diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2026-03-06 09:35:06 -0800 |
|---|---|---|
| committer | Josh Poimboeuf <jpoimboe@kernel.org> | 2026-03-09 08:45:10 -0700 |
| commit | 7fdaa640c810cb42090a182c33f905bcc47a616a (patch) | |
| tree | e5bd0269fc4677d89ecc064112b026533be390af /tools/objtool | |
| parent | 1fd1dc41724319406b0aff221a352a400b0ddfc5 (diff) | |
objtool: Handle Clang RSP musical chairs
For no apparent reason (possibly related to CONFIG_KMSAN), Clang can
randomly pass the value of RSP to other registers and then back again to
RSP. Handle that accordingly.
Fixes the following warnings:
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: undefined stack state
drivers/input/misc/uinput.o: warning: objtool: uinput_str_to_user+0x165: unknown CFA base reg -1
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/90956545-2066-46e3-b547-10c884582eb0@app.fastmail.com
Link: https://patch.msgid.link/240e6a172cc73292499334a3724d02ccb3247fc7.1772818491.git.jpoimboe@kernel.org
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Diffstat (limited to 'tools/objtool')
| -rw-r--r-- | tools/objtool/arch/x86/decode.c | 62 | ||||
| -rw-r--r-- | tools/objtool/check.c | 14 |
2 files changed, 37 insertions, 39 deletions
diff --git a/tools/objtool/arch/x86/decode.c b/tools/objtool/arch/x86/decode.c index 73bfea220d1b..c5817829cdfa 100644 --- a/tools/objtool/arch/x86/decode.c +++ b/tools/objtool/arch/x86/decode.c @@ -395,52 +395,36 @@ int arch_decode_instruction(struct objtool_file *file, const struct section *sec if (!rex_w) break; - if (modrm_reg == CFI_SP) { - - if (mod_is_reg()) { - /* mov %rsp, reg */ - ADD_OP(op) { - op->src.type = OP_SRC_REG; - op->src.reg = CFI_SP; - op->dest.type = OP_DEST_REG; - op->dest.reg = modrm_rm; - } - break; - - } else { - /* skip RIP relative displacement */ - if (is_RIP()) - break; - - /* skip nontrivial SIB */ - if (have_SIB()) { - modrm_rm = sib_base; - if (sib_index != CFI_SP) - break; - } - - /* mov %rsp, disp(%reg) */ - ADD_OP(op) { - op->src.type = OP_SRC_REG; - op->src.reg = CFI_SP; - op->dest.type = OP_DEST_REG_INDIRECT; - op->dest.reg = modrm_rm; - op->dest.offset = ins.displacement.value; - } - break; + if (mod_is_reg()) { + /* mov reg, reg */ + ADD_OP(op) { + op->src.type = OP_SRC_REG; + op->src.reg = modrm_reg; + op->dest.type = OP_DEST_REG; + op->dest.reg = modrm_rm; } - break; } - if (rm_is_reg(CFI_SP)) { + /* skip RIP relative displacement */ + if (is_RIP()) + break; - /* mov reg, %rsp */ + /* skip nontrivial SIB */ + if (have_SIB()) { + modrm_rm = sib_base; + if (sib_index != CFI_SP) + break; + } + + /* mov %rsp, disp(%reg) */ + if (modrm_reg == CFI_SP) { ADD_OP(op) { op->src.type = OP_SRC_REG; - op->src.reg = modrm_reg; - op->dest.type = OP_DEST_REG; - op->dest.reg = CFI_SP; + op->src.reg = CFI_SP; + op->dest.type = OP_DEST_REG_INDIRECT; + op->dest.reg = modrm_rm; + op->dest.offset = ins.displacement.value; } break; } diff --git a/tools/objtool/check.c b/tools/objtool/check.c index a30379e4ff97..786b2f2adbab 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -3000,6 +3000,20 @@ static int update_cfi_state(struct instruction *insn, cfi->stack_size += 8; } + else if (cfi->vals[op->src.reg].base == CFI_CFA) { + /* + * Clang RSP musical chairs: + * + * mov %rsp, %rdx [handled above] + * ... + * mov %rdx, %rbx [handled here] + * ... + * mov %rbx, %rsp [handled above] + */ + cfi->vals[op->dest.reg].base = CFI_CFA; + cfi->vals[op->dest.reg].offset = cfi->vals[op->src.reg].offset; + } + break; |