From 82982fdd5133fa7e0b2dfaf746d18d6f29922b82 Mon Sep 17 00:00:00 2001 From: Sami Tolvanen Date: Wed, 27 Sep 2023 22:48:00 +0000 Subject: riscv: Deduplicate IRQ stack switching With CONFIG_IRQ_STACKS, we switch to a separate per-CPU IRQ stack before calling handle_riscv_irq or __do_softirq. We currently have duplicate inline assembly snippets for stack switching in both code paths. Now that we can access per-CPU variables in assembly, implement call_on_irq_stack in assembly, and use that instead of redundant inline assembly. Signed-off-by: Sami Tolvanen Tested-by: Nathan Chancellor Reviewed-by: Guo Ren Link: https://lore.kernel.org/r/20230927224757.1154247-10-samitolvanen@google.com Signed-off-by: Palmer Dabbelt --- arch/riscv/kernel/entry.S | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) (limited to 'arch/riscv/kernel/entry.S') diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index 3d11aa3af105..a306562636e4 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -218,6 +218,36 @@ SYM_CODE_START(ret_from_fork) tail syscall_exit_to_user_mode SYM_CODE_END(ret_from_fork) +#ifdef CONFIG_IRQ_STACKS +/* + * void call_on_irq_stack(struct pt_regs *regs, + * void (*func)(struct pt_regs *)); + * + * Calls func(regs) using the per-CPU IRQ stack. + */ +SYM_FUNC_START(call_on_irq_stack) + /* Create a frame record to save ra and s0 (fp) */ + addi sp, sp, -STACKFRAME_SIZE_ON_STACK + REG_S ra, STACKFRAME_RA(sp) + REG_S s0, STACKFRAME_FP(sp) + addi s0, sp, STACKFRAME_SIZE_ON_STACK + + /* Switch to the per-CPU IRQ stack and call the handler */ + load_per_cpu t0, irq_stack_ptr, t1 + li t1, IRQ_STACK_SIZE + add sp, t0, t1 + jalr a1 + + /* Switch back to the thread stack and restore ra and s0 */ + addi sp, s0, -STACKFRAME_SIZE_ON_STACK + REG_L ra, STACKFRAME_RA(sp) + REG_L s0, STACKFRAME_FP(sp) + addi sp, sp, STACKFRAME_SIZE_ON_STACK + + ret +SYM_FUNC_END(call_on_irq_stack) +#endif /* CONFIG_IRQ_STACKS */ + /* * Integer register context switch * The callee-saved registers must be saved and restored. -- cgit v1.2.3