Commit ac20ffbb authored by Sami Tolvanen's avatar Sami Tolvanen Committed by Will Deacon
Browse files

arm64: scs: use vmapped IRQ and SDEI shadow stacks 



Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of
using statically allocated stacks.

Signed-off-by: default avatarSami Tolvanen <samitolvanen@google.com>
Acked-by: default avatarWill Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20201130233442.2562064-3-samitolvanen@google.com


[will: Move CONFIG_SHADOW_CALL_STACK check into init_irq_scs()]
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent a2abe7cb

arch/arm64/kernel/Makefile

+0 −1
Original line number Diff line number Diff line
@@ -58,7 +58,6 @@ obj-$(CONFIG_CRASH_DUMP) += crash_dump.o 
obj-$(CONFIG_CRASH_CORE)		+= crash_core.o

obj-$(CONFIG_ARM_SDE_INTERFACE)		+= sdei.o

obj-$(CONFIG_ARM64_PTR_AUTH)		+= pointer_auth.o

obj-$(CONFIG_SHADOW_CALL_STACK)		+= scs.o

obj-$(CONFIG_ARM64_MTE)			+= mte.o



obj-y					+= vdso/ probes/

arch/arm64/kernel/entry.S

+3 −3
Original line number Diff line number Diff line
@@ -441,7 +441,7 @@ SYM_CODE_END(__swpan_exit_el0) 


#ifdef CONFIG_SHADOW_CALL_STACK

	/* also switch to the irq shadow stack */

	adr_this_cpu scs_sp, irq_shadow_call_stack, x26

	ldr_this_cpu scs_sp, irq_shadow_call_stack_ptr, x26

#endif



9998:
@@ -1097,9 +1097,9 @@ SYM_CODE_START(__sdei_asm_handler) 
#ifdef CONFIG_SHADOW_CALL_STACK

	/* Use a separate shadow call stack for normal and critical events */

	cbnz	w4, 3f

	adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal, tmp=x6

	ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6

	b	4f

3:	adr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical, tmp=x6

3:	ldr_this_cpu dst=scs_sp, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6

4:

#endif

arch/arm64/kernel/irq.c

+21 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/init.h>

#include <linux/irqchip.h>

#include <linux/kprobes.h>

#include <linux/scs.h>

#include <linux/seq_file.h>

#include <linux/vmalloc.h>

#include <asm/daifflags.h>
@@ -27,6 +28,25 @@ DEFINE_PER_CPU(struct nmi_ctx, nmi_contexts); 


DEFINE_PER_CPU(unsigned long *, irq_stack_ptr);





DECLARE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);



#ifdef CONFIG_SHADOW_CALL_STACK

DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);

#endif



static void init_irq_scs(void)

{

	int cpu;



	if (!IS_ENABLED(CONFIG_SHADOW_CALL_STACK))

		return;



	for_each_possible_cpu(cpu)

		per_cpu(irq_shadow_call_stack_ptr, cpu) =

			scs_alloc(cpu_to_node(cpu));

}



#ifdef CONFIG_VMAP_STACK

static void init_irq_stacks(void)

{
@@ -54,6 +74,7 @@ static void init_irq_stacks(void) 
void __init init_IRQ(void)

{

	init_irq_stacks();

	init_irq_scs();

	irqchip_init();

	if (!handle_arch_irq)

		panic("No interrupt controller found.");

arch/arm64/kernel/scs.c

deleted100644 → 0
+0 −16
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/*

 * Shadow Call Stack support.

 *

 * Copyright (C) 2019 Google LLC

 */



#include <linux/percpu.h>

#include <linux/scs.h>



DEFINE_SCS(irq_shadow_call_stack);



#ifdef CONFIG_ARM_SDE_INTERFACE

DEFINE_SCS(sdei_shadow_call_stack_normal);

DEFINE_SCS(sdei_shadow_call_stack_critical);

#endif

arch/arm64/kernel/sdei.c

+70 −0
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 
#include <linux/hardirq.h>

#include <linux/irqflags.h>

#include <linux/sched/task_stack.h>

#include <linux/scs.h>

#include <linux/uaccess.h>



#include <asm/alternative.h>
@@ -37,6 +38,14 @@ DEFINE_PER_CPU(unsigned long *, sdei_stack_normal_ptr); 
DEFINE_PER_CPU(unsigned long *, sdei_stack_critical_ptr);

#endif



DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);

DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);



#ifdef CONFIG_SHADOW_CALL_STACK

DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);

DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);

#endif



static void _free_sdei_stack(unsigned long * __percpu *ptr, int cpu)

{

	unsigned long *p;
@@ -90,6 +99,59 @@ static int init_sdei_stacks(void) 
	return err;

}



static void _free_sdei_scs(unsigned long * __percpu *ptr, int cpu)

{

	void *s;



	s = per_cpu(*ptr, cpu);

	if (s) {

		per_cpu(*ptr, cpu) = NULL;

		scs_free(s);

	}

}



static void free_sdei_scs(void)

{

	int cpu;



	for_each_possible_cpu(cpu) {

		_free_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu);

		_free_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu);

	}

}



static int _init_sdei_scs(unsigned long * __percpu *ptr, int cpu)

{

	void *s;



	s = scs_alloc(cpu_to_node(cpu));

	if (!s)

		return -ENOMEM;

	per_cpu(*ptr, cpu) = s;



	return 0;

}



static int init_sdei_scs(void)

{

	int cpu;

	int err = 0;



	for_each_possible_cpu(cpu) {

		err = _init_sdei_scs(&sdei_shadow_call_stack_normal_ptr, cpu);

		if (err)

			break;

		err = _init_sdei_scs(&sdei_shadow_call_stack_critical_ptr, cpu);

		if (err)

			break;

	}



	if (err)

		free_sdei_scs();



	return err;

}



static bool on_sdei_normal_stack(unsigned long sp, struct stack_info *info)

{

	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
@@ -138,6 +200,14 @@ unsigned long sdei_arch_get_entry_point(int conduit) 
			return 0;

	}



	if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK)) {

		if (init_sdei_scs()) {

			if (IS_ENABLED(CONFIG_VMAP_STACK))

				free_sdei_stacks();

			return 0;

		}

	}



	sdei_exit_mode = (conduit == SMCCC_CONDUIT_HVC) ? SDEI_EXIT_HVC : SDEI_EXIT_SMC;



#ifdef CONFIG_UNMAP_KERNEL_AT_EL0