From 4531ef6a8aaf132aa32e2e26670c652942540633 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 9 Oct 2019 12:26:53 +0200 Subject: [PATCH] x86/alternative: Shrink text_poke_loc Employ the fact that all text must be within a s32 displacement of one another to shrink the text_poke_loc::addr field. Make it relative to _stext. This then shrinks struct text_poke_loc to 16 bytes, and consequently increases TP_VEC_MAX from 170 to 256. Tested-by: Alexei Starovoitov Tested-by: Steven Rostedt (VMware) Signed-off-by: Peter Zijlstra (Intel) Acked-by: Alexei Starovoitov Cc: Andy Lutomirski Cc: Borislav Petkov Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Thomas Gleixner Link: https://lkml.kernel.org/r/20191111132458.047052889@infradead.org Signed-off-by: Ingo Molnar --- arch/x86/kernel/alternative.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index 6e3ee73775f6..526cc5fb7314 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -937,7 +937,7 @@ static void do_sync_core(void *info) } struct text_poke_loc { - void *addr; + s32 rel_addr; /* addr := _stext + rel_addr */ s32 rel32; u8 opcode; const u8 text[POKE_MAX_OPCODE_SIZE]; @@ -948,13 +948,18 @@ static struct bp_patching_desc { int nr_entries; } bp_patching; +static inline void *text_poke_addr(struct text_poke_loc *tp) +{ + return _stext + tp->rel_addr; +} + static int notrace patch_cmp(const void *key, const void *elt) { struct text_poke_loc *tp = (struct text_poke_loc *) elt; - if (key < tp->addr) + if (key < text_poke_addr(tp)) return -1; - if (key > tp->addr) + if (key > text_poke_addr(tp)) return 1; return 0; } @@ -1000,7 +1005,7 @@ int notrace poke_int3_handler(struct pt_regs *regs) return 0; } else { tp = bp_patching.vec; - if (tp->addr != ip) + if (text_poke_addr(tp) != ip) return 0; } @@ -1078,7 +1083,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries * First step: add a int3 trap to the address that will be patched. */ for (i = 0; i < nr_entries; i++) - text_poke(tp[i].addr, &int3, sizeof(int3)); + text_poke(text_poke_addr(&tp[i]), &int3, sizeof(int3)); on_each_cpu(do_sync_core, NULL, 1); @@ -1089,7 +1094,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries int len = text_opcode_size(tp[i].opcode); if (len - sizeof(int3) > 0) { - text_poke((char *)tp[i].addr + sizeof(int3), + text_poke(text_poke_addr(&tp[i]) + sizeof(int3), (const char *)tp[i].text + sizeof(int3), len - sizeof(int3)); do_sync++; @@ -1113,7 +1118,7 @@ static void text_poke_bp_batch(struct text_poke_loc *tp, unsigned int nr_entries if (tp[i].text[0] == INT3_INSN_OPCODE) continue; - text_poke(tp[i].addr, tp[i].text, sizeof(int3)); + text_poke(text_poke_addr(&tp[i]), tp[i].text, sizeof(int3)); do_sync++; } @@ -1143,7 +1148,7 @@ void text_poke_loc_init(struct text_poke_loc *tp, void *addr, BUG_ON(!insn_complete(&insn)); BUG_ON(len != insn.length); - tp->addr = addr; + tp->rel_addr = addr - (void *)_stext; tp->opcode = insn.opcode.bytes[0]; switch (tp->opcode) { @@ -1192,7 +1197,7 @@ static bool tp_order_fail(void *addr) return true; tp = &tp_vec[tp_vec_nr - 1]; - if ((unsigned long)tp->addr > (unsigned long)addr) + if ((unsigned long)text_poke_addr(tp) > (unsigned long)addr) return true; return false;