diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2025-04-08 00:02:14 -0700 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-04-08 09:14:11 +0200 |
| commit | fe1042b1ef79e4d5df33d5c0f0ce936493714eec (patch) | |
| tree | 30710f1b8faf6c8849840d13f1c88f0f68d42f9f /tools | |
| parent | a8df7d0ef92eca28c610206c6748daf537ac0586 (diff) | |
objtool: Split INSN_CONTEXT_SWITCH into INSN_SYSCALL and INSN_SYSRET
INSN_CONTEXT_SWITCH is ambiguous. It can represent both call semantics
(SYSCALL, SYSENTER) and return semantics (SYSRET, IRET, RETS, RETU).
Those differ significantly: calls preserve control flow whereas returns
terminate it.
Objtool uses an arbitrary rule for INSN_CONTEXT_SWITCH that almost works
by accident: if in a function, keep going; otherwise stop. It should
instead be based on the semantics of the underlying instruction.
In preparation for improving that, split INSN_CONTEXT_SWITCH into
INSN_SYCALL and INSN_SYSRET.
No functional change.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/19a76c74d2c051d3bc9a775823cafc65ad267a7a.1744095216.git.jpoimboe@kernel.org
Diffstat (limited to 'tools')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 18 | ||||
| -rw-r--r-- | tools/objtool/check.c | 6 | ||||
| -rw-r--r-- | tools/objtool/include/objtool/arch.h | 3 |
3 files changed, 17 insertions, 10 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 33d861c04ebd..3ce7b54003c2 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -522,7 +522,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec case INAT_PFX_REPNE: if (modrm == 0xca) /* eretu/erets */ - insn->type = INSN_CONTEXT_SWITCH; + insn->type = INSN_SYSRET; break; default: if (modrm == 0xca) @@ -535,11 +535,15 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec insn->type = INSN_JUMP_CONDITIONAL; - } else if (op2 == 0x05 || op2 == 0x07 || op2 == 0x34 || - op2 == 0x35) { + } else if (op2 == 0x05 || op2 == 0x34) { - /* sysenter, sysret */ - insn->type = INSN_CONTEXT_SWITCH; + /* syscall, sysenter */ + insn->type = INSN_SYSCALL; + + } else if (op2 == 0x07 || op2 == 0x35) { + + /* sysret, sysexit */ + insn->type = INSN_SYSRET; } else if (op2 == 0x0b || op2 == 0xb9) { @@ -676,7 +680,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec case 0xca: /* retf */ case 0xcb: /* retf */ - insn->type = INSN_CONTEXT_SWITCH; + insn->type = INSN_SYSRET; break; case 0xe0: /* loopne */ @@ -721,7 +725,7 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec } else if (modrm_reg == 5) { /* jmpf */ - insn->type = INSN_CONTEXT_SWITCH; + insn->type = INSN_SYSRET; } else if (modrm_reg == 6) { diff --git a/tools/objtool/check.c b/tools/objtool/check.c index c81b070ca495..2c703b960420 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3684,7 +3684,8 @@ static int validate_branch(struct objtool_file *file, struct symbol *func, break; - case INSN_CONTEXT_SWITCH: + case INSN_SYSCALL: + case INSN_SYSRET: if (func) { if (!next_insn || !next_insn->hint) { WARN_INSN(insn, "unsupported instruction in callable function"); @@ -3886,7 +3887,8 @@ static int validate_unret(struct objtool_file *file, struct instruction *insn) WARN_INSN(insn, "RET before UNTRAIN"); return 1; - case INSN_CONTEXT_SWITCH: + case INSN_SYSCALL: + case INSN_SYSRET: if (insn_func(insn)) break; return 0; diff --git a/tools/objtool/include/objtool/arch.h b/tools/objtool/include/objtool/arch.h index 089a1acc48a8..01ef6f415adf 100644 --- a/tools/objtool/include/objtool/arch.h +++ b/tools/objtool/include/objtool/arch.h @@ -19,7 +19,8 @@ enum insn_type { INSN_CALL, INSN_CALL_DYNAMIC, INSN_RETURN, - INSN_CONTEXT_SWITCH, + INSN_SYSCALL, + INSN_SYSRET, INSN_BUG, INSN_NOP, INSN_STAC, |