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arm64: scs: use vmapped IRQ and SDEI shadow stacks

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

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Will 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: Will Deacon <will@kernel.org>
This commit is contained in:
Sami Tolvanen 2020-11-30 15:34:42 -08:00 committed by Will Deacon
parent a2abe7cbd8
commit ac20ffbb02
6 changed files with 94 additions and 24 deletions
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1
arch/arm64/kernel/Makefile
View file

@ -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/

6
arch/arm64/kernel/entry.S
View file

@ -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

21
arch/arm64/kernel/irq.c
View file

@ -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.");

16
arch/arm64/kernel/scs.c
View file

@ -1,16 +0,0 @@
// 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

70
arch/arm64/kernel/sdei.c
View file

@ -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

4
include/linux/scs.h
View file

@ -22,10 +22,6 @@
/* An illegal pointer value to mark the end of the shadow stack. */
#define SCS_END_MAGIC (0x5f6UL + POISON_POINTER_DELTA)
/* Allocate a static per-CPU shadow stack */
#define DEFINE_SCS(name) \
DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name) \
#define task_scs(tsk) (task_thread_info(tsk)->scs_base)
#define task_scs_sp(tsk) (task_thread_info(tsk)->scs_sp)