From: Mark Rutland <mark.rutland@xxxxxxx> commit f8049488e7d37b0a0e438ee449e83b3e46958743 upstream. When handling IRQ/FIQ exceptions the entry assembly may transition from a task's stack to a CPU's IRQ stack (and IRQ shadow call stack). In subsequent patches we want to migrate the IRQ/FIQ triage logic to C, and as we want to perform some actions on the task stack (e.g. EL1 preemption), we need to switch stacks within the C handler. So that we can do so, this patch adds a helper to call a function on a CPU's IRQ stack (and shadow stack as appropriate). Subsequent patches will make use of the new helper function. Signed-off-by: Mark Rutland <mark.rutland@xxxxxxx> Acked-by: Catalin Marinas <catalin.marinas@xxxxxxx> Acked-by: Marc Zyngier <maz@xxxxxxxxxx> Cc: James Morse <james.morse@xxxxxxx> Cc: Will Deacon <will@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210607094624.34689-7-mark.rutland@xxxxxxx Signed-off-by: Will Deacon <will@xxxxxxxxxx> Signed-off-by: Xiang Yang <xiangyang3@xxxxxxxxxx> --- arch/arm64/include/asm/exception.h | 2 ++ arch/arm64/kernel/entry.S | 36 ++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+) diff --git a/arch/arm64/include/asm/exception.h b/arch/arm64/include/asm/exception.h index cc5b2203d876..def53267f4a2 100644 --- a/arch/arm64/include/asm/exception.h +++ b/arch/arm64/include/asm/exception.h @@ -28,6 +28,8 @@ static inline u32 disr_to_esr(u64 disr) asmlinkage void noinstr enter_el1_irq_or_nmi(struct pt_regs *regs); asmlinkage void noinstr exit_el1_irq_or_nmi(struct pt_regs *regs); +asmlinkage void call_on_irq_stack(struct pt_regs *regs, + void (*func)(struct pt_regs *)); asmlinkage void enter_from_user_mode(void); asmlinkage void exit_to_user_mode(void); void arm64_enter_nmi(struct pt_regs *regs); diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S index 020a455824be..8b17d83e8c87 100644 --- a/arch/arm64/kernel/entry.S +++ b/arch/arm64/kernel/entry.S @@ -1043,6 +1043,42 @@ SYM_CODE_START(ret_from_fork) SYM_CODE_END(ret_from_fork) NOKPROBE(ret_from_fork) +/* + * void call_on_irq_stack(struct pt_regs *regs, + * void (*func)(struct pt_regs *)); + * + * Calls func(regs) using this CPU's irq stack and shadow irq stack. + */ +SYM_FUNC_START(call_on_irq_stack) +#ifdef CONFIG_SHADOW_CALL_STACK + stp scs_sp, xzr, [sp, #-16]! + adr_this_cpu scs_sp, irq_shadow_call_stack, x17 +#endif + /* Create a frame record to save our LR and SP (implicit in FP) */ + stp x29, x30, [sp, #-16]! + mov x29, sp + + ldr_this_cpu x16, irq_stack_ptr, x17 + mov x15, #IRQ_STACK_SIZE + add x16, x16, x15 + + /* Move to the new stack and call the function there */ + mov sp, x16 + blr x1 + + /* + * Restore the SP from the FP, and restore the FP and LR from the frame + * record. + */ + mov sp, x29 + ldp x29, x30, [sp], #16 +#ifdef CONFIG_SHADOW_CALL_STACK + ldp scs_sp, xzr, [sp], #16 +#endif + ret +SYM_FUNC_END(call_on_irq_stack) +NOKPROBE(call_on_irq_stack) + #ifdef CONFIG_ARM_SDE_INTERFACE #include <asm/sdei.h> -- 2.34.1
