| From a6cefda7f24c840569a619b5c1669c323b1f1996 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Tue, 8 Mar 2022 16:30:50 +0100 |
| Subject: x86: Annotate call_on_stack() |
| |
| From: Peter Zijlstra <peterz@infradead.org> |
| |
| [ Upstream commit be0075951fde739f14ee2b659e2fd6e2499c46c0 ] |
| |
| vmlinux.o: warning: objtool: page_fault_oops()+0x13c: unreachable instruction |
| |
| 0000 000000000005b460 <page_fault_oops>: |
| ... |
| 0128 5b588: 49 89 23 mov %rsp,(%r11) |
| 012b 5b58b: 4c 89 dc mov %r11,%rsp |
| 012e 5b58e: 4c 89 f2 mov %r14,%rdx |
| 0131 5b591: 48 89 ee mov %rbp,%rsi |
| 0134 5b594: 4c 89 e7 mov %r12,%rdi |
| 0137 5b597: e8 00 00 00 00 call 5b59c <page_fault_oops+0x13c> 5b598: R_X86_64_PLT32 handle_stack_overflow-0x4 |
| 013c 5b59c: 5c pop %rsp |
| |
| vmlinux.o: warning: objtool: sysvec_reboot()+0x6d: unreachable instruction |
| |
| 0000 00000000000033f0 <sysvec_reboot>: |
| ... |
| 005d 344d: 4c 89 dc mov %r11,%rsp |
| 0060 3450: e8 00 00 00 00 call 3455 <sysvec_reboot+0x65> 3451: R_X86_64_PLT32 irq_enter_rcu-0x4 |
| 0065 3455: 48 89 ef mov %rbp,%rdi |
| 0068 3458: e8 00 00 00 00 call 345d <sysvec_reboot+0x6d> 3459: R_X86_64_PC32 .text+0x47d0c |
| 006d 345d: e8 00 00 00 00 call 3462 <sysvec_reboot+0x72> 345e: R_X86_64_PLT32 irq_exit_rcu-0x4 |
| 0072 3462: 5c pop %rsp |
| |
| Both cases are due to a call_on_stack() calling a __noreturn function. |
| Since that's an inline asm, GCC can't do anything about the |
| instructions after the CALL. Therefore put in an explicit |
| ASM_REACHABLE annotation to make sure objtool and gcc are consistently |
| confused about control flow. |
| |
| Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> |
| Acked-by: Josh Poimboeuf <jpoimboe@redhat.com> |
| Link: https://lore.kernel.org/r/20220308154319.468805622@infradead.org |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| arch/x86/include/asm/irq_stack.h | 3 ++- |
| 1 file changed, 2 insertions(+), 1 deletion(-) |
| |
| diff --git a/arch/x86/include/asm/irq_stack.h b/arch/x86/include/asm/irq_stack.h |
| index ae9d40f6c706..05af249d6bec 100644 |
| --- a/arch/x86/include/asm/irq_stack.h |
| +++ b/arch/x86/include/asm/irq_stack.h |
| @@ -99,7 +99,8 @@ |
| } |
| |
| #define ASM_CALL_ARG0 \ |
| - "call %P[__func] \n" |
| + "call %P[__func] \n" \ |
| + ASM_REACHABLE |
| |
| #define ASM_CALL_ARG1 \ |
| "movq %[arg1], %%rdi \n" \ |
| -- |
| 2.35.1 |
| |
