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Groups > linux.kernel > #1166375
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [RFC/INCOMPLETE 10/13] x86/asm/entry/64: Save all regs on interrupt entry |
| Date | 2015-06-16 22:30 +0200 |
| Message-ID | <pC5EB-4Oe-3@gated-at.bofh.it> (permalink) |
| References | <pC5uV-4CR-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
To prepare for the big rewrite of the error and interrupt exit paths, we will need pt_regs completely filled in. It's already completely filled in when error_exit runs, so rearrange interrupt handling to match it. This will slow down interrupt handling very slightly (eight instructions), but the simplification it enables will be more than worth it. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/entry/entry_64.S | 29 +++++++++-------------------- 1 file changed, 9 insertions(+), 20 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index a5044d7a9d43..43bf5762443c 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -501,21 +501,13 @@ END(irq_entries_start) /* 0(%rsp): ~(interrupt number) */ .macro interrupt func cld - /* - * Since nothing in interrupt handling code touches r12...r15 members - * of "struct pt_regs", and since interrupts can nest, we can save - * four stack slots and simultaneously provide - * an unwind-friendly stack layout by saving "truncated" pt_regs - * exactly up to rbp slot, without these members. - */ - ALLOC_PT_GPREGS_ON_STACK -RBP - SAVE_C_REGS -RBP - /* this goes to 0(%rsp) for unwinder, not for saving the value: */ - SAVE_EXTRA_REGS_RBP -RBP + ALLOC_PT_GPREGS_ON_STACK + SAVE_C_REGS + SAVE_EXTRA_REGS - leaq -RBP(%rsp), %rdi /* arg1 for \func (pointer to pt_regs) */ + movq %rsp,%rdi /* arg1 for \func (pointer to pt_regs) */ - testb $3, CS-RBP(%rsp) + testb $3, CS(%rsp) jz 1f SWAPGS 1: @@ -552,9 +544,7 @@ ret_from_intr: decl PER_CPU_VAR(irq_count) /* Restore saved previous stack */ - popq %rsi - /* return code expects complete pt_regs - adjust rsp accordingly: */ - leaq -RBP(%rsi), %rsp + popq %rsp testb $3, CS(%rsp) jz retint_kernel @@ -579,7 +569,7 @@ retint_swapgs: /* return to user-space */ TRACE_IRQS_IRETQ SWAPGS - jmp restore_c_regs_and_iret + jmp restore_regs_and_iret /* Returning to kernel space */ retint_kernel: @@ -603,6 +593,8 @@ retint_kernel: * At this label, code paths which return to kernel and to user, * which come from interrupts/exception and from syscalls, merge. */ +restore_regs_and_iret: + RESTORE_EXTRA_REGS restore_c_regs_and_iret: RESTORE_C_REGS REMOVE_PT_GPREGS_FROM_STACK 8 @@ -673,12 +665,10 @@ retint_signal: jz retint_swapgs TRACE_IRQS_ON ENABLE_INTERRUPTS(CLBR_NONE) - SAVE_EXTRA_REGS movq $-1, ORIG_RAX(%rsp) xorl %esi, %esi /* oldset */ movq %rsp, %rdi /* &pt_regs */ call do_notify_resume - RESTORE_EXTRA_REGS DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF GET_THREAD_INFO(%rcx) @@ -1158,7 +1148,6 @@ END(error_entry) */ ENTRY(error_exit) movl %ebx, %eax - RESTORE_EXTRA_REGS DISABLE_INTERRUPTS(CLBR_NONE) TRACE_IRQS_OFF testl %eax, %eax -- 2.4.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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[RFC/INCOMPLETE 00/13] x86: Rewrite exit-to-userspace code Andy Lutomirski <luto@kernel.org> - 2015-06-16 22:20 +0200 [RFC/INCOMPLETE 10/13] x86/asm/entry/64: Save all regs on interrupt entry Andy Lutomirski <luto@kernel.org> - 2015-06-16 22:30 +0200 [RFC/INCOMPLETE 09/13] x86/entry/compat: Migrate compat syscalls to new exit hooks Andy Lutomirski <luto@kernel.org> - 2015-06-16 22:30 +0200 [RFC/INCOMPLETE 11/13] x86/asm/entry/64: Simplify irq stack pt_regs handling Andy Lutomirski <luto@kernel.org> - 2015-06-16 22:30 +0200
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