[PATCH V6 2/6] x86/jump_label: Add a __jump_label_set_jump_code() helper

Daniel Bristot de Oliveira
2019-06-12T09:57:49Z

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>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Chris von Recklinghausen <crecklin@redhat.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Scott Wood <swood@redhat.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Clark Williams <williams@redhat.com>
Cc: x86@kernel.org
Cc: linux-kernel@vger.kernel.org
---
arch/x86/kernel/jump_label.c | 41 +++++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 15 deletions(-)

diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index e631c358f7f4..d3328062b8cf 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -35,19 +35,19 @@ 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);
+ code->jump = 0xe9;
+ code->offset = jump_entry_target(entry) -
+ (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);

if (type == JUMP_LABEL_JMP) {
if (init) {
@@ -56,19 +56,30 @@ static void __ref __jump_label_transform(struct jump_entry *entry,
expect = ideal_nop; line = __LINE__;
}

- code = &jmp.code;
+ if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
+ bug_at((void *)jump_entry_code(entry), line);
+
} else {
if (init) {
expect = default_nop; line = __LINE__;
} else {
- expect = &jmp.code; line = __LINE__;
+ expect = code->code; line = __LINE__;
}

- code = ideal_nop;
+ if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
+ bug_at((void *)jump_entry_code(entry), line);
+
+ 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;

- if (memcmp((void *)jump_entry_code(entry), expect, JUMP_LABEL_NOP_SIZE))
- bug_at((void *)jump_entry_code(entry), line);
+ __jump_label_set_jump_code(entry, type, &code, init);

/*
* As long as only a single processor is running and the code is still
@@ -82,12 +93,12 @@ 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);
}

--
2.20.1