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Groups > linux.kernel > #1488402
| From | Josh Poimboeuf <jpoimboe@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH v2 4/9] x86/head/32: fix the end of the stack for idle tasks |
| Date | 2016-09-21 23:10 +0200 |
| Message-ID | <sjWWd-5EH-17@gated-at.bofh.it> (permalink) |
| References | <sjWWd-5EH-5@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
The frame at the end of each idle task stack is inconsistent with real task stacks, which have a stack frame header and a real return address before the pt_regs area. This inconsistency can be confusing for stack unwinders. It also hides useful information about what asm code was involved in calling into C. Fix that by changing the initial code jumps to calls. Also add infinite loops after the calls to make it clear that the calls don't return, and to hang if they do. Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com> --- arch/x86/kernel/head_32.S | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S index 617fba2..7aac1b9 100644 --- a/arch/x86/kernel/head_32.S +++ b/arch/x86/kernel/head_32.S @@ -288,7 +288,8 @@ num_subarch_entries = (. - subarch_entries) / 4 ENTRY(start_cpu0) movl initial_stack, %ecx movl %ecx, %esp - jmp *(initial_code) + call *(initial_code) +1: jmp 1b ENDPROC(start_cpu0) #endif @@ -469,8 +470,9 @@ ENTRY(startup_32_smp) xorl %eax,%eax # Clear LDT lldt %ax - pushl $0 # fake return address for unwinder - jmp *(initial_code) + call *(initial_code) +1: jmp 1b +ENDPROC(startup_32_smp) #include "verify_cpu.S" -- 2.7.4
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[PATCH v2 0/9] x86/entry/head: standardize the end of the stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 1/9] x86/entry/head/32: use local labels Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 2/9] x86/entry/32: rename 'error_code' to 'common_exception' Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 4/9] x86/head/32: fix the end of the stack for idle tasks Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 6/9] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 7/9] x86/head: put real return address on idle task stack Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 3/9] x86/entry/32: fix the end of the stack for newly forked tasks Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200 [PATCH v2 8/9] x86/head: fix the end of the stack for idle tasks Josh Poimboeuf <jpoimboe@redhat.com> - 2016-09-21 23:10 +0200
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