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authorSteven Rostedt <srostedt@redhat.com>2012-02-01 09:59:24 -0500
committerSteven Rostedt <rostedt@goodmis.org>2013-08-06 21:54:33 -0400
commitfb40d7a8994a3cc7a1e1c1f3258ea8662a366916 (patch)
treea1d3664ba12dafc4029b6fc3aff2adf767a4fb83
parent9c85f3bdf400665eecf62658a9106501f6a77a13 (diff)
x86/jump-label: Show where and what was wrong on errors
When modifying text sections for jump labels, a paranoid check is performed. If the check fails, the system "bugs". But why it failed is not shown. The BUG_ON()s in the jump label update code is replaced with bug_at(ip). This is a function that will show what pointer failed, and what was at the location of the failure that made jump label panic. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--arch/x86/kernel/jump_label.c21
1 files changed, 18 insertions, 3 deletions
diff --git a/arch/x86/kernel/jump_label.c b/arch/x86/kernel/jump_label.c
index 24cf2b25ce73..912a52812916 100644
--- a/arch/x86/kernel/jump_label.c
+++ b/arch/x86/kernel/jump_label.c
@@ -24,6 +24,18 @@ union jump_code_union {
24 } __attribute__((packed)); 24 } __attribute__((packed));
25}; 25};
26 26
27static void bug_at(unsigned char *ip, int line)
28{
29 /*
30 * The location is not an op that we were expecting.
31 * Something went wrong. Crash the box, as something could be
32 * corrupting the kernel.
33 */
34 pr_warning("Unexpected op at %pS [%p] (%02x %02x %02x %02x %02x) %s:%d\n",
35 ip, ip, ip[0], ip[1], ip[2], ip[3], ip[4], __FILE__, line);
36 BUG();
37}
38
27static void __jump_label_transform(struct jump_entry *entry, 39static void __jump_label_transform(struct jump_entry *entry,
28 enum jump_label_type type, 40 enum jump_label_type type,
29 void *(*poker)(void *, const void *, size_t), 41 void *(*poker)(void *, const void *, size_t),
@@ -37,7 +49,8 @@ static void __jump_label_transform(struct jump_entry *entry,
37 * We are enabling this jump label. If it is not a nop 49 * We are enabling this jump label. If it is not a nop
38 * then something must have gone wrong. 50 * then something must have gone wrong.
39 */ 51 */
40 BUG_ON(memcmp((void *)entry->code, ideal_nop, 5) != 0); 52 if (unlikely(memcmp((void *)entry->code, ideal_nop, 5) != 0))
53 bug_at((void *)entry->code, __LINE__);
41 54
42 code.jump = 0xe9; 55 code.jump = 0xe9;
43 code.offset = entry->target - 56 code.offset = entry->target -
@@ -51,12 +64,14 @@ static void __jump_label_transform(struct jump_entry *entry,
51 */ 64 */
52 if (init) { 65 if (init) {
53 const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP }; 66 const unsigned char default_nop[] = { STATIC_KEY_INIT_NOP };
54 BUG_ON(memcmp((void *)entry->code, default_nop, 5) != 0); 67 if (unlikely(memcmp((void *)entry->code, default_nop, 5) != 0))
68 bug_at((void *)entry->code, __LINE__);
55 } else { 69 } else {
56 code.jump = 0xe9; 70 code.jump = 0xe9;
57 code.offset = entry->target - 71 code.offset = entry->target -
58 (entry->code + JUMP_LABEL_NOP_SIZE); 72 (entry->code + JUMP_LABEL_NOP_SIZE);
59 BUG_ON(memcmp((void *)entry->code, &code, 5) != 0); 73 if (unlikely(memcmp((void *)entry->code, &code, 5) != 0))
74 bug_at((void *)entry->code, __LINE__);
60 } 75 }
61 memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE); 76 memcpy(&code, ideal_nops[NOP_ATOMIC5], JUMP_LABEL_NOP_SIZE);
62 } 77 }