From: Peter Zijlstra peterz@infradead.org
commit f56dae88a81fded66adf2bea9922d1d98d1da14f upstream.
Turns out the compilers also generate tail calls to __sanitize_cov*(), make sure to also patch those out in noinstr code.
Fixes: 0f1441b44e82 ("objtool: Fix noinstr vs KCOV") Signed-off-by: Peter Zijlstra (Intel) peterz@infradead.org Acked-by: Marco Elver elver@google.com Link: https://lore.kernel.org/r/20210624095147.818783799@infradead.org Signed-off-by: Sasha Levin sashal@kernel.org [bwh: Backported to 5.10: - objtool doesn't have any mcount handling - Write the NOPs as hex literals since we can't use <asm/nops.h>] Signed-off-by: Ben Hutchings ben@decadent.org.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- tools/objtool/arch.h | 1 tools/objtool/arch/x86/decode.c | 20 ++++++ tools/objtool/check.c | 123 +++++++++++++++++++++------------------- 3 files changed, 86 insertions(+), 58 deletions(-)
--- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -83,6 +83,7 @@ unsigned long arch_jump_destination(stru unsigned long arch_dest_reloc_offset(int addend);
const char *arch_nop_insn(int len); +const char *arch_ret_insn(int len);
int arch_decode_hint_reg(u8 sp_reg, int *base);
--- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -586,6 +586,26 @@ const char *arch_nop_insn(int len) return nops[len-1]; }
+#define BYTE_RET 0xC3 + +const char *arch_ret_insn(int len) +{ + static const char ret[5][5] = { + { BYTE_RET }, + { BYTE_RET, 0x90 }, + { BYTE_RET, 0x66, 0x90 }, + { BYTE_RET, 0x0f, 0x1f, 0x00 }, + { BYTE_RET, 0x0f, 0x1f, 0x40, 0x00 }, + }; + + if (len < 1 || len > 5) { + WARN("invalid RET size: %d\n", len); + return NULL; + } + + return ret[len-1]; +} + /* asm/alternative.h ? */
#define ALTINSTR_FLAG_INV (1 << 15) --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -860,6 +860,60 @@ static struct reloc *insn_reloc(struct o return insn->reloc; }
+static void remove_insn_ops(struct instruction *insn) +{ + struct stack_op *op, *tmp; + + list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { + list_del(&op->list); + free(op); + } +} + +static void add_call_dest(struct objtool_file *file, struct instruction *insn, + struct symbol *dest, bool sibling) +{ + struct reloc *reloc = insn_reloc(file, insn); + + insn->call_dest = dest; + if (!dest) + return; + + if (insn->call_dest->static_call_tramp) { + list_add_tail(&insn->call_node, + &file->static_call_list); + } + + /* + * Many compilers cannot disable KCOV with a function attribute + * so they need a little help, NOP out any KCOV calls from noinstr + * text. + */ + if (insn->sec->noinstr && + !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { + if (reloc) { + reloc->type = R_NONE; + elf_write_reloc(file->elf, reloc); + } + + elf_write_insn(file->elf, insn->sec, + insn->offset, insn->len, + sibling ? arch_ret_insn(insn->len) + : arch_nop_insn(insn->len)); + + insn->type = sibling ? INSN_RETURN : INSN_NOP; + } + + /* + * Whatever stack impact regular CALLs have, should be undone + * by the RETURN of the called function. + * + * Annotated intra-function calls retain the stack_ops but + * are converted to JUMP, see read_intra_function_calls(). + */ + remove_insn_ops(insn); +} + /* * Find the destination instructions for all jumps. */ @@ -898,11 +952,7 @@ static int add_jump_destinations(struct continue; } else if (insn->func) { /* internal or external sibling call (with reloc) */ - insn->call_dest = reloc->sym; - if (insn->call_dest->static_call_tramp) { - list_add_tail(&insn->call_node, - &file->static_call_list); - } + add_call_dest(file, insn, reloc->sym, true); continue; } else if (reloc->sym->sec->idx) { dest_sec = reloc->sym->sec; @@ -958,13 +1008,8 @@ static int add_jump_destinations(struct
} else if (insn->jump_dest->func->pfunc != insn->func->pfunc && insn->jump_dest->offset == insn->jump_dest->func->offset) { - /* internal sibling call (without reloc) */ - insn->call_dest = insn->jump_dest->func; - if (insn->call_dest->static_call_tramp) { - list_add_tail(&insn->call_node, - &file->static_call_list); - } + add_call_dest(file, insn, insn->jump_dest->func, true); } } } @@ -972,16 +1017,6 @@ static int add_jump_destinations(struct return 0; }
-static void remove_insn_ops(struct instruction *insn) -{ - struct stack_op *op, *tmp; - - list_for_each_entry_safe(op, tmp, &insn->stack_ops, list) { - list_del(&op->list); - free(op); - } -} - static struct symbol *find_call_destination(struct section *sec, unsigned long offset) { struct symbol *call_dest; @@ -1000,6 +1035,7 @@ static int add_call_destinations(struct { struct instruction *insn; unsigned long dest_off; + struct symbol *dest; struct reloc *reloc;
for_each_insn(file, insn) { @@ -1009,7 +1045,9 @@ static int add_call_destinations(struct reloc = insn_reloc(file, insn); if (!reloc) { dest_off = arch_jump_destination(insn); - insn->call_dest = find_call_destination(insn->sec, dest_off); + dest = find_call_destination(insn->sec, dest_off); + + add_call_dest(file, insn, dest, false);
if (insn->ignore) continue; @@ -1027,9 +1065,8 @@ static int add_call_destinations(struct
} else if (reloc->sym->type == STT_SECTION) { dest_off = arch_dest_reloc_offset(reloc->addend); - insn->call_dest = find_call_destination(reloc->sym->sec, - dest_off); - if (!insn->call_dest) { + dest = find_call_destination(reloc->sym->sec, dest_off); + if (!dest) { WARN_FUNC("can't find call dest symbol at %s+0x%lx", insn->sec, insn->offset, reloc->sym->sec->name, @@ -1037,6 +1074,8 @@ static int add_call_destinations(struct return -1; }
+ add_call_dest(file, insn, dest, false); + } else if (arch_is_retpoline(reloc->sym)) { /* * Retpoline calls are really dynamic calls in @@ -1052,39 +1091,7 @@ static int add_call_destinations(struct continue;
} else - insn->call_dest = reloc->sym; - - if (insn->call_dest && insn->call_dest->static_call_tramp) { - list_add_tail(&insn->call_node, - &file->static_call_list); - } - - /* - * Many compilers cannot disable KCOV with a function attribute - * so they need a little help, NOP out any KCOV calls from noinstr - * text. - */ - if (insn->sec->noinstr && - !strncmp(insn->call_dest->name, "__sanitizer_cov_", 16)) { - if (reloc) { - reloc->type = R_NONE; - elf_write_reloc(file->elf, reloc); - } - - elf_write_insn(file->elf, insn->sec, - insn->offset, insn->len, - arch_nop_insn(insn->len)); - insn->type = INSN_NOP; - } - - /* - * Whatever stack impact regular CALLs have, should be undone - * by the RETURN of the called function. - * - * Annotated intra-function calls retain the stack_ops but - * are converted to JUMP, see read_intra_function_calls(). - */ - remove_insn_ops(insn); + add_call_dest(file, insn, reloc->sym, false); }
return 0;