Commit be63c647 authored by Kalesh Singh's avatar Kalesh Singh Committed by Marc Zyngier
Browse files

arm64: stacktrace: Factor out unwind_next_common() 



Move common unwind_next logic to stacktrace/common.h. This allows
reusing the code in the implementation the nVHE hypervisor stack
unwinder, later in this series.

Signed-off-by: default avatarKalesh Singh <kaleshsingh@google.com>
Reviewed-by: default avatarFuad Tabba <tabba@google.com>
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Tested-by: default avatarFuad Tabba <tabba@google.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20220726073750.3219117-4-kaleshsingh@google.com
parent 15a59f19

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

+50 −0
Original line number Diff line number Diff line
@@ -65,6 +65,10 @@ struct unwind_state { 
static inline bool on_overflow_stack(unsigned long sp, unsigned long size,

				     struct stack_info *info);



static inline bool on_accessible_stack(const struct task_struct *tsk,

				       unsigned long sp, unsigned long size,

				       struct stack_info *info);



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)
@@ -120,4 +124,50 @@ static inline void unwind_init_common(struct unwind_state *state, 
	state->prev_type = STACK_TYPE_UNKNOWN;

}



static inline int unwind_next_common(struct unwind_state *state,

				     struct stack_info *info)

{

	struct task_struct *tsk = state->task;

	unsigned long fp = state->fp;



	if (fp & 0x7)

		return -EINVAL;



	if (!on_accessible_stack(tsk, fp, 16, info))

		return -EINVAL;



	if (test_bit(info->type, state->stacks_done))

		return -EINVAL;



	/*

	 * As stacks grow downward, any valid record on the same stack must be

	 * at a strictly higher address than the prior record.

	 *

	 * Stacks can nest in several valid orders, e.g.

	 *

	 * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL

	 * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW

	 *

	 * ... but the nesting itself is strict. Once we transition from one

	 * stack to another, it's never valid to unwind back to that first

	 * stack.

	 */

	if (info->type == state->prev_type) {

		if (fp <= state->prev_fp)

			return -EINVAL;

	} else {

		__set_bit(state->prev_type, state->stacks_done);

	}



	/*

	 * Record this frame record's values and location. The prev_fp and

	 * prev_type are only meaningful to the next unwind_next() invocation.

	 */

	state->fp = READ_ONCE(*(unsigned long *)(fp));

	state->pc = READ_ONCE(*(unsigned long *)(fp + 8));

	state->prev_fp = fp;

	state->prev_type = info->type;



	return 0;

}

#endif	/* __ASM_STACKTRACE_COMMON_H */

arch/arm64/kernel/stacktrace.c

+4 −37
Original line number Diff line number Diff line
@@ -81,48 +81,15 @@ static int notrace unwind_next(struct unwind_state *state) 
	struct task_struct *tsk = state->task;

	unsigned long fp = state->fp;

	struct stack_info info;

	int err;



	/* Final frame; nothing to unwind */

	if (fp == (unsigned long)task_pt_regs(tsk)->stackframe)

		return -ENOENT;



	if (fp & 0x7)

		return -EINVAL;



	if (!on_accessible_stack(tsk, fp, 16, &info))

		return -EINVAL;



	if (test_bit(info.type, state->stacks_done))

		return -EINVAL;



	/*

	 * As stacks grow downward, any valid record on the same stack must be

	 * at a strictly higher address than the prior record.

	 *

	 * Stacks can nest in several valid orders, e.g.

	 *

	 * TASK -> IRQ -> OVERFLOW -> SDEI_NORMAL

	 * TASK -> SDEI_NORMAL -> SDEI_CRITICAL -> OVERFLOW

	 *

	 * ... but the nesting itself is strict. Once we transition from one

	 * stack to another, it's never valid to unwind back to that first

	 * stack.

	 */

	if (info.type == state->prev_type) {

		if (fp <= state->prev_fp)

			return -EINVAL;

	} else {

		__set_bit(state->prev_type, state->stacks_done);

	}



	/*

	 * Record this frame record's values and location. The prev_fp and

	 * prev_type are only meaningful to the next unwind_next() invocation.

	 */

	state->fp = READ_ONCE(*(unsigned long *)(fp));

	state->pc = READ_ONCE(*(unsigned long *)(fp + 8));

	state->prev_fp = fp;

	state->prev_type = info.type;

	err = unwind_next_common(state, &info);

	if (err)

		return err;



	state->pc = ptrauth_strip_insn_pac(state->pc);