int line;

- jmp.jump = 0xe9;
- jmp.offset = jump_entry_target(entry) -
- (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
-
- if (type == JUMP_LABEL_JMP) {
- if (init) {
- expect = default_nop; line = __LINE__;
- } else {
- expect = ideal_nop; line = __LINE__;
- }
+ code->jump = 0xe9;
+ code->offset = jump_entry_target(entry) -
+ (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);

- code = &jmp.code;
+ if (init) {
+ expect = default_nop; line = __LINE__;
+ } else if (type == JUMP_LABEL_JMP) {
+ expect = ideal_nop; line = __LINE__;
} else {
- if (init) {
- expect = default_nop; line = __LINE__;
- } else {
- expect = &jmp.code; line = __LINE__;
- }
-
- code = ideal_nop;
+ expect = code->code; line = __LINE__;
}

if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
bug_at((void *)jump_entry_code(entry), line);

+ if (type == JUMP_LABEL_NOP)
+ memcpy(code, ideal_nop, JUMP_LABEL_NOP_SIZE);
+}
+
+static void __ref __jump_label_transform(struct jump_entry *entry,
+ enum jump_label_type type,
+ int init)
+{
+ union jump_code_union code;
+
+ __jump_label_set_jump_code(entry, type, &code, init);
+
/*
* As long as only a single processor is running and the code is still
* not marked as RO, text_poke_early() can be used; Checking that
@@ -82,12 +84,12 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
* always nop being the 'currently valid' instruction
*/
if (init || system_state == SYSTEM_BOOTING) {
- text_poke_early((void *)jump_entry_code(entry), code,
+ text_poke_early((void *)jump_entry_code(entry), &code,
JUMP_LABEL_NOP_SIZE);
return;
}

- text_poke_bp((void *)jump_entry_code(entry), code, JUMP_LABEL_NOP_SIZE,
+ text_poke_bp((void *)jump_entry_code(entry), &code, JUMP_LABEL_NOP_SIZE,
(void *)jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
}

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