[PATCH 2/2] arm64: scs: use vmapped IRQ and SDEI shadow stacks
Sami Tolvanen
samitolvanen at google.com
Thu Oct 22 16:23:55 EDT 2020
Use scs_alloc() to allocate also IRQ and SDEI shadow stacks instead of
using statically allocated stacks.
Signed-off-by: Sami Tolvanen <samitolvanen at google.com>
---
arch/arm64/include/asm/scs.h | 21 ++++++++++-
arch/arm64/kernel/entry.S | 6 ++--
arch/arm64/kernel/irq.c | 2 ++
arch/arm64/kernel/scs.c | 67 +++++++++++++++++++++++++++++++++---
arch/arm64/kernel/sdei.c | 7 ++++
include/linux/scs.h | 8 ++---
kernel/scs.c | 4 +--
7 files changed, 101 insertions(+), 14 deletions(-)
diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h
index eaa2cd92e4c1..e9d2c3e67ff9 100644
--- a/arch/arm64/include/asm/scs.h
+++ b/arch/arm64/include/asm/scs.h
@@ -24,6 +24,25 @@
.endm
#endif /* CONFIG_SHADOW_CALL_STACK */
-#endif /* __ASSEMBLY __ */
+#else /* __ASSEMBLY__ */
+
+#include <linux/scs.h>
+
+#ifdef CONFIG_SHADOW_CALL_STACK
+
+extern void scs_init_irq(void);
+
+extern void scs_free_sdei(void);
+extern int scs_init_sdei(void);
+
+#else
+
+static inline void scs_init_irq(void) {}
+static inline void scs_free_sdei(void) {}
+static inline int scs_init_sdei(void) { return -EOPNOTSUPP; }
+
+#endif
+
+#endif /* __ASSEMBLY__ */
#endif /* _ASM_SCS_H */
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index f30007dff35f..0f76fe8142e4 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -438,7 +438,7 @@ 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:
@@ -1094,9 +1094,9 @@ 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
diff --git a/arch/arm64/kernel/irq.c b/arch/arm64/kernel/irq.c
index 9cf2fb87584a..54ba3725bc0e 100644
--- a/arch/arm64/kernel/irq.c
+++ b/arch/arm64/kernel/irq.c
@@ -20,6 +20,7 @@
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <asm/daifflags.h>
+#include <asm/scs.h>
#include <asm/vmap_stack.h>
/* Only access this in an NMI enter/exit */
@@ -54,6 +55,7 @@ static void init_irq_stacks(void)
void __init init_IRQ(void)
{
init_irq_stacks();
+ scs_init_irq();
irqchip_init();
if (!handle_arch_irq)
panic("No interrupt controller found.");
diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c
index e8f7ff45dd8f..f85cebf8122a 100644
--- a/arch/arm64/kernel/scs.c
+++ b/arch/arm64/kernel/scs.c
@@ -6,11 +6,70 @@
*/
#include <linux/percpu.h>
-#include <linux/scs.h>
+#include <asm/scs.h>
-DEFINE_SCS(irq_shadow_call_stack);
+DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
+
+DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
+DECLARE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
#ifdef CONFIG_ARM_SDE_INTERFACE
-DEFINE_SCS(sdei_shadow_call_stack_normal);
-DEFINE_SCS(sdei_shadow_call_stack_critical);
+DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_normal_ptr);
+DEFINE_PER_CPU(unsigned long *, sdei_shadow_call_stack_critical_ptr);
#endif
+
+void scs_init_irq(void)
+{
+ int cpu;
+
+ for_each_possible_cpu(cpu)
+ per_cpu(irq_shadow_call_stack_ptr, cpu) =
+ scs_alloc(cpu_to_node(cpu));
+}
+
+
+void scs_free_sdei(void)
+{
+ int cpu;
+ void *s;
+
+ if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
+ return;
+
+ for_each_possible_cpu(cpu) {
+ s = per_cpu(sdei_shadow_call_stack_normal_ptr, cpu);
+ if (s)
+ scs_free(s);
+
+ s = per_cpu(sdei_shadow_call_stack_critical_ptr, cpu);
+ if (s)
+ scs_free(s);
+ }
+}
+
+int scs_init_sdei(void)
+{
+ int cpu;
+ void *s;
+
+ if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
+ return 0;
+
+ for_each_possible_cpu(cpu) {
+ s = scs_alloc(cpu_to_node(cpu));
+ if (!s)
+ goto err;
+ per_cpu(sdei_shadow_call_stack_normal_ptr, cpu) = s;
+
+ s = scs_alloc(cpu_to_node(cpu));
+ if (!s)
+ goto err;
+ per_cpu(sdei_shadow_call_stack_critical_ptr, cpu) = s;
+ }
+
+ return 0;
+
+err:
+ scs_free_sdei();
+ return -ENOMEM;
+}
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 7689f2031c0c..04519a7cb51d 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -13,6 +13,7 @@
#include <asm/kprobes.h>
#include <asm/mmu.h>
#include <asm/ptrace.h>
+#include <asm/scs.h>
#include <asm/sections.h>
#include <asm/stacktrace.h>
#include <asm/sysreg.h>
@@ -138,6 +139,12 @@ unsigned long sdei_arch_get_entry_point(int conduit)
return 0;
}
+ if (scs_init_sdei()) {
+ 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
diff --git a/include/linux/scs.h b/include/linux/scs.h
index 86e3c4b7b714..6b35a83576d4 100644
--- a/include/linux/scs.h
+++ b/include/linux/scs.h
@@ -21,13 +21,11 @@
/* 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)
+void *scs_alloc(int node);
+void scs_free(void *s);
void scs_init(void);
int scs_prepare(struct task_struct *tsk, int node);
void scs_release(struct task_struct *tsk);
@@ -56,6 +54,8 @@ static inline bool task_scs_end_corrupted(struct task_struct *tsk)
#else /* CONFIG_SHADOW_CALL_STACK */
+static inline void *scs_alloc(int node) { return NULL; }
+static inline void scs_free(void *s) {}
static inline void scs_init(void) {}
static inline void scs_task_reset(struct task_struct *tsk) {}
static inline int scs_prepare(struct task_struct *tsk, int node) { return 0; }
diff --git a/kernel/scs.c b/kernel/scs.c
index 2136edba548d..8df4a92cd939 100644
--- a/kernel/scs.c
+++ b/kernel/scs.c
@@ -24,7 +24,7 @@ static void __scs_account(void *s, int account)
#define NR_CACHED_SCS 2
static DEFINE_PER_CPU(void *, scs_cache[NR_CACHED_SCS]);
-static void *scs_alloc(int node)
+void *scs_alloc(int node)
{
int i;
void *s;
@@ -63,7 +63,7 @@ static void *scs_alloc(int node)
return s;
}
-static void scs_free(void *s)
+void scs_free(void *s)
{
int i;
--
2.29.0.rc1.297.gfa9743e501-goog
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