[v6,15/15] arm64: scs: add shadow stacks for SDEI
diff mbox series

Message ID 20191206221351.38241-16-samitolvanen@google.com
State New
Headers show
Series
  • [v6,01/15] arm64: mm: avoid x18 in idmap_kpti_install_ng_mappings
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Commit Message

Sami Tolvanen Dec. 6, 2019, 10:13 p.m. UTC
This change adds per-CPU shadow call stacks for the SDEI handler.
Similarly to how the kernel stacks are handled, we add separate shadow
stacks for normal and critical events.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/arm64/include/asm/scs.h |   2 +
 arch/arm64/kernel/entry.S    |  14 ++++-
 arch/arm64/kernel/scs.c      | 106 +++++++++++++++++++++++++++++------
 arch/arm64/kernel/sdei.c     |   7 +++
 4 files changed, 112 insertions(+), 17 deletions(-)

Comments

Will Deacon Jan. 16, 2020, 5:48 p.m. UTC | #1
[+James, since this needs his Ack before it can be merged]

On Fri, Dec 06, 2019 at 02:13:51PM -0800, Sami Tolvanen wrote:
> This change adds per-CPU shadow call stacks for the SDEI handler.
> Similarly to how the kernel stacks are handled, we add separate shadow
> stacks for normal and critical events.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
> ---
>  arch/arm64/include/asm/scs.h |   2 +
>  arch/arm64/kernel/entry.S    |  14 ++++-
>  arch/arm64/kernel/scs.c      | 106 +++++++++++++++++++++++++++++------
>  arch/arm64/kernel/sdei.c     |   7 +++
>  4 files changed, 112 insertions(+), 17 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h
> index c50d2b0c6c5f..8e327e14bc15 100644
> --- a/arch/arm64/include/asm/scs.h
> +++ b/arch/arm64/include/asm/scs.h
> @@ -9,6 +9,7 @@
>  #ifdef CONFIG_SHADOW_CALL_STACK
>  
>  extern void scs_init_irq(void);
> +extern int scs_init_sdei(void);
>  
>  static __always_inline void scs_save(struct task_struct *tsk)
>  {
> @@ -27,6 +28,7 @@ static inline void scs_overflow_check(struct task_struct *tsk)
>  #else /* CONFIG_SHADOW_CALL_STACK */
>  
>  static inline void scs_init_irq(void) {}
> +static inline int scs_init_sdei(void) { return 0; }
>  static inline void scs_save(struct task_struct *tsk) {}
>  static inline void scs_overflow_check(struct task_struct *tsk) {}
>  
> diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
> index 7aa2d366b2df..9327c3d21b64 100644
> --- a/arch/arm64/kernel/entry.S
> +++ b/arch/arm64/kernel/entry.S
> @@ -1048,13 +1048,16 @@ ENTRY(__sdei_asm_handler)
>  
>  	mov	x19, x1
>  
> +#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK)
> +	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]
> +#endif
> +
>  #ifdef CONFIG_VMAP_STACK
>  	/*
>  	 * entry.S may have been using sp as a scratch register, find whether
>  	 * this is a normal or critical event and switch to the appropriate
>  	 * stack for this CPU.
>  	 */
> -	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]
>  	cbnz	w4, 1f
>  	ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6
>  	b	2f
> @@ -1064,6 +1067,15 @@ ENTRY(__sdei_asm_handler)
>  	mov	sp, x5
>  #endif
>  
> +#ifdef CONFIG_SHADOW_CALL_STACK
> +	/* Use a separate shadow call stack for normal and critical events */
> +	cbnz	w4, 3f
> +	ldr_this_cpu dst=x18, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6
> +	b	4f
> +3:	ldr_this_cpu dst=x18, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6
> +4:
> +#endif
> +
>  	/*
>  	 * We may have interrupted userspace, or a guest, or exit-from or
>  	 * return-to either of these. We can't trust sp_el0, restore it.
> diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c
> index eaadf5430baa..dddb7c56518b 100644
> --- a/arch/arm64/kernel/scs.c
> +++ b/arch/arm64/kernel/scs.c
> @@ -10,31 +10,105 @@
>  #include <asm/pgtable.h>
>  #include <asm/scs.h>
>  
> -DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
> +#define DECLARE_SCS(name)						\
> +	DECLARE_PER_CPU(unsigned long *, name ## _ptr);			\
> +	DECLARE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name)
>  
> -#ifndef CONFIG_SHADOW_CALL_STACK_VMAP
> -DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], irq_shadow_call_stack)
> -	__aligned(SCS_SIZE);
> +#ifdef CONFIG_SHADOW_CALL_STACK_VMAP
> +#define DEFINE_SCS(name)						\
> +	DEFINE_PER_CPU(unsigned long *, name ## _ptr)
> +#else
> +/* Allocate a static per-CPU shadow stack */
> +#define DEFINE_SCS(name)						\
> +	DEFINE_PER_CPU(unsigned long *, name ## _ptr);			\
> +	DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name)	\
> +		__aligned(SCS_SIZE)
> +#endif /* CONFIG_SHADOW_CALL_STACK_VMAP */
> +
> +DECLARE_SCS(irq_shadow_call_stack);
> +DECLARE_SCS(sdei_shadow_call_stack_normal);
> +DECLARE_SCS(sdei_shadow_call_stack_critical);
> +
> +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
>  
> +static int scs_alloc_percpu(unsigned long * __percpu *ptr, int cpu)
> +{
> +	unsigned long *p;
> +
> +	p = __vmalloc_node_range(PAGE_SIZE, SCS_SIZE,
> +				 VMALLOC_START, VMALLOC_END,
> +				 GFP_SCS, PAGE_KERNEL,
> +				 0, cpu_to_node(cpu),
> +				 __builtin_return_address(0));
> +
> +	if (!p)
> +		return -ENOMEM;
> +	per_cpu(*ptr, cpu) = p;
> +
> +	return 0;
> +}
> +
> +static void scs_free_percpu(unsigned long * __percpu *ptr, int cpu)
> +{
> +	unsigned long *p = per_cpu(*ptr, cpu);
> +
> +	if (p) {
> +		per_cpu(*ptr, cpu) = NULL;
> +		vfree(p);
> +	}
> +}
> +
> +static void scs_free_sdei(void)
> +{
> +	int cpu;
> +
> +	for_each_possible_cpu(cpu) {
> +		scs_free_percpu(&sdei_shadow_call_stack_normal_ptr, cpu);
> +		scs_free_percpu(&sdei_shadow_call_stack_critical_ptr, cpu);
> +	}
> +}
> +
>  void scs_init_irq(void)
>  {
>  	int cpu;
>  
>  	for_each_possible_cpu(cpu) {
> -#ifdef CONFIG_SHADOW_CALL_STACK_VMAP
> -		unsigned long *p;
> +		if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK_VMAP))
> +			WARN_ON(scs_alloc_percpu(&irq_shadow_call_stack_ptr,
> +						 cpu));
> +		else
> +			per_cpu(irq_shadow_call_stack_ptr, cpu) =
> +				per_cpu(irq_shadow_call_stack, cpu);
> +	}
> +}
>  
> -		p = __vmalloc_node_range(PAGE_SIZE, SCS_SIZE,
> -					 VMALLOC_START, VMALLOC_END,
> -					 GFP_SCS, PAGE_KERNEL,
> -					 0, cpu_to_node(cpu),
> -					 __builtin_return_address(0));
> +int scs_init_sdei(void)
> +{
> +	int cpu;
>  
> -		per_cpu(irq_shadow_call_stack_ptr, cpu) = p;
> -#else
> -		per_cpu(irq_shadow_call_stack_ptr, cpu) =
> -			per_cpu(irq_shadow_call_stack, cpu);
> -#endif /* CONFIG_SHADOW_CALL_STACK_VMAP */
> +	if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
> +		return 0;
> +
> +	for_each_possible_cpu(cpu) {
> +		if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK_VMAP)) {
> +			if (scs_alloc_percpu(
> +				&sdei_shadow_call_stack_normal_ptr, cpu) ||
> +			    scs_alloc_percpu(
> +				&sdei_shadow_call_stack_critical_ptr, cpu)) {
> +				scs_free_sdei();
> +				return -ENOMEM;
> +			}
> +		} else {
> +			per_cpu(sdei_shadow_call_stack_normal_ptr, cpu) =
> +				per_cpu(sdei_shadow_call_stack_normal, cpu);
> +			per_cpu(sdei_shadow_call_stack_critical_ptr, cpu) =
> +				per_cpu(sdei_shadow_call_stack_critical, cpu);
> +		}
>  	}
> +
> +	return 0;
>  }
> diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
> index d6259dac62b6..2854b9f7760a 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>
> @@ -162,6 +163,12 @@ 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
> -- 
> 2.24.0.393.g34dc348eaf-goog
>

Patch
diff mbox series

diff --git a/arch/arm64/include/asm/scs.h b/arch/arm64/include/asm/scs.h
index c50d2b0c6c5f..8e327e14bc15 100644
--- a/arch/arm64/include/asm/scs.h
+++ b/arch/arm64/include/asm/scs.h
@@ -9,6 +9,7 @@ 
 #ifdef CONFIG_SHADOW_CALL_STACK
 
 extern void scs_init_irq(void);
+extern int scs_init_sdei(void);
 
 static __always_inline void scs_save(struct task_struct *tsk)
 {
@@ -27,6 +28,7 @@  static inline void scs_overflow_check(struct task_struct *tsk)
 #else /* CONFIG_SHADOW_CALL_STACK */
 
 static inline void scs_init_irq(void) {}
+static inline int scs_init_sdei(void) { return 0; }
 static inline void scs_save(struct task_struct *tsk) {}
 static inline void scs_overflow_check(struct task_struct *tsk) {}
 
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index 7aa2d366b2df..9327c3d21b64 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -1048,13 +1048,16 @@  ENTRY(__sdei_asm_handler)
 
 	mov	x19, x1
 
+#if defined(CONFIG_VMAP_STACK) || defined(CONFIG_SHADOW_CALL_STACK)
+	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]
+#endif
+
 #ifdef CONFIG_VMAP_STACK
 	/*
 	 * entry.S may have been using sp as a scratch register, find whether
 	 * this is a normal or critical event and switch to the appropriate
 	 * stack for this CPU.
 	 */
-	ldrb	w4, [x19, #SDEI_EVENT_PRIORITY]
 	cbnz	w4, 1f
 	ldr_this_cpu dst=x5, sym=sdei_stack_normal_ptr, tmp=x6
 	b	2f
@@ -1064,6 +1067,15 @@  ENTRY(__sdei_asm_handler)
 	mov	sp, x5
 #endif
 
+#ifdef CONFIG_SHADOW_CALL_STACK
+	/* Use a separate shadow call stack for normal and critical events */
+	cbnz	w4, 3f
+	ldr_this_cpu dst=x18, sym=sdei_shadow_call_stack_normal_ptr, tmp=x6
+	b	4f
+3:	ldr_this_cpu dst=x18, sym=sdei_shadow_call_stack_critical_ptr, tmp=x6
+4:
+#endif
+
 	/*
 	 * We may have interrupted userspace, or a guest, or exit-from or
 	 * return-to either of these. We can't trust sp_el0, restore it.
diff --git a/arch/arm64/kernel/scs.c b/arch/arm64/kernel/scs.c
index eaadf5430baa..dddb7c56518b 100644
--- a/arch/arm64/kernel/scs.c
+++ b/arch/arm64/kernel/scs.c
@@ -10,31 +10,105 @@ 
 #include <asm/pgtable.h>
 #include <asm/scs.h>
 
-DEFINE_PER_CPU(unsigned long *, irq_shadow_call_stack_ptr);
+#define DECLARE_SCS(name)						\
+	DECLARE_PER_CPU(unsigned long *, name ## _ptr);			\
+	DECLARE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name)
 
-#ifndef CONFIG_SHADOW_CALL_STACK_VMAP
-DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], irq_shadow_call_stack)
-	__aligned(SCS_SIZE);
+#ifdef CONFIG_SHADOW_CALL_STACK_VMAP
+#define DEFINE_SCS(name)						\
+	DEFINE_PER_CPU(unsigned long *, name ## _ptr)
+#else
+/* Allocate a static per-CPU shadow stack */
+#define DEFINE_SCS(name)						\
+	DEFINE_PER_CPU(unsigned long *, name ## _ptr);			\
+	DEFINE_PER_CPU(unsigned long [SCS_SIZE/sizeof(long)], name)	\
+		__aligned(SCS_SIZE)
+#endif /* CONFIG_SHADOW_CALL_STACK_VMAP */
+
+DECLARE_SCS(irq_shadow_call_stack);
+DECLARE_SCS(sdei_shadow_call_stack_normal);
+DECLARE_SCS(sdei_shadow_call_stack_critical);
+
+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
 
+static int scs_alloc_percpu(unsigned long * __percpu *ptr, int cpu)
+{
+	unsigned long *p;
+
+	p = __vmalloc_node_range(PAGE_SIZE, SCS_SIZE,
+				 VMALLOC_START, VMALLOC_END,
+				 GFP_SCS, PAGE_KERNEL,
+				 0, cpu_to_node(cpu),
+				 __builtin_return_address(0));
+
+	if (!p)
+		return -ENOMEM;
+	per_cpu(*ptr, cpu) = p;
+
+	return 0;
+}
+
+static void scs_free_percpu(unsigned long * __percpu *ptr, int cpu)
+{
+	unsigned long *p = per_cpu(*ptr, cpu);
+
+	if (p) {
+		per_cpu(*ptr, cpu) = NULL;
+		vfree(p);
+	}
+}
+
+static void scs_free_sdei(void)
+{
+	int cpu;
+
+	for_each_possible_cpu(cpu) {
+		scs_free_percpu(&sdei_shadow_call_stack_normal_ptr, cpu);
+		scs_free_percpu(&sdei_shadow_call_stack_critical_ptr, cpu);
+	}
+}
+
 void scs_init_irq(void)
 {
 	int cpu;
 
 	for_each_possible_cpu(cpu) {
-#ifdef CONFIG_SHADOW_CALL_STACK_VMAP
-		unsigned long *p;
+		if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK_VMAP))
+			WARN_ON(scs_alloc_percpu(&irq_shadow_call_stack_ptr,
+						 cpu));
+		else
+			per_cpu(irq_shadow_call_stack_ptr, cpu) =
+				per_cpu(irq_shadow_call_stack, cpu);
+	}
+}
 
-		p = __vmalloc_node_range(PAGE_SIZE, SCS_SIZE,
-					 VMALLOC_START, VMALLOC_END,
-					 GFP_SCS, PAGE_KERNEL,
-					 0, cpu_to_node(cpu),
-					 __builtin_return_address(0));
+int scs_init_sdei(void)
+{
+	int cpu;
 
-		per_cpu(irq_shadow_call_stack_ptr, cpu) = p;
-#else
-		per_cpu(irq_shadow_call_stack_ptr, cpu) =
-			per_cpu(irq_shadow_call_stack, cpu);
-#endif /* CONFIG_SHADOW_CALL_STACK_VMAP */
+	if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
+		return 0;
+
+	for_each_possible_cpu(cpu) {
+		if (IS_ENABLED(CONFIG_SHADOW_CALL_STACK_VMAP)) {
+			if (scs_alloc_percpu(
+				&sdei_shadow_call_stack_normal_ptr, cpu) ||
+			    scs_alloc_percpu(
+				&sdei_shadow_call_stack_critical_ptr, cpu)) {
+				scs_free_sdei();
+				return -ENOMEM;
+			}
+		} else {
+			per_cpu(sdei_shadow_call_stack_normal_ptr, cpu) =
+				per_cpu(sdei_shadow_call_stack_normal, cpu);
+			per_cpu(sdei_shadow_call_stack_critical_ptr, cpu) =
+				per_cpu(sdei_shadow_call_stack_critical, cpu);
+		}
 	}
+
+	return 0;
 }
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index d6259dac62b6..2854b9f7760a 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>
@@ -162,6 +163,12 @@  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