Unverified Commit 163e76cc authored by Guo Ren's avatar Guo Ren Committed by Palmer Dabbelt
Browse files

riscv: stack: Support HAVE_IRQ_EXIT_ON_IRQ_STACK 



Add independent irq stacks for percpu to prevent kernel stack overflows.
It is also compatible with VMAP_STACK by arch_alloc_vmap_stack.

Tested-by: default avatarJisheng Zhang <jszhang@kernel.org>
Signed-off-by: default avatarGuo Ren <guoren@linux.alibaba.com>
Signed-off-by: default avatarGuo Ren <guoren@kernel.org>
Cc: Clément Léger <cleger@rivosinc.com>
Link: https://lore.kernel.org/r/20230614013018.2168426-2-guoren@kernel.org


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent d5e45e81

arch/riscv/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -590,6 +590,13 @@ config FPU 


	  If you don't know what to do here, say Y.



config IRQ_STACKS

	bool "Independent irq stacks" if EXPERT

	default y

	select HAVE_IRQ_EXIT_ON_IRQ_STACK

	help

	  Add independent irq stacks for percpu to prevent kernel stack overflows.



endmenu # "Platform type"



menu "Kernel features"

arch/riscv/include/asm/irq_stack.h

0 → 100644
+30 −0
Original line number Diff line number Diff line 
/* SPDX-License-Identifier: GPL-2.0 */



#ifndef _ASM_RISCV_IRQ_STACK_H

#define _ASM_RISCV_IRQ_STACK_H



#include <linux/bug.h>

#include <linux/gfp.h>

#include <linux/kconfig.h>

#include <linux/vmalloc.h>

#include <linux/pgtable.h>

#include <asm/thread_info.h>



DECLARE_PER_CPU(ulong *, irq_stack_ptr);



#ifdef CONFIG_VMAP_STACK

/*

 * To ensure that VMAP'd stack overflow detection works correctly, all VMAP'd

 * stacks need to have the same alignment.

 */

static inline unsigned long *arch_alloc_vmap_stack(size_t stack_size, int node)

{

	void *p;



	p = __vmalloc_node(stack_size, THREAD_ALIGN, THREADINFO_GFP, node,

			__builtin_return_address(0));

	return kasan_reset_tag(p);

}

#endif /* CONFIG_VMAP_STACK */



#endif /* _ASM_RISCV_IRQ_STACK_H */

arch/riscv/include/asm/thread_info.h

+2 −0
Original line number Diff line number Diff line
@@ -40,6 +40,8 @@ 
#define OVERFLOW_STACK_SIZE     SZ_4K

#define SHADOW_OVERFLOW_STACK_SIZE (1024)



#define IRQ_STACK_SIZE		THREAD_SIZE



#ifndef __ASSEMBLY__



extern long shadow_stack[SHADOW_OVERFLOW_STACK_SIZE / sizeof(long)];

arch/riscv/kernel/irq.c

+33 −0
Original line number Diff line number Diff line
@@ -28,6 +28,38 @@ struct fwnode_handle *riscv_get_intc_hwnode(void) 
}

EXPORT_SYMBOL_GPL(riscv_get_intc_hwnode);



#ifdef CONFIG_IRQ_STACKS

#include <asm/irq_stack.h>



DEFINE_PER_CPU(ulong *, irq_stack_ptr);



#ifdef CONFIG_VMAP_STACK

static void init_irq_stacks(void)

{

	int cpu;

	ulong *p;



	for_each_possible_cpu(cpu) {

		p = arch_alloc_vmap_stack(IRQ_STACK_SIZE, cpu_to_node(cpu));

		per_cpu(irq_stack_ptr, cpu) = p;

	}

}

#else

/* irq stack only needs to be 16 byte aligned - not IRQ_STACK_SIZE aligned. */

DEFINE_PER_CPU_ALIGNED(ulong [IRQ_STACK_SIZE/sizeof(ulong)], irq_stack);



static void init_irq_stacks(void)

{

	int cpu;



	for_each_possible_cpu(cpu)

		per_cpu(irq_stack_ptr, cpu) = per_cpu(irq_stack, cpu);

}

#endif /* CONFIG_VMAP_STACK */

#else

static void init_irq_stacks(void) {}

#endif /* CONFIG_IRQ_STACKS */



int arch_show_interrupts(struct seq_file *p, int prec)

{

	show_ipi_stats(p, prec);
@@ -36,6 +68,7 @@ int arch_show_interrupts(struct seq_file *p, int prec) 


void __init init_IRQ(void)

{

	init_irq_stacks();

	irqchip_init();

	if (!handle_arch_irq)

		panic("No interrupt controller found.");

arch/riscv/kernel/traps.c

+33 −2
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <asm/syscall.h>

#include <asm/thread_info.h>

#include <asm/vector.h>

#include <asm/irq_stack.h>



int show_unhandled_signals = 1;
@@ -327,16 +328,46 @@ asmlinkage __visible noinstr void do_page_fault(struct pt_regs *regs) 
}

#endif



asmlinkage __visible noinstr void do_irq(struct pt_regs *regs)

static void noinstr handle_riscv_irq(struct pt_regs *regs)

{

	struct pt_regs *old_regs;

	irqentry_state_t state = irqentry_enter(regs);



	irq_enter_rcu();

	old_regs = set_irq_regs(regs);

	handle_arch_irq(regs);

	set_irq_regs(old_regs);

	irq_exit_rcu();

}



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",

		  "memory");

	} else

#endif

		handle_riscv_irq(regs);



	irqentry_exit(regs, state);

}