x86/alternative: Make debug-alternative selective

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@infradead.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20230208171431.253636689@infradead.org

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index f615e0c..b3ae6cf 100644 (file)
--- 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(char *str)
 }
 __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 *orig_insn, u8 *repl_insn, u8 *insn_buff)
        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 @@ 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);
 }
 
@@ -217,7 +229,7 @@ static __always_inline int optimize_nops_range(u8 *instr, u8 instrlen, int off)
        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_alternatives(struct alt_instr *start,
        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_alternatives(struct alt_instr *start,
                if (!boot_cpu_has(a->cpuid) == !(a->flags & ALT_FLAG_NOT))
                        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->flags & ALT_FLAG_NOT) ? "!" : "",
                        a->cpuid >> 5,
                        a->cpuid & 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_alternatives(struct alt_instr *start,
                 */
                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_alternatives(struct alt_instr *start,
                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);
 
@@ -555,15 +567,15 @@ void __init_or_module noinline apply_retpolines(s32 *start, s32 *end)
                        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);
                }
        }
@@ -630,14 +642,14 @@ void __init_or_module noinline apply_returns(s32 *start, s32 *end)
                              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);
                }
        }
@@ -667,13 +679,13 @@ static void poison_endbr(void *addr, bool warn)
                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);
 }
 
@@ -1148,7 +1160,7 @@ 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("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);