Messages in this thread Patch in this message | | | Date | Tue, 28 Apr 2020 21:11:10 +0200 | From | Peter Zijlstra <> | Subject | [PATCH v2 09/14] objtool: Move the IRET hack into the arch decoder |
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From: Miroslav Benes <mbenes@suse.cz>
Quoting Julien:
"And the other suggestion is my other email was that you don't even need to add INSN_EXCEPTION_RETURN. You can keep IRET as INSN_CONTEXT_SWITCH by default and x86 decoder lookups the symbol conaining an iret. If it's a function symbol, it can just set the type to INSN_OTHER so that it caries on to the next instruction after having handled the stack_op."
Suggested-by: Julien Thierry <jthierry@redhat.com> Signed-off-by: Miroslav Benes <mbenes@suse.cz> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- tools/objtool/arch.h | 1 - tools/objtool/arch/x86/decode.c | 28 ++++++++++++++++++---------- tools/objtool/check.c | 11 ----------- tools/objtool/elf.c | 4 ++-- tools/objtool/elf.h | 2 +- 5 files changed, 21 insertions(+), 25 deletions(-)
--- a/tools/objtool/arch.h +++ b/tools/objtool/arch.h @@ -19,7 +19,6 @@ enum insn_type { INSN_CALL, INSN_CALL_DYNAMIC, INSN_RETURN, - INSN_EXCEPTION_RETURN, INSN_CONTEXT_SWITCH, INSN_BUG, INSN_NOP, --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -94,6 +94,7 @@ int arch_decode_instruction(const struct rex_x = 0, modrm = 0, modrm_mod = 0, modrm_rm = 0, modrm_reg = 0, sib = 0; struct stack_op *op = NULL; + struct symbol *sym; x86_64 = is_x86_64(elf); if (x86_64 == -1) @@ -469,17 +470,24 @@ int arch_decode_instruction(const struct break; case 0xcf: /* iret */ - *type = INSN_EXCEPTION_RETURN; - - ADD_OP(op) { - /* add $40, %rsp */ - op->src.type = OP_SRC_ADD; - op->src.reg = CFI_SP; - op->src.offset = 5*8; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; + /* + * Handle sync_core(), which has an IRET to self. + * All other IRET are in STT_NONE entry code. + */ + sym = find_symbol_containing(sec, offset); + if (sym && sym->type == STT_FUNC) { + ADD_OP(op) { + /* add $40, %rsp */ + op->src.type = OP_SRC_ADD; + op->src.reg = CFI_SP; + op->src.offset = 5*8; + op->dest.type = OP_DEST_REG; + op->dest.reg = CFI_SP; + } + break; } - break; + + /* fallthrough */ case 0xca: /* retf */ case 0xcb: /* retf */ --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -2308,17 +2308,6 @@ static int validate_branch(struct objtoo break; - case INSN_EXCEPTION_RETURN: - /* - * This handles x86's sync_core() case, where we use an - * IRET to self. All 'normal' IRET instructions are in - * STT_NOTYPE entry symbols. - */ - if (func) - break; - - return 0; - case INSN_CONTEXT_SWITCH: if (func && (!next_insn || !next_insn->hint)) { WARN_FUNC("unsupported instruction in callable function", --- a/tools/objtool/elf.c +++ b/tools/objtool/elf.c @@ -61,7 +61,7 @@ static void rb_add(struct rb_root *tree, rb_insert_color(node, tree); } -static struct rb_node *rb_find_first(struct rb_root *tree, const void *key, +static struct rb_node *rb_find_first(const struct rb_root *tree, const void *key, int (*cmp)(const void *key, const struct rb_node *)) { struct rb_node *node = tree->rb_node; @@ -189,7 +189,7 @@ struct symbol *find_func_by_offset(struc return NULL; } -struct symbol *find_symbol_containing(struct section *sec, unsigned long offset) +struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset) { struct rb_node *node; --- a/tools/objtool/elf.h +++ b/tools/objtool/elf.h @@ -124,7 +124,7 @@ struct section *find_section_by_name(con struct symbol *find_func_by_offset(struct section *sec, unsigned long offset); struct symbol *find_symbol_by_offset(struct section *sec, unsigned long offset); struct symbol *find_symbol_by_name(const struct elf *elf, const char *name); -struct symbol *find_symbol_containing(struct section *sec, unsigned long offset); +struct symbol *find_symbol_containing(const struct section *sec, unsigned long offset); struct rela *find_rela_by_dest(const struct elf *elf, struct section *sec, unsigned long offset); struct rela *find_rela_by_dest_range(const struct elf *elf, struct section *sec, unsigned long offset, unsigned int len);
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