Commit d1f684e4 authored by Mark Rutland's avatar Mark Rutland Committed by Catalin Marinas
Browse files

arm64: stacktrace: rework stack boundary discovery 



In subsequent patches we'll want to acquire the stack boundaries
ahead-of-time, and we'll need to be able to acquire the relevant
stack_info regardless of whether we have an object the happens to be on
the stack.

This patch replaces the on_XXX_stack() helpers with stackinfo_get_XXX()
helpers, with the caller being responsible for the checking whether an
object is on a relevant stack. For the moment this is moved into the
on_accessible_stack() functions, making these slightly larger;
subsequent patches will remove the on_accessible_stack() functions and
simplify the logic.

The on_irq_stack() and on_task_stack() helpers are kept as these are
used by IRQ entry sequences and stackleak respectively. As they're only
used as predicates, the stack_info pointer parameter is removed in both
cases.

As the on_accessible_stack() functions are always passed a non-NULL info
pointer, these now update info unconditionally. When updating the type
to STACK_TYPE_UNKNOWN, the low/high bounds are also modified, but as
these will not be consumed this should have no adverse affect.

There should be no functional change as a result of this patch.

Signed-off-by: default avatarMark Rutland <mark.rutland@arm.com>
Reviewed-by: default avatarKalesh Singh <kaleshsingh@google.com>
Reviewed-by: default avatarMadhavan T. Venkataraman <madvenka@linux.microsoft.com>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Cc: Fuad Tabba <tabba@google.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20220901130646.1316937-7-mark.rutland@arm.com


Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 36f9a879

arch/arm64/include/asm/processor.h

+1 −1
Original line number Diff line number Diff line
@@ -410,7 +410,7 @@ long get_tagged_addr_ctrl(struct task_struct *task); 
 * The top of the current task's task stack

 */

#define current_top_of_stack()	((unsigned long)current->stack + THREAD_SIZE)

#define on_thread_stack()	(on_task_stack(current, current_stack_pointer, 1, NULL))

#define on_thread_stack()	(on_task_stack(current, current_stack_pointer, 1))



#endif /* __ASSEMBLY__ */

#endif /* __ASM_PROCESSOR_H */

arch/arm64/include/asm/stacktrace.h

+46 −32
Original line number Diff line number Diff line
@@ -22,77 +22,91 @@ 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, unsigned long size,

				struct stack_info *info)

static inline struct stack_info stackinfo_get_irq(void)

{

	unsigned long low = (unsigned long)raw_cpu_read(irq_stack_ptr);

	unsigned long high = low + IRQ_STACK_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_IRQ, info);

	return (struct stack_info) {

		.low = low,

		.high = high,

		.type = STACK_TYPE_IRQ,

	};

}



static inline bool on_task_stack(const struct task_struct *tsk,

				 unsigned long sp, unsigned long size,

				 struct stack_info *info)

static inline bool on_irq_stack(unsigned long sp, unsigned long size)

{

	struct stack_info info = stackinfo_get_irq();

	return stackinfo_on_stack(&info, sp, size);

}



static inline struct stack_info stackinfo_get_task(const struct task_struct *tsk)

{

	unsigned long low = (unsigned long)task_stack_page(tsk);

	unsigned long high = low + THREAD_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_TASK, info);

	return (struct stack_info) {

		.low = low,

		.high = high,

		.type = STACK_TYPE_TASK,

	};

}



static inline bool on_task_stack(const struct task_struct *tsk,

				 unsigned long sp, unsigned long size)

{

	struct stack_info info = stackinfo_get_task(tsk);

	return stackinfo_on_stack(&info, sp, size);

}



#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, unsigned long size,

				struct stack_info *info)

static inline struct stack_info stackinfo_get_overflow(void)

{

	unsigned long low = (unsigned long)raw_cpu_ptr(overflow_stack);

	unsigned long high = low + OVERFLOW_STACK_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_OVERFLOW, info);

	return (struct stack_info) {

		.low = low,

		.high = high,

		.type = STACK_TYPE_OVERFLOW,

	};

}

#else

static inline bool on_overflow_stack(unsigned long sp, unsigned long size,

				     struct stack_info *info)

{

	return false;

}

#define stackinfo_get_overflow()	stackinfo_get_unknown()

#endif



#if defined(CONFIG_ARM_SDE_INTERFACE) && defined(CONFIG_VMAP_STACK)

DECLARE_PER_CPU(unsigned long *, sdei_stack_normal_ptr);

DECLARE_PER_CPU(unsigned long *, sdei_stack_critical_ptr);



static inline bool on_sdei_normal_stack(unsigned long sp, unsigned long size,

					struct stack_info *info)

static inline struct stack_info stackinfo_get_sdei_normal(void)

{

	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);

	unsigned long high = low + SDEI_STACK_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_SDEI_NORMAL, info);

	return (struct stack_info) {

		.low = low,

		.high = high,

		.type = STACK_TYPE_SDEI_NORMAL,

	};

}



static inline bool on_sdei_critical_stack(unsigned long sp, unsigned long size,

					  struct stack_info *info)

static inline struct stack_info stackinfo_get_sdei_critical(void)

{

	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);

	unsigned long high = low + SDEI_STACK_SIZE;



	return on_stack(sp, size, low, high, STACK_TYPE_SDEI_CRITICAL, info);

	return (struct stack_info) {

		.low = low,

		.high = high,

		.type = STACK_TYPE_SDEI_CRITICAL,

	};

}

#else

static inline bool on_sdei_normal_stack(unsigned long sp, unsigned long size,

					struct stack_info *info)

{

	return false;

}



static inline bool on_sdei_critical_stack(unsigned long sp, unsigned long size,

					  struct stack_info *info)

{

	return false;

}

#define stackinfo_get_sdei_normal()	stackinfo_get_unknown()

#define stackinfo_get_sdei_critical()	stackinfo_get_unknown()

#endif



#endif	/* __ASM_STACKTRACE_H */

arch/arm64/include/asm/stacktrace/common.h

+9 −19
Original line number Diff line number Diff line
@@ -65,6 +65,15 @@ struct unwind_state { 
	struct task_struct *task;

};



static inline struct stack_info stackinfo_get_unknown(void)

{

	return (struct stack_info) {

		.low = 0,

		.high = 0,

		.type = STACK_TYPE_UNKNOWN,

	};

}



static inline bool stackinfo_on_stack(const struct stack_info *info,

				      unsigned long sp, unsigned long size)

{
@@ -77,25 +86,6 @@ static inline bool stackinfo_on_stack(const struct stack_info *info, 
	return true;

}



static inline bool on_stack(unsigned long sp, unsigned long size,

			    unsigned long low, unsigned long high,

			    enum stack_type type, struct stack_info *info)

{

	struct stack_info tmp = {

		.low = low,

		.high = high,

		.type = type,

	};



	if (!stackinfo_on_stack(&tmp, sp, size))

		return false;



	if (info)

		*info = tmp;



	return true;

}



static inline void unwind_init_common(struct unwind_state *state,

				      struct task_struct *task)

{

arch/arm64/kernel/ptrace.c

+1 −1
Original line number Diff line number Diff line
@@ -121,7 +121,7 @@ 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, sizeof(unsigned long), NULL);

		on_irq_stack(addr, sizeof(unsigned long));

}



/**

arch/arm64/kernel/stacktrace.c

+42 −23
Original line number Diff line number Diff line
@@ -67,36 +67,55 @@ static inline void unwind_init_from_task(struct unwind_state *state, 
	state->pc = thread_saved_pc(task);

}



/*

 * We can only safely access per-cpu stacks from current in a non-preemptible

 * context.

 */

static bool on_accessible_stack(const struct task_struct *tsk,

				unsigned long sp, unsigned long size,

				struct stack_info *info)

{

	if (info)

		info->type = STACK_TYPE_UNKNOWN;

	struct stack_info tmp;



	if (on_task_stack(tsk, sp, size, info))

		return true;

	tmp = stackinfo_get_task(tsk);

	if (stackinfo_on_stack(&tmp, sp, size))

		goto found;



	/*

	 * We can only safely access per-cpu stacks when unwinding the current

	 * task in a non-preemptible context.

	 */

	if (tsk != current || preemptible())

		return false;

	if (on_irq_stack(sp, size, info))

		return true;

	if (on_overflow_stack(sp, size, info))

		return true;

		goto not_found;



	if (IS_ENABLED(CONFIG_VMAP_STACK) &&

	    IS_ENABLED(CONFIG_ARM_SDE_INTERFACE) &&

	    in_nmi()) {

		if (on_sdei_critical_stack(sp, size, info))

			return true;

		if (on_sdei_normal_stack(sp, size, info))

			return true;

	}

	tmp = stackinfo_get_irq();

	if (stackinfo_on_stack(&tmp, sp, size))

		goto found;



	tmp = stackinfo_get_overflow();

	if (stackinfo_on_stack(&tmp, sp, size))

		goto found;



	/*

	 * We can only safely access SDEI stacks which unwinding the current

	 * task in an NMI context.

	 */

	if (!IS_ENABLED(CONFIG_VMAP_STACK) ||

	    !IS_ENABLED(CONFIG_ARM_SDE_INTERFACE) ||

	    !in_nmi())

		goto not_found;



	tmp = stackinfo_get_sdei_normal();

	if (stackinfo_on_stack(&tmp, sp, size))

		goto found;



	tmp = stackinfo_get_sdei_critical();

	if (stackinfo_on_stack(&tmp, sp, size))

		goto found;



not_found:

	*info = stackinfo_get_unknown();

	return false;



found:

	*info = tmp;

	return true;

}



/*