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Subject[PATCHv3 1/2] arm64: Add stack information to on_accessible_stack
Date

In preparation for enabling the stackleak plugin on arm64,
we need a way to get the bounds of the current stack. Extend
on_accessible_stack to get this information.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Laura Abbott <labbott@redhat.com>
---
v3: Switched some logic to reduce if nesting
---
arch/arm64/include/asm/sdei.h | 9 ++--
arch/arm64/include/asm/stacktrace.h | 73 ++++++++++++++++++++++++-----
arch/arm64/kernel/ptrace.c | 2 +-
arch/arm64/kernel/sdei.c | 51 ++++++++++++++++----
arch/arm64/kernel/stacktrace.c | 2 +-
5 files changed, 112 insertions(+), 25 deletions(-)

diff --git a/arch/arm64/include/asm/sdei.h b/arch/arm64/include/asm/sdei.h
index e073e6886685..ffe47d766c25 100644
--- a/arch/arm64/include/asm/sdei.h
+++ b/arch/arm64/include/asm/sdei.h
@@ -40,15 +40,18 @@ asmlinkage unsigned long __sdei_handler(struct pt_regs *regs,
unsigned long sdei_arch_get_entry_point(int conduit);
#define sdei_arch_get_entry_point(x) sdei_arch_get_entry_point(x)

-bool _on_sdei_stack(unsigned long sp);
-static inline bool on_sdei_stack(unsigned long sp)
+struct stack_info;
+
+bool _on_sdei_stack(unsigned long sp, struct stack_info *info);
+static inline bool on_sdei_stack(unsigned long sp,
+ struct stack_info *info)
{
if (!IS_ENABLED(CONFIG_VMAP_STACK))
return false;
if (!IS_ENABLED(CONFIG_ARM_SDE_INTERFACE))
return false;
if (in_nmi())
- return _on_sdei_stack(sp);
+ return _on_sdei_stack(sp, info);

return false;
}
diff --git a/arch/arm64/include/asm/stacktrace.h b/arch/arm64/include/asm/stacktrace.h
index 902f9edacbea..e86737b7c924 100644
--- a/arch/arm64/include/asm/stacktrace.h
+++ b/arch/arm64/include/asm/stacktrace.h
@@ -32,6 +32,21 @@ struct stackframe {
#endif
};

+enum stack_type {
+ STACK_TYPE_UNKNOWN,
+ STACK_TYPE_TASK,
+ STACK_TYPE_IRQ,
+ STACK_TYPE_OVERFLOW,
+ STACK_TYPE_SDEI_NORMAL,
+ STACK_TYPE_SDEI_CRITICAL,
+};
+
+struct stack_info {
+ unsigned long low;
+ unsigned long high;
+ enum stack_type type;
+};
+
extern int unwind_frame(struct task_struct *tsk, struct stackframe *frame);
extern void walk_stackframe(struct task_struct *tsk, struct stackframe *frame,
int (*fn)(struct stackframe *, void *), void *data);
@@ -39,7 +54,8 @@ extern void dump_backtrace(struct pt_regs *regs, struct task_struct *tsk);

DECLARE_PER_CPU(unsigned long *, irq_stack_ptr);

-static inline bool on_irq_stack(unsigned long sp)
+static inline bool on_irq_stack(unsigned long sp,
+ struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);
unsigned long high = low + IRQ_STACK_SIZE;
@@ -47,46 +63,79 @@ static inline bool on_irq_stack(unsigned long sp)
if (!low)
return false;

- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = STACK_TYPE_IRQ;
+ }
+
+ return true;
}

-static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp)
+static inline bool on_task_stack(struct task_struct *tsk, unsigned long sp,
+ struct stack_info *info)
{
unsigned long low = (unsigned long)task_stack_page(tsk);
unsigned long high = low + THREAD_SIZE;

- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = STACK_TYPE_TASK;
+ }
+
+ return true;
}

#ifdef CONFIG_VMAP_STACK
DECLARE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)], overflow_stack);

-static inline bool on_overflow_stack(unsigned long sp)
+static inline bool on_overflow_stack(unsigned long sp,
+ struct stack_info *info)
{
unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);
unsigned long high = low + OVERFLOW_STACK_SIZE;

- return (low <= sp && sp < high);
+ if (sp < low || sp >= high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = STACK_TYPE_OVERFLOW;
+ }
+
+ return true;
}
#else
-static inline bool on_overflow_stack(unsigned long sp) { return false; }
+static inline bool on_overflow_stack(unsigned long sp,
+ struct stack_info *info) { return false; }
#endif

+
/*
* We can only safely access per-cpu stacks from current in a non-preemptible
* context.
*/
-static inline bool on_accessible_stack(struct task_struct *tsk, unsigned long sp)
+static inline bool on_accessible_stack(struct task_struct *tsk,
+ unsigned long sp,
+ struct stack_info *info)
{
- if (on_task_stack(tsk, sp))
+ if (on_task_stack(tsk, sp, info))
return true;
if (tsk != current || preemptible())
return false;
- if (on_irq_stack(sp))
+ if (on_irq_stack(sp, info))
return true;
- if (on_overflow_stack(sp))
+ if (on_overflow_stack(sp, info))
return true;
- if (on_sdei_stack(sp))
+ if (on_sdei_stack(sp, info))
return true;

return false;
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 5c338ce5a7fa..cf94e1498ba6 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -132,7 +132,7 @@ static bool regs_within_kernel_stack(struct pt_regs *regs, unsigned long addr)
{
return ((addr & ~(THREAD_SIZE - 1)) ==
(kernel_stack_pointer(regs) & ~(THREAD_SIZE - 1))) ||
- on_irq_stack(addr);
+ on_irq_stack(addr, NULL);
}

/**
diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
index 6b8d90d5ceae..7154fee1cb2b 100644
--- a/arch/arm64/kernel/sdei.c
+++ b/arch/arm64/kernel/sdei.c
@@ -88,23 +88,58 @@ static int init_sdei_stacks(void)
return err;
}

-bool _on_sdei_stack(unsigned long sp)
+bool on_sdei_normal_stack(unsigned long sp,
+ struct stack_info *info)
+{
+ unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
+ unsigned long high = low + SDEI_STACK_SIZE;
+
+ if (sp < low || sp >= high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = STACK_TYPE_SDEI_NORMAL;
+ }
+
+ return true;
+}
+
+bool on_sdei_critical_stack(unsigned long sp,
+ struct stack_info *info)
+{
+ unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);
+ unsigned long high = low + SDEI_STACK_SIZE;
+
+ if (sp < low || sp >= high)
+ return false;
+
+ if (info) {
+ info->low = low;
+ info->high = high;
+ info->type = STACK_TYPE_SDEI_CRITICAL;
+ }
+
+ return true;
+}
+
+bool _on_sdei_stack(unsigned long sp,
+ unsigned long *stack_low,
+ unsigned long *stack_high)
{
unsigned long low, high;

if (!IS_ENABLED(CONFIG_VMAP_STACK))
return false;

- low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);
- high = low + SDEI_STACK_SIZE;
-
- if (low <= sp && sp < high)
+ if (on_sdei_critical_stack(sp, info))
return true;

- low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
- high = low + SDEI_STACK_SIZE;
+ if (on_sdei_normal_stack(sp, info))
+ return true;

- return (low <= sp && sp < high);
+ return false;
}

unsigned long sdei_arch_get_entry_point(int conduit)
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index d5718a060672..4989f7ea1e59 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -50,7 +50,7 @@ int notrace unwind_frame(struct task_struct *tsk, struct stackframe *frame)
if (!tsk)
tsk = current;

- if (!on_accessible_stack(tsk, fp))
+ if (!on_accessible_stack(tsk, fp, NULL))
return -EINVAL;

frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
--
2.17.1
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