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arm64: Add USER_STACKTRACE support

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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: chenqiwu <qiwu.chen@transsion.com>
Signed-off-by: chenqiwu <qiwu.chen@transsion.com>
Link: https://lore.kernel.org/r/20231219022229.10230-1-qiwu.chen@transsion.com
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
chenqiwu 2023-12-19 10:22:29 +08:00 committed by Will Deacon
parent 582c1aeee0
commit 410e471f87
3 changed files with 125 additions and 114 deletions
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1
arch/arm64/Kconfig
View File

@ -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.

118
arch/arm64/kernel/perf_callchain.c
View File

@ -10,95 +10,13 @@
#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)
static bool callchain_trace(void *data, unsigned long pc)
{
struct frame_tail buftail;
unsigned long err;
unsigned long lr;
struct perf_callchain_entry_ctx *entry = data;
/* 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;
return perf_callchain_store(entry, pc) == 0;
}
#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)
{
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;
return (struct compat_frame_tail __user *)compat_ptr(buftail.fp) - 1;
}
#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,

120
arch/arm64/kernel/stacktrace.c
View File

@ -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
}
}