* Peter Zijlstra <pet...@infradead.org> wrote:
> --- a/arch/x86/kernel/jump_label.c
> +++ b/arch/x86/kernel/jump_label.c
> @@ -35,18 +35,19 @@ static void bug_at(unsigned char *ip, in
> BUG();
> }
>
> -static void __jump_label_set_jump_code(struct jump_entry *entry,
> - enum jump_label_type type,
> - union jump_code_union *code,
> - int init)
> +static const void *
> +__jump_label_set_jump_code(struct jump_entry *entry, enum jump_label_type
> type, int init)
> {
> + static union jump_code_union code; /* relies on text_mutex */
> const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
> const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
> const void *expect;
> int line;
>
> - code->jump = 0xe9;
> - code->offset = jump_entry_target(entry) -
> + lockdep_assert_held(&text_mutex);
> +
> + code.jump = JMP32_INSN_OPCODE;
> + code.offset = jump_entry_target(entry) -
> (jump_entry_code(entry) + JUMP_LABEL_NOP_SIZE);
>
> if (init) {
> @@ -54,23 +55,23 @@ static void __jump_label_set_jump_code(s
> } else if (type == JUMP_LABEL_JMP) {
> expect = ideal_nop; line = __LINE__;
> } else {
> - expect = code->code; line = __LINE__;
> + expect = code.code; line = __LINE__;
Side note: the whole 'line' logic looked weird to me and it obsfuscates
the logic a bit, and I had to look it up to see what it's about:
improving the debug output of text-patching crashes.
How about something like the below on top of your queue? We have %phD
that can nicely print instructions in hex.
Totally untested though.
Thanks,
Ingo
---
arch/x86/kernel/jump_label.c | 21 ++++++++++-----------
1 file changed, 10 insertions(+), 11 deletions(-)
Index: tip/arch/x86/kernel/jump_label.c
===================================================================
--- tip.orig/arch/x86/kernel/jump_label.c
+++ tip/arch/x86/kernel/jump_label.c
@@ -16,14 +16,15 @@
#include <asm/alternative.h>
#include <asm/text-patching.h>
-static void bug_at(const void *ip, int line)
+static void bug_at(const void *ip, const void *op_expected, const void
*op_unexpected)
{
/*
* The location is not an op that we were expecting.
* Something went wrong. Crash the box, as something could be
* corrupting the kernel.
*/
- pr_crit("jump_label: Fatal kernel bug, unexpected op at %pS [%p] (%5ph)
%d\n", ip, ip, ip, line);
+ pr_crit("jump_label: Fatal kernel bug, expected op (%*phD), unexpected
op (%*phD) at %pS [%p] (%5ph\n",
+ JUMP_LABEL_NOP_SIZE, op_expected, JUMP_LABEL_NOP_SIZE,
op_unexpected, ip, ip, ip);
BUG();
}
@@ -34,23 +35,21 @@ __jump_label_set_jump_code(struct jump_e
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
const void *expect, *code;
const void *addr, *dest;
- int line;
addr = (void *)jump_entry_code(entry);
dest = (void *)jump_entry_target(entry);
code = text_gen_insn(JMP32_INSN_OPCODE, addr, dest);
- if (init) {
- expect = default_nop; line = __LINE__;
- } else if (type == JUMP_LABEL_JMP) {
- expect = ideal_nop; line = __LINE__;
- } else {
- expect = code; line = __LINE__;
- }
+ if (init)
+ expect = default_nop;
+ else if (type == JUMP_LABEL_JMP)
+ expect = ideal_nop;
+ else
+ expect = code;
if (memcmp(addr, expect, JUMP_LABEL_NOP_SIZE))
- bug_at(addr, line);
+ bug_at(addr, expect, addr);
if (type == JUMP_LABEL_NOP)
code = ideal_nop;
