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| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-03-01 07:13:12 -0800 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-03-23 23:18:58 +0100 |
| commit | fb799447ae2974a07907906dff5bd4b9e47b7123 (patch) | |
| tree | 05f8233eb66094db1be1801c5544776674c5913a /arch/x86/entry | |
| parent | 4708ea14bef314fc901857eefd65678236a9f2d9 (diff) | |
| download | linux-fb799447ae2974a07907906dff5bd4b9e47b7123.tar.gz linux-fb799447ae2974a07907906dff5bd4b9e47b7123.tar.bz2 linux-fb799447ae2974a07907906dff5bd4b9e47b7123.zip | |
x86,objtool: Split UNWIND_HINT_EMPTY in two
Mark reported that the ORC unwinder incorrectly marks an unwind as
reliable when the unwind terminates prematurely in the dark corners of
return_to_handler() due to lack of information about the next frame.
The problem is UNWIND_HINT_EMPTY is used in two different situations:
1) The end of the kernel stack unwind before hitting user entry, boot
code, or fork entry
2) A blind spot in ORC coverage where the unwinder has to bail due to
lack of information about the next frame
The ORC unwinder has no way to tell the difference between the two.
When it encounters an undefined stack state with 'end=1', it blindly
marks the stack reliable, which can break the livepatch consistency
model.
Fix it by splitting UNWIND_HINT_EMPTY into UNWIND_HINT_UNDEFINED and
UNWIND_HINT_END_OF_STACK.
Reported-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/fd6212c8b450d3564b855e1cb48404d6277b4d9f.1677683419.git.jpoimboe@kernel.org
Diffstat (limited to 'arch/x86/entry')
| -rw-r--r-- | arch/x86/entry/entry_64.S | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 5b93eb7db0ab..45e135be2a9f 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -205,7 +205,7 @@ syscall_return_via_sysret: */ movq %rsp, %rdi movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp - UNWIND_HINT_EMPTY + UNWIND_HINT_END_OF_STACK pushq RSP-RDI(%rdi) /* RSP */ pushq (%rdi) /* RDI */ @@ -286,7 +286,7 @@ SYM_FUNC_END(__switch_to_asm) .pushsection .text, "ax" __FUNC_ALIGN SYM_CODE_START_NOALIGN(ret_from_fork) - UNWIND_HINT_EMPTY + UNWIND_HINT_END_OF_STACK ANNOTATE_NOENDBR // copy_thread CALL_DEPTH_ACCOUNT movq %rax, %rdi @@ -303,7 +303,7 @@ SYM_CODE_START_NOALIGN(ret_from_fork) 1: /* kernel thread */ - UNWIND_HINT_EMPTY + UNWIND_HINT_END_OF_STACK movq %r12, %rdi CALL_NOSPEC rbx /* @@ -643,7 +643,7 @@ SYM_INNER_LABEL(swapgs_restore_regs_and_return_to_usermode, SYM_L_GLOBAL) */ movq %rsp, %rdi movq PER_CPU_VAR(cpu_tss_rw + TSS_sp0), %rsp - UNWIND_HINT_EMPTY + UNWIND_HINT_END_OF_STACK /* Copy the IRET frame to the trampoline stack. */ pushq 6*8(%rdi) /* SS */ @@ -869,7 +869,7 @@ SYM_CODE_END(exc_xen_hypervisor_callback) */ __FUNC_ALIGN SYM_CODE_START_NOALIGN(xen_failsafe_callback) - UNWIND_HINT_EMPTY + UNWIND_HINT_UNDEFINED ENDBR movl %ds, %ecx cmpw %cx, 0x10(%rsp) @@ -1520,7 +1520,7 @@ SYM_CODE_END(asm_exc_nmi) * MSRs to fully disable 32-bit SYSCALL. */ SYM_CODE_START(ignore_sysret) - UNWIND_HINT_EMPTY + UNWIND_HINT_END_OF_STACK ENDBR mov $-ENOSYS, %eax sysretl |