From 0d0970eef3b03ef08b19da5bc3044410731cf38f Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 20 Sep 2017 16:24:32 -0500 Subject: objtool: Handle another GCC stack pointer adjustment bug The kbuild bot reported the following warning with GCC 4.4 and a randconfig: net/socket.o: warning: objtool: compat_sock_ioctl()+0x1083: stack state mismatch: cfa1=7+160 cfa2=-1+0 This is caused by another GCC non-optimization, where it backs up and restores the stack pointer for no apparent reason: 2f91: 48 89 e0 mov %rsp,%rax 2f94: 4c 89 e7 mov %r12,%rdi 2f97: 4c 89 f6 mov %r14,%rsi 2f9a: ba 20 00 00 00 mov $0x20,%edx 2f9f: 48 89 c4 mov %rax,%rsp This issue would have been happily ignored before the following commit: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") But now that objtool is paying attention to such stack pointer writes to/from a register, it needs to understand them properly. In this case that means recognizing that the "mov %rsp, %rax" instruction is potentially a backup of the stack pointer. Reported-by: kbuild test robot Signed-off-by: Josh Poimboeuf Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dmitriy Vyukov Cc: Linus Torvalds Cc: Matthias Kaehlcke Cc: Miguel Bernal Marin Cc: Peter Zijlstra Cc: Thomas Gleixner Fixes: dd88a0a0c861 ("objtool: Handle GCC stack pointer adjustment bug") Link: http://lkml.kernel.org/r/8c7aa8e9a36fbbb6655d9d8e7cea58958c912da8.1505942196.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 43 +++++++++++++++++++++++++++++-------------- 1 file changed, 29 insertions(+), 14 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index f744617c9946..a0c518ecf085 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1203,24 +1203,39 @@ static int update_insn_state(struct instruction *insn, struct insn_state *state) switch (op->src.type) { case OP_SRC_REG: - if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP) { + if (op->src.reg == CFI_SP && op->dest.reg == CFI_BP && + cfa->base == CFI_SP && + regs[CFI_BP].base == CFI_CFA && + regs[CFI_BP].offset == -cfa->offset) { + + /* mov %rsp, %rbp */ + cfa->base = op->dest.reg; + state->bp_scratch = false; + } - if (cfa->base == CFI_SP && - regs[CFI_BP].base == CFI_CFA && - regs[CFI_BP].offset == -cfa->offset) { + else if (op->src.reg == CFI_SP && + op->dest.reg == CFI_BP && state->drap) { - /* mov %rsp, %rbp */ - cfa->base = op->dest.reg; - state->bp_scratch = false; - } + /* drap: mov %rsp, %rbp */ + regs[CFI_BP].base = CFI_BP; + regs[CFI_BP].offset = -state->stack_size; + state->bp_scratch = false; + } - else if (state->drap) { + else if (op->src.reg == CFI_SP && cfa->base == CFI_SP) { - /* drap: mov %rsp, %rbp */ - regs[CFI_BP].base = CFI_BP; - regs[CFI_BP].offset = -state->stack_size; - state->bp_scratch = false; - } + /* + * mov %rsp, %reg + * + * This is needed for the rare case where GCC + * does: + * + * mov %rsp, %rax + * ... + * mov %rax, %rsp + */ + state->vals[op->dest.reg].base = CFI_CFA; + state->vals[op->dest.reg].offset = -state->stack_size; } else if (op->dest.reg == cfa->base) { -- cgit v1.3-8-gc7d7 From 00d96180dc38ef872ac471c2d3e14b067cbd895d Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Mon, 18 Sep 2017 21:43:30 -0500 Subject: objtool: Don't report end of section error after an empty unwind hint If asm code specifies an UNWIND_HINT_EMPTY hint, don't warn if the section ends unexpectedly. This can happen with the xen-head.S code because the hypercall_page is "text" but it's all zeros. Signed-off-by: Josh Poimboeuf Cc: Andy Lutomirski Cc: Boris Ostrovsky Cc: Jiri Slaby Cc: Juergen Gross Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/ddafe199dd8797e40e3c2777373347eba1d65572.1505764066.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index a0c518ecf085..83f370fa00c2 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -1752,11 +1752,14 @@ static int validate_branch(struct objtool_file *file, struct instruction *first, if (insn->dead_end) return 0; - insn = next_insn; - if (!insn) { + if (!next_insn) { + if (state.cfa.base == CFI_UNDEFINED) + return 0; WARN("%s: unexpected end of section", sec->name); return 1; } + + insn = next_insn; } return 0; -- cgit v1.3-8-gc7d7 From b703798386fb7288d5a995bd2284a984a5e24f3c Mon Sep 17 00:00:00 2001 From: Kamalesh Babulal Date: Thu, 19 Oct 2017 11:27:24 -0500 Subject: objtool: Fix memory leak in decode_instructions() When an error occurs before adding an allocated insn to the list, free it before returning. Signed-off-by: Kamalesh Babulal Signed-off-by: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/336da800bf6070eae11f4e0a3b9ca64c27658114.1508430423.git.jpoimboe@redhat.com Signed-off-by: Ingo Molnar --- tools/objtool/check.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) (limited to 'tools/objtool/check.c') diff --git a/tools/objtool/check.c b/tools/objtool/check.c index a0c518ecf085..c0e26ad1fa7e 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -267,12 +267,13 @@ static int decode_instructions(struct objtool_file *file) &insn->immediate, &insn->stack_op); if (ret) - return ret; + goto err; if (!insn->type || insn->type > INSN_LAST) { WARN_FUNC("invalid instruction type %d", insn->sec, insn->offset, insn->type); - return -1; + ret = -1; + goto err; } hash_add(file->insn_hash, &insn->hash, insn->offset); @@ -296,6 +297,10 @@ static int decode_instructions(struct objtool_file *file) } return 0; + +err: + free(insn); + return ret; } /* -- cgit v1.3-8-gc7d7