[PATCH v3 1/4] x86/alternative: Make debug-alternative selective
From: Peter Zijlstra
Date: Wed Feb 08 2023 - 12:18:25 EST
Using debug-alternative generates a *LOT* of output, extend it a bit
to select which of the many rewrites it reports on.
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
---
arch/x86/kernel/alternative.c | 62 +++++++++++++++++++++++++-----------------
1 file changed, 37 insertions(+), 25 deletions(-)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -37,11 +37,23 @@ EXPORT_SYMBOL_GPL(alternatives_patched);
#define MAX_PATCH_LEN (255-1)
-static int __initdata_or_module debug_alternative;
+#define DA_ALL (~0)
+#define DA_ALT 0x01
+#define DA_RET 0x02
+#define DA_RETPOLINE 0x04
+#define DA_ENDBR 0x08
+#define DA_SMP 0x10
+
+static unsigned int __initdata_or_module debug_alternative;
static int __init debug_alt(char *str)
{
- debug_alternative = 1;
+ if (str && *str == '=')
+ str++;
+
+ if (!str || kstrtouint(str, 0, &debug_alternative))
+ debug_alternative = DA_ALL;
+
return 1;
}
__setup("debug-alternative", debug_alt);
@@ -55,15 +67,15 @@ static int __init setup_noreplace_smp(ch
}
__setup("noreplace-smp", setup_noreplace_smp);
-#define DPRINTK(fmt, args...) \
+#define DPRINTK(type, fmt, args...) \
do { \
- if (debug_alternative) \
+ if (debug_alternative & DA_##type) \
printk(KERN_DEBUG pr_fmt(fmt) "\n", ##args); \
} while (0)
-#define DUMP_BYTES(buf, len, fmt, args...) \
+#define DUMP_BYTES(type, buf, len, fmt, args...) \
do { \
- if (unlikely(debug_alternative)) { \
+ if (unlikely(debug_alternative & DA_##type)) { \
int j; \
\
if (!(len)) \
@@ -148,7 +160,7 @@ recompute_jump(struct alt_instr *a, u8 *
tgt_rip = next_rip + o_dspl;
n_dspl = tgt_rip - orig_insn;
- DPRINTK("target RIP: %px, new_displ: 0x%x", tgt_rip, n_dspl);
+ DPRINTK(ALT, "target RIP: %px, new_displ: 0x%x", tgt_rip, n_dspl);
if (tgt_rip - orig_insn >= 0) {
if (n_dspl - 2 <= 127)
@@ -183,7 +195,7 @@ recompute_jump(struct alt_instr *a, u8 *
done:
- DPRINTK("final displ: 0x%08x, JMP 0x%lx",
+ DPRINTK(ALT, "final displ: 0x%08x, JMP 0x%lx",
n_dspl, (unsigned long)orig_insn + n_dspl + repl_len);
}
@@ -217,7 +229,7 @@ static __always_inline int optimize_nops
add_nops(instr + off, nnops);
local_irq_restore(flags);
- DUMP_BYTES(instr, instrlen, "%px: [%d:%d) optimized NOPs: ", instr, off, i);
+ DUMP_BYTES(ALT, instr, instrlen, "%px: [%d:%d) optimized NOPs: ", instr, off, i);
return nnops;
}
@@ -270,7 +282,7 @@ void __init_or_module noinline apply_alt
u8 *instr, *replacement;
u8 insn_buff[MAX_PATCH_LEN];
- DPRINTK("alt table %px, -> %px", start, end);
+ DPRINTK(ALT, "alt table %px, -> %px", start, end);
/*
* The scan order should be from start to end. A later scanned
* alternative code can overwrite previously scanned alternative code.
@@ -299,15 +311,15 @@ void __init_or_module noinline apply_alt
if (!boot_cpu_has(feature) == !(a->cpuid & ALTINSTR_FLAG_INV))
goto next;
- DPRINTK("feat: %s%d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d)",
+ DPRINTK(ALT, "feat: %s%d*32+%d, old: (%pS (%px) len: %d), repl: (%px, len: %d)",
(a->cpuid & ALTINSTR_FLAG_INV) ? "!" : "",
feature >> 5,
feature & 0x1f,
instr, instr, a->instrlen,
replacement, a->replacementlen);
- DUMP_BYTES(instr, a->instrlen, "%px: old_insn: ", instr);
- DUMP_BYTES(replacement, a->replacementlen, "%px: rpl_insn: ", replacement);
+ DUMP_BYTES(ALT, instr, a->instrlen, "%px: old_insn: ", instr);
+ DUMP_BYTES(ALT, replacement, a->replacementlen, "%px: rpl_insn: ", replacement);
memcpy(insn_buff, replacement, a->replacementlen);
insn_buff_sz = a->replacementlen;
@@ -320,7 +332,7 @@ void __init_or_module noinline apply_alt
*/
if (a->replacementlen == 5 && *insn_buff == 0xe8) {
*(s32 *)(insn_buff + 1) += replacement - instr;
- DPRINTK("Fix CALL offset: 0x%x, CALL 0x%lx",
+ DPRINTK(ALT, "Fix CALL offset: 0x%x, CALL 0x%lx",
*(s32 *)(insn_buff + 1),
(unsigned long)instr + *(s32 *)(insn_buff + 1) + 5);
}
@@ -331,7 +343,7 @@ void __init_or_module noinline apply_alt
for (; insn_buff_sz < a->instrlen; insn_buff_sz++)
insn_buff[insn_buff_sz] = 0x90;
- DUMP_BYTES(insn_buff, insn_buff_sz, "%px: final_insn: ", instr);
+ DUMP_BYTES(ALT, insn_buff, insn_buff_sz, "%px: final_insn: ", instr);
text_poke_early(instr, insn_buff, insn_buff_sz);
@@ -557,15 +569,15 @@ void __init_or_module noinline apply_ret
continue;
}
- DPRINTK("retpoline at: %pS (%px) len: %d to: %pS",
+ DPRINTK(RETPOLINE, "retpoline at: %pS (%px) len: %d to: %pS",
addr, addr, insn.length,
addr + insn.length + insn.immediate.value);
len = patch_retpoline(addr, &insn, bytes);
if (len == insn.length) {
optimize_nops(bytes, len);
- DUMP_BYTES(((u8*)addr), len, "%px: orig: ", addr);
- DUMP_BYTES(((u8*)bytes), len, "%px: repl: ", addr);
+ DUMP_BYTES(RETPOLINE, ((u8*)addr), len, "%px: orig: ", addr);
+ DUMP_BYTES(RETPOLINE, ((u8*)bytes), len, "%px: repl: ", addr);
text_poke_early(addr, bytes, len);
}
}
@@ -632,14 +644,14 @@ void __init_or_module noinline apply_ret
addr, dest, 5, addr))
continue;
- DPRINTK("return thunk at: %pS (%px) len: %d to: %pS",
+ DPRINTK(RET, "return thunk at: %pS (%px) len: %d to: %pS",
addr, addr, insn.length,
addr + insn.length + insn.immediate.value);
len = patch_return(addr, &insn, bytes);
if (len == insn.length) {
- DUMP_BYTES(((u8*)addr), len, "%px: orig: ", addr);
- DUMP_BYTES(((u8*)bytes), len, "%px: repl: ", addr);
+ DUMP_BYTES(RET, ((u8*)addr), len, "%px: orig: ", addr);
+ DUMP_BYTES(RET, ((u8*)bytes), len, "%px: repl: ", addr);
text_poke_early(addr, bytes, len);
}
}
@@ -669,13 +681,13 @@ static void poison_endbr(void *addr, boo
return;
}
- DPRINTK("ENDBR at: %pS (%px)", addr, addr);
+ DPRINTK(ENDBR, "ENDBR at: %pS (%px)", addr, addr);
/*
* When we have IBT, the lack of ENDBR will trigger #CP
*/
- DUMP_BYTES(((u8*)addr), 4, "%px: orig: ", addr);
- DUMP_BYTES(((u8*)&poison), 4, "%px: repl: ", addr);
+ DUMP_BYTES(ENDBR, ((u8*)addr), 4, "%px: orig: ", addr);
+ DUMP_BYTES(ENDBR, ((u8*)&poison), 4, "%px: repl: ", addr);
text_poke_early(addr, &poison, 4);
}
@@ -1150,7 +1162,7 @@ void __init_or_module alternatives_smp_m
smp->locks_end = locks_end;
smp->text = text;
smp->text_end = text_end;
- DPRINTK("locks %p -> %p, text %p -> %p, name %s\n",
+ DPRINTK(SMP, "locks %p -> %p, text %p -> %p, name %s\n",
smp->locks, smp->locks_end,
smp->text, smp->text_end, smp->name);