From: Peter Zijlstra <peterz@infradead.org>

Date: Wed, 8 Feb 2023 18:10:51 +0100

Subject: x86/alternative: Make debug-alternative selective

Git-commit: 6becb5026b8192e0ed6619d6e7793c2f1288244f

Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git#master

Patch-mainline: Queued in subsystem maintainer repository

References: bsc#1206578

Using debug-alternative generates a *LOT* of output, extend it a bit

to select which of the many rewrites it reports on.

[js] no IBT, drop the hunk

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>

Link: https://lore.kernel.org/r/20230208171431.253636689@infradead.org

Signed-off-by: Jiri Slaby <jslaby@suse.cz>

---

 arch/x86/kernel/alternative.c |   56 +++++++++++++++++++++++++-----------------

 1 file changed, 34 insertions(+), 22 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))						\

@@ -146,7 +158,7 @@ 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)

@@ -181,7 +193,7 @@ five_byte_jmp:

 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);

 }

@@ -215,7 +227,7 @@ 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;

 }

@@ -268,7 +280,7 @@ 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.

@@ -297,15 +309,15 @@ 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;

@@ -318,7 +330,7 @@ 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);

 		}

@@ -329,7 +341,7 @@ 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);

@@ -493,15 +505,15 @@ 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);

 		}

 	}

@@ -558,14 +570,14 @@ 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);

 		}

 	}

@@ -654,7 +666,7 @@ 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);