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: 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>

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 7b11c98b3e84bf76bcd6a33b34af257a9b7f48d7..7f7bbee7d257332fa0d20ed509f4c3fb19a94457 100644 (file)
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -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.
 

diff --git a/arch/arm64/kernel/perf_callchain.c b/arch/arm64/kernel/perf_callchain.c
index 6d157f32187b73eb2935f647732cd19c4a758754..e8ed5673f48174bdd28799dfb39cec00606d0b5e 100644 (file)
--- a/arch/arm64/kernel/perf_callchain.c
+++ b/arch/arm64/kernel/perf_callchain.c
@@ -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,

diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index 684c26511696bbb264d9e2b988b8ed93f14a8e58..6b32588603778da3662a99f5d71b934ab44278b4 100644 (file)
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -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
+       }
+}