[RFC PATCH 2/4] x86, alternatives: Cleanup DPRINTK macro

Borislav Petkov
2015-01-05T15:00:24Z

Make it pass __func__ implicitly. Also, dump info about each replacing
we're doing. Fixup comments and style while at it.

Signed-off-by: Borislav Petkov <bp@suse.de>
---
arch/x86/kernel/alternative.c | 41 +++++++++++++++++++++++++----------------
1 file changed, 25 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 703130f469ec..1e86e85bcf58 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -52,10 +52,10 @@ static int __init setup_noreplace_paravirt(char *str)
__setup("noreplace-paravirt", setup_noreplace_paravirt);
#endif

-#define DPRINTK(fmt, ...) \
-do { \
- if (debug_alternative) \
- printk(KERN_DEBUG fmt, ##__VA_ARGS__); \
+#define DPRINTK(fmt, args...) \
+do { \
+ if (debug_alternative) \
+ printk(KERN_DEBUG "%s: " fmt "\n", __func__, ##args); \
} while (0)

/*
@@ -243,12 +243,13 @@ extern struct alt_instr __alt_instructions[], __alt_instructions_end[];
extern s32 __smp_locks[], __smp_locks_end[];
void *text_poke_early(void *addr, const void *opcode, size_t len);

-/* Replace instructions with better alternatives for this CPU type.
- This runs before SMP is initialized to avoid SMP problems with
- self modifying code. This implies that asymmetric systems where
- APs have less capabilities than the boot processor are not handled.
- Tough. Make sure you disable such features by hand. */
-
+/*
+ * Replace instructions with better alternatives for this CPU type. This runs
+ * before SMP is initialized to avoid SMP problems with self modifying code.
+ * This implies that asymmetric systems where APs have less capabilities than
+ * the boot processor are not handled. Tough. Make sure you disable such
+ * features by hand.
+ */
void __init_or_module apply_alternatives(struct alt_instr *start,
struct alt_instr *end)
{
@@ -256,10 +257,10 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
u8 *instr, *replacement;
u8 insnbuf[MAX_PATCH_LEN];

- DPRINTK("%s: alt table %p -> %p\n", __func__, start, end);
+ DPRINTK("alt table %p -> %p", start, end);
/*
* The scan order should be from start to end. A later scanned
- * alternative code can overwrite a previous scanned alternative code.
+ * alternative code can overwrite previously scanned alternative code.
* Some kernel functions (e.g. memcpy, memset, etc) use this order to
* patch code.
*
@@ -275,11 +276,19 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
if (!boot_cpu_has(a->cpuid))
continue;

+ DPRINTK("feat: %d*32+%d, old: (%p, len: %d), repl: (%p, len: %d)",
+ a->cpuid >> 5,
+ a->cpuid & 0x1f,
+ instr, a->instrlen,
+ replacement, a->replacementlen);
+
memcpy(insnbuf, replacement, a->replacementlen);

/* 0xe8 is a relative jump; fix the offset. */
- if (*insnbuf == 0xe8 && a->replacementlen == 5)
- *(s32 *)(insnbuf + 1) += replacement - instr;
+ if (*insnbuf == 0xe8 && a->replacementlen == 5) {
+ *(s32 *)(insnbuf + 1) += replacement - instr;
+ DPRINTK("Fix CALL offset: 0x%x", *(s32 *)(insnbuf + 1));
+ }

add_nops(insnbuf + a->replacementlen,
a->instrlen - a->replacementlen);
@@ -371,8 +380,8 @@ void __init_or_module alternatives_smp_module_add(struct module *mod,
smp->locks_end = locks_end;
smp->text = text;
smp->text_end = text_end;
- DPRINTK("%s: locks %p -> %p, text %p -> %p, name %s\n",
- __func__, smp->locks, smp->locks_end,
+ DPRINTK("locks %p -> %p, text %p -> %p, name %s\n",
+ smp->locks, smp->locks_end,
smp->text, smp->text_end, smp->name);

list_add_tail(&smp->next, &smp_alt_modules);
--
2.2.0.33.gc18b867