[RFC][PATCH 5/8] jump_label, x86: Improve error when we fail expected text

From: Peter Zijlstra
Date: Fri Jun 28 2019 - 09:36:36 EST


There is only a single usage site left, remove the function and extend
the print to include more information, like the expected text and the
patch type.

Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/kernel/jump_label.c | 24 +++++++++++-------------
1 file changed, 11 insertions(+), 13 deletions(-)

--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -24,17 +24,6 @@ union jump_code_union {
} __attribute__((packed));
};

-static void bug_at(unsigned char *ip, int line)
-{
- /*
- * 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);
- BUG();
-}
-
static void __jump_label_set_jump_code(struct jump_entry *entry,
enum jump_label_type type,
union jump_code_union *code,
@@ -42,6 +31,7 @@ static void __jump_label_set_jump_code(s
{
const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
const unsigned char *ideal_nop = ideal_nops[NOP_ATOMIC5];
+ unsigned char *ip = (void *)jump_entry_code(entry);
const void *expect;
int line;

@@ -57,8 +47,16 @@ static void __jump_label_set_jump_code(s
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 (memcmp(ip, expect, JUMP_LABEL_NOP_SIZE)) {
+ /*
+ * 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 != %5ph)) line:%d init:%d type:%d\n",
+ ip, ip, ip, expect, line, init, type);
+ BUG();
+ }

if (type == JUMP_LABEL_NOP)
memcpy(code, ideal_nop, JUMP_LABEL_NOP_SIZE);