The following commit has been merged into the x86/entry branch of tip: Commit-ID: 300e5654198501a8cde5ad843ebad7dfbee147e4 Gitweb: https://git.kernel.org/tip/300e5654198501a8cde5ad843ebad7dfbee147e4 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Thu, 21 May 2020 22:05:47 +02:00 Committer: Ingo Molnar <mingo@xxxxxxxxxx> CommitterDate: Tue, 26 May 2020 19:06:29 +02:00 x86/entry/64: Remove IRQ stack switching ASM No more users. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Acked-by: Andy Lutomirski <luto@xxxxxxxxxx> Link: https://lore.kernel.org/r/20200521202120.021462159@xxxxxxxxxxxxx --- arch/x86/entry/entry_64.S | 96 +-------------------------------------- 1 file changed, 96 deletions(-) diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S index 389f97f..29a8a83 100644 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -370,102 +370,6 @@ SYM_CODE_END(ret_from_fork) #endif .endm -/* - * Enters the IRQ stack if we're not already using it. NMI-safe. Clobbers - * flags and puts old RSP into old_rsp, and leaves all other GPRs alone. - * Requires kernel GSBASE. - * - * The invariant is that, if irq_count != -1, then the IRQ stack is in use. - */ -.macro ENTER_IRQ_STACK regs=1 old_rsp save_ret=0 - DEBUG_ENTRY_ASSERT_IRQS_OFF - - .if \save_ret - /* - * If save_ret is set, the original stack contains one additional - * entry -- the return address. Therefore, move the address one - * entry below %rsp to \old_rsp. - */ - leaq 8(%rsp), \old_rsp - .else - movq %rsp, \old_rsp - .endif - - .if \regs - UNWIND_HINT_REGS base=\old_rsp - .endif - - incl PER_CPU_VAR(irq_count) - jnz .Lirq_stack_push_old_rsp_\@ - - /* - * Right now, if we just incremented irq_count to zero, we've - * claimed the IRQ stack but we haven't switched to it yet. - * - * If anything is added that can interrupt us here without using IST, - * it must be *extremely* careful to limit its stack usage. This - * could include kprobes and a hypothetical future IST-less #DB - * handler. - * - * The OOPS unwinder relies on the word at the top of the IRQ - * stack linking back to the previous RSP for the entire time we're - * on the IRQ stack. For this to work reliably, we need to write - * it before we actually move ourselves to the IRQ stack. - */ - - movq \old_rsp, PER_CPU_VAR(irq_stack_backing_store + IRQ_STACK_SIZE - 8) - movq PER_CPU_VAR(hardirq_stack_ptr), %rsp - -#ifdef CONFIG_DEBUG_ENTRY - /* - * If the first movq above becomes wrong due to IRQ stack layout - * changes, the only way we'll notice is if we try to unwind right - * here. Assert that we set up the stack right to catch this type - * of bug quickly. - */ - cmpq -8(%rsp), \old_rsp - je .Lirq_stack_okay\@ - ud2 - .Lirq_stack_okay\@: -#endif - -.Lirq_stack_push_old_rsp_\@: - pushq \old_rsp - - .if \regs - UNWIND_HINT_REGS indirect=1 - .endif - - .if \save_ret - /* - * Push the return address to the stack. This return address can - * be found at the "real" original RSP, which was offset by 8 at - * the beginning of this macro. - */ - pushq -8(\old_rsp) - .endif -.endm - -/* - * Undoes ENTER_IRQ_STACK. - */ -.macro LEAVE_IRQ_STACK regs=1 - DEBUG_ENTRY_ASSERT_IRQS_OFF - /* We need to be off the IRQ stack before decrementing irq_count. */ - popq %rsp - - .if \regs - UNWIND_HINT_REGS - .endif - - /* - * As in ENTER_IRQ_STACK, irq_count == 0, we are still claiming - * the irq stack but we're not on it. - */ - - decl PER_CPU_VAR(irq_count) -.endm - /** * idtentry_body - Macro to emit code calling the C function * @cfunc: C function to be called
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