Commit 410e471f authored by chenqiwu's avatar chenqiwu Committed by Will Deacon
Browse files

arm64: Add USER_STACKTRACE support 



Currently, userstacktrace is unsupported for ftrace and uprobe
tracers on arm64. This patch uses the perf_callchain_user() code
as blueprint to implement the arch_stack_walk_user() which add
userstacktrace support on arm64.
Meanwhile, we can use arch_stack_walk_user() to simplify the
implementation of perf_callchain_user().
This patch is tested pass with ftrace, uprobe and perf tracers
profiling userstacktrace cases.

Tested-by: default avatarchenqiwu <qiwu.chen@transsion.com>
Signed-off-by: default avatarchenqiwu <qiwu.chen@transsion.com>
Link: https://lore.kernel.org/r/20231219022229.10230-1-qiwu.chen@transsion.com


Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent 582c1aee

arch/arm64/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -258,6 +258,7 @@ config ARM64 
	select TRACE_IRQFLAGS_SUPPORT

	select TRACE_IRQFLAGS_NMI_SUPPORT

	select HAVE_SOFTIRQ_ON_OWN_STACK

	select USER_STACKTRACE_SUPPORT

	help

	  ARM 64-bit (AArch64) Linux support.

arch/arm64/kernel/perf_callchain.c

+4 −114
Original line number Diff line number Diff line
@@ -10,94 +10,12 @@ 


#include <asm/pointer_auth.h>



struct frame_tail {

	struct frame_tail	__user *fp;

	unsigned long		lr;

} __attribute__((packed));



/*

 * Get the return address for a single stackframe and return a pointer to the

 * next frame tail.

 */

static struct frame_tail __user *

user_backtrace(struct frame_tail __user *tail,

	       struct perf_callchain_entry_ctx *entry)

{

	struct frame_tail buftail;

	unsigned long err;

	unsigned long lr;



	/* Also check accessibility of one struct frame_tail beyond */

	if (!access_ok(tail, sizeof(buftail)))

		return NULL;



	pagefault_disable();

	err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));

	pagefault_enable();



	if (err)

		return NULL;



	lr = ptrauth_strip_user_insn_pac(buftail.lr);



	perf_callchain_store(entry, lr);



	/*

	 * Frame pointers should strictly progress back up the stack

	 * (towards higher addresses).

	 */

	if (tail >= buftail.fp)

		return NULL;



	return buftail.fp;

}



#ifdef CONFIG_COMPAT

/*

 * The registers we're interested in are at the end of the variable

 * length saved register structure. The fp points at the end of this

 * structure so the address of this struct is:

 * (struct compat_frame_tail *)(xxx->fp)-1

 *

 * This code has been adapted from the ARM OProfile support.

 */

struct compat_frame_tail {

	compat_uptr_t	fp; /* a (struct compat_frame_tail *) in compat mode */

	u32		sp;

	u32		lr;

} __attribute__((packed));



static struct compat_frame_tail __user *

compat_user_backtrace(struct compat_frame_tail __user *tail,

		      struct perf_callchain_entry_ctx *entry)

static bool callchain_trace(void *data, unsigned long pc)

{

	struct compat_frame_tail buftail;

	unsigned long err;



	/* Also check accessibility of one struct frame_tail beyond */

	if (!access_ok(tail, sizeof(buftail)))

		return NULL;



	pagefault_disable();

	err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));

	pagefault_enable();



	if (err)

		return NULL;



	perf_callchain_store(entry, buftail.lr);



	/*

	 * Frame pointers should strictly progress back up the stack

	 * (towards higher addresses).

	 */

	if (tail + 1 >= (struct compat_frame_tail __user *)

			compat_ptr(buftail.fp))

		return NULL;

	struct perf_callchain_entry_ctx *entry = data;



	return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;

	return perf_callchain_store(entry, pc) == 0;

}

#endif /* CONFIG_COMPAT */



void perf_callchain_user(struct perf_callchain_entry_ctx *entry,

			 struct pt_regs *regs)
@@ -107,35 +25,7 @@ void perf_callchain_user(struct perf_callchain_entry_ctx *entry, 
		return;

	}



	perf_callchain_store(entry, regs->pc);



	if (!compat_user_mode(regs)) {

		/* AARCH64 mode */

		struct frame_tail __user *tail;



		tail = (struct frame_tail __user *)regs->regs[29];



		while (entry->nr < entry->max_stack &&

		       tail && !((unsigned long)tail & 0x7))

			tail = user_backtrace(tail, entry);

	} else {

#ifdef CONFIG_COMPAT

		/* AARCH32 compat mode */

		struct compat_frame_tail __user *tail;



		tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;



		while ((entry->nr < entry->max_stack) &&

			tail && !((unsigned long)tail & 0x3))

			tail = compat_user_backtrace(tail, entry);

#endif

	}

}



static bool callchain_trace(void *data, unsigned long pc)

{

	struct perf_callchain_entry_ctx *entry = data;

	return perf_callchain_store(entry, pc) == 0;

	arch_stack_walk_user(callchain_trace, entry, regs);

}



void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,

arch/arm64/kernel/stacktrace.c

+120 −0
Original line number Diff line number Diff line
@@ -324,3 +324,123 @@ void show_stack(struct task_struct *tsk, unsigned long *sp, const char *loglvl) 
	dump_backtrace(NULL, tsk, loglvl);

	barrier();

}



/*

 * The struct defined for userspace stack frame in AARCH64 mode.

 */

struct frame_tail {

	struct frame_tail	__user *fp;

	unsigned long		lr;

} __attribute__((packed));



/*

 * Get the return address for a single stackframe and return a pointer to the

 * next frame tail.

 */

static struct frame_tail __user *

unwind_user_frame(struct frame_tail __user *tail, void *cookie,

	       stack_trace_consume_fn consume_entry)

{

	struct frame_tail buftail;

	unsigned long err;

	unsigned long lr;



	/* Also check accessibility of one struct frame_tail beyond */

	if (!access_ok(tail, sizeof(buftail)))

		return NULL;



	pagefault_disable();

	err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));

	pagefault_enable();



	if (err)

		return NULL;



	lr = ptrauth_strip_user_insn_pac(buftail.lr);



	if (!consume_entry(cookie, lr))

		return NULL;



	/*

	 * Frame pointers should strictly progress back up the stack

	 * (towards higher addresses).

	 */

	if (tail >= buftail.fp)

		return NULL;



	return buftail.fp;

}



#ifdef CONFIG_COMPAT

/*

 * The registers we're interested in are at the end of the variable

 * length saved register structure. The fp points at the end of this

 * structure so the address of this struct is:

 * (struct compat_frame_tail *)(xxx->fp)-1

 *

 * This code has been adapted from the ARM OProfile support.

 */

struct compat_frame_tail {

	compat_uptr_t	fp; /* a (struct compat_frame_tail *) in compat mode */

	u32		sp;

	u32		lr;

} __attribute__((packed));



static struct compat_frame_tail __user *

unwind_compat_user_frame(struct compat_frame_tail __user *tail, void *cookie,

				stack_trace_consume_fn consume_entry)

{

	struct compat_frame_tail buftail;

	unsigned long err;



	/* Also check accessibility of one struct frame_tail beyond */

	if (!access_ok(tail, sizeof(buftail)))

		return NULL;



	pagefault_disable();

	err = __copy_from_user_inatomic(&buftail, tail, sizeof(buftail));

	pagefault_enable();



	if (err)

		return NULL;



	if (!consume_entry(cookie, buftail.lr))

		return NULL;



	/*

	 * Frame pointers should strictly progress back up the stack

	 * (towards higher addresses).

	 */

	if (tail + 1 >= (struct compat_frame_tail __user *)

			compat_ptr(buftail.fp))

		return NULL;



	return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;

}

#endif /* CONFIG_COMPAT */





void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,

					const struct pt_regs *regs)

{

	if (!consume_entry(cookie, regs->pc))

		return;



	if (!compat_user_mode(regs)) {

		/* AARCH64 mode */

		struct frame_tail __user *tail;



		tail = (struct frame_tail __user *)regs->regs[29];

		while (tail && !((unsigned long)tail & 0x7))

			tail = unwind_user_frame(tail, cookie, consume_entry);

	} else {

#ifdef CONFIG_COMPAT

		/* AARCH32 compat mode */

		struct compat_frame_tail __user *tail;



		tail = (struct compat_frame_tail __user *)regs->compat_fp - 1;

		while (tail && !((unsigned long)tail & 0x3))

			tail = unwind_compat_user_frame(tail, cookie, consume_entry);

#endif

	}

}