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riscv: Deduplicate IRQ stack switching

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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 <samitolvanen@google.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Guo Ren <guoren@kernel.org>
Link: https://lore.kernel.org/r/20230927224757.1154247-10-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
This commit is contained in:
Sami Tolvanen 2023-09-27 22:48:00 +00:00 committed by Palmer Dabbelt
parent be97d0db5f
commit 82982fdd51
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GPG key ID: 2E1319F35FBB1889
6 changed files with 55 additions and 55 deletions
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5
arch/riscv/include/asm/asm.h
View file

@ -104,6 +104,11 @@
.endm
#endif /* CONFIG_SMP */
.macro load_per_cpu dst ptr tmp
asm_per_cpu \dst \ptr \tmp
REG_L \dst, 0(\dst)
.endm
/* save all GPs except x1 ~ x5 */
.macro save_from_x6_to_x31
REG_S x6, PT_T1(sp)

3
arch/riscv/include/asm/irq_stack.h
View file

@ -12,6 +12,9 @@
DECLARE_PER_CPU(ulong *, irq_stack_ptr);
asmlinkage void call_on_irq_stack(struct pt_regs *regs,
void (*func)(struct pt_regs *));
#ifdef CONFIG_VMAP_STACK
/*
* To ensure that VMAP'd stack overflow detection works correctly, all VMAP'd

5
arch/riscv/kernel/asm-offsets.c
View file

@ -14,6 +14,7 @@
#include <asm/thread_info.h>
#include <asm/ptrace.h>
#include <asm/cpu_ops_sbi.h>
#include <asm/stacktrace.h>
#include <asm/suspend.h>
void asm_offsets(void);
@ -480,4 +481,8 @@ void asm_offsets(void)
OFFSET(KERNEL_MAP_VIRT_ADDR, kernel_mapping, virt_addr);
OFFSET(SBI_HART_BOOT_TASK_PTR_OFFSET, sbi_hart_boot_data, task_ptr);
OFFSET(SBI_HART_BOOT_STACK_PTR_OFFSET, sbi_hart_boot_data, stack_ptr);
DEFINE(STACKFRAME_SIZE_ON_STACK, ALIGN(sizeof(struct stackframe), STACK_ALIGN));
OFFSET(STACKFRAME_FP, stackframe, fp);
OFFSET(STACKFRAME_RA, stackframe, ra);
}

30
arch/riscv/kernel/entry.S
View file

@ -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.

35
arch/riscv/kernel/irq.c
View file

@ -61,35 +61,16 @@ static void init_irq_stacks(void)
#endif /* CONFIG_VMAP_STACK */
#ifdef CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK
static void ___do_softirq(struct pt_regs *regs)
{
__do_softirq();
}
void do_softirq_own_stack(void)
{
#ifdef CONFIG_IRQ_STACKS
if (on_thread_stack()) {
ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
+ IRQ_STACK_SIZE/sizeof(ulong);
__asm__ __volatile(
"addi sp, sp, -"RISCV_SZPTR "\n"
REG_S" ra, (sp) \n"
"addi sp, sp, -"RISCV_SZPTR "\n"
REG_S" s0, (sp) \n"
"addi s0, sp, 2*"RISCV_SZPTR "\n"
"move sp, %[sp] \n"
"call __do_softirq \n"
"addi sp, s0, -2*"RISCV_SZPTR"\n"
REG_L" s0, (sp) \n"
"addi sp, sp, "RISCV_SZPTR "\n"
REG_L" ra, (sp) \n"
"addi sp, sp, "RISCV_SZPTR "\n"
:
: [sp] "r" (sp)
: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
"t0", "t1", "t2", "t3", "t4", "t5", "t6",
#ifndef CONFIG_FRAME_POINTER
"s0",
#endif
"memory");
} else
#endif
if (on_thread_stack())
call_on_irq_stack(NULL, ___do_softirq);
else
__do_softirq();
}
#endif /* CONFIG_HAVE_SOFTIRQ_ON_OWN_STACK */

32
arch/riscv/kernel/traps.c
View file

@ -352,34 +352,10 @@ static void noinstr handle_riscv_irq(struct pt_regs *regs)
asmlinkage void noinstr do_irq(struct pt_regs *regs)
{
irqentry_state_t state = irqentry_enter(regs);
#ifdef CONFIG_IRQ_STACKS
if (on_thread_stack()) {
ulong *sp = per_cpu(irq_stack_ptr, smp_processor_id())
+ IRQ_STACK_SIZE/sizeof(ulong);
__asm__ __volatile(
"addi sp, sp, -"RISCV_SZPTR "\n"
REG_S" ra, (sp) \n"
"addi sp, sp, -"RISCV_SZPTR "\n"
REG_S" s0, (sp) \n"
"addi s0, sp, 2*"RISCV_SZPTR "\n"
"move sp, %[sp] \n"
"move a0, %[regs] \n"
"call handle_riscv_irq \n"
"addi sp, s0, -2*"RISCV_SZPTR"\n"
REG_L" s0, (sp) \n"
"addi sp, sp, "RISCV_SZPTR "\n"
REG_L" ra, (sp) \n"
"addi sp, sp, "RISCV_SZPTR "\n"
:
: [sp] "r" (sp), [regs] "r" (regs)
: "a0", "a1", "a2", "a3", "a4", "a5", "a6", "a7",
"t0", "t1", "t2", "t3", "t4", "t5", "t6",
#ifndef CONFIG_FRAME_POINTER
"s0",
#endif
"memory");
} else
#endif
if (IS_ENABLED(CONFIG_IRQ_STACKS) && on_thread_stack())
call_on_irq_stack(regs, handle_riscv_irq);
else
handle_riscv_irq(regs);
irqentry_exit(regs, state);