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Message-ID: <20240708032847.2998158-3-ruanjinjie@huawei.com>
Date: Mon, 8 Jul 2024 11:28:47 +0800
From: Jinjie Ruan <ruanjinjie@...wei.com>
To: <bjorn@...nel.org>, <paul.walmsley@...ive.com>, <palmer@...belt.com>,
<aou@...s.berkeley.edu>, <peterz@...radead.org>, <mingo@...hat.com>,
<acme@...nel.org>, <namhyung@...nel.org>, <mark.rutland@....com>,
<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
<irogers@...gle.com>, <adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
<dev.mbstr@...il.com>, <samuel.holland@...ive.com>,
<linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
<linux-perf-users@...r.kernel.org>
CC: <ruanjinjie@...wei.com>
Subject: [PATCH v3 2/2] riscv: stacktrace: Add USER_STACKTRACE support
Currently, userstacktrace is unsupported for riscv. So use the
perf_callchain_user() code as blueprint to implement the
arch_stack_walk_user() which add userstacktrace support on riscv.
Meanwhile, we can use arch_stack_walk_user() to simplify the implementation
of perf_callchain_user().
A ftrace test case is shown as below:
# cd /sys/kernel/debug/tracing
# echo 1 > options/userstacktrace
# echo 1 > options/sym-userobj
# echo 1 > events/sched/sched_process_fork/enable
# cat trace
......
bash-178 [000] ...1. 97.968395: sched_process_fork: comm=bash pid=178 child_comm=bash child_pid=231
bash-178 [000] ...1. 97.970075: <user stack trace>
=> /lib/libc.so.6[+0xb5090]
Also a simple perf test is ok as below:
# perf record -e cpu-clock --call-graph fp top
# perf report --call-graph
.....
[[31m 66.54%[[m 0.00% top [kernel.kallsyms] [k] ret_from_exception
|
---ret_from_exception
|
|--[[31m58.97%[[m--do_trap_ecall_u
| |
| |--[[31m17.34%[[m--__riscv_sys_read
| | ksys_read
| | |
| | --[[31m16.88%[[m--vfs_read
| | |
| | |--[[31m10.90%[[m--seq_read
Signed-off-by: Jinjie Ruan <ruanjinjie@...wei.com>
Tested-by: Jinjie Ruan <ruanjinjie@...wei.com>
Cc: Björn Töpel <bjorn@...nel.org>
---
v3:
- Remove the LTP message as Björn suggested.
- Keep fp 16-bytes aligned in arch_stack_walk_user().
- Add the test info.
v2:
- Fix the cocci warning, !A || A && B is equivalent to !A || B.
---
---
arch/riscv/Kconfig | 1 +
arch/riscv/kernel/perf_callchain.c | 46 ++----------------------------
arch/riscv/kernel/stacktrace.c | 43 ++++++++++++++++++++++++++++
3 files changed, 47 insertions(+), 43 deletions(-)
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 3b44e7b51436..46121dbcf750 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -194,6 +194,7 @@ config RISCV
select THREAD_INFO_IN_TASK
select TRACE_IRQFLAGS_SUPPORT
select UACCESS_MEMCPY if !MMU
+ select USER_STACKTRACE_SUPPORT
select ZONE_DMA32 if 64BIT
config CLANG_SUPPORTS_DYNAMIC_FTRACE
diff --git a/arch/riscv/kernel/perf_callchain.c b/arch/riscv/kernel/perf_callchain.c
index 2932791e9388..c7468af77c66 100644
--- a/arch/riscv/kernel/perf_callchain.c
+++ b/arch/riscv/kernel/perf_callchain.c
@@ -6,37 +6,9 @@
#include <asm/stacktrace.h>
-/*
- * Get the return address for a single stackframe and return a pointer to the
- * next frame tail.
- */
-static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
- unsigned long fp, unsigned long reg_ra)
+static bool fill_callchain(void *entry, unsigned long pc)
{
- struct stackframe buftail;
- unsigned long ra = 0;
- unsigned long __user *user_frame_tail =
- (unsigned long __user *)(fp - sizeof(struct stackframe));
-
- /* Check accessibility of one struct frame_tail beyond */
- if (!access_ok(user_frame_tail, sizeof(buftail)))
- return 0;
- if (__copy_from_user_inatomic(&buftail, user_frame_tail,
- sizeof(buftail)))
- return 0;
-
- if (reg_ra != 0)
- ra = reg_ra;
- else
- ra = buftail.ra;
-
- fp = buftail.fp;
- if (ra != 0)
- perf_callchain_store(entry, ra);
- else
- return 0;
-
- return fp;
+ return perf_callchain_store(entry, pc) == 0;
}
/*
@@ -56,19 +28,7 @@ static unsigned long user_backtrace(struct perf_callchain_entry_ctx *entry,
void perf_callchain_user(struct perf_callchain_entry_ctx *entry,
struct pt_regs *regs)
{
- unsigned long fp = 0;
-
- fp = regs->s0;
- perf_callchain_store(entry, regs->epc);
-
- fp = user_backtrace(entry, fp, regs->ra);
- while (fp && !(fp & 0x7) && entry->nr < entry->max_stack)
- fp = user_backtrace(entry, fp, 0);
-}
-
-static bool fill_callchain(void *entry, unsigned long pc)
-{
- return perf_callchain_store(entry, pc) == 0;
+ arch_stack_walk_user(fill_callchain, entry, regs);
}
void perf_callchain_kernel(struct perf_callchain_entry_ctx *entry,
diff --git a/arch/riscv/kernel/stacktrace.c b/arch/riscv/kernel/stacktrace.c
index 0d3f00eb0bae..5480cc11b523 100644
--- a/arch/riscv/kernel/stacktrace.c
+++ b/arch/riscv/kernel/stacktrace.c
@@ -161,3 +161,46 @@ noinline noinstr void arch_stack_walk(stack_trace_consume_fn consume_entry, void
{
walk_stackframe(task, regs, consume_entry, cookie);
}
+
+/*
+ * Get the return address for a single stackframe and return a pointer to the
+ * next frame tail.
+ */
+static unsigned long unwind_user_frame(stack_trace_consume_fn consume_entry,
+ void *cookie, unsigned long fp,
+ unsigned long reg_ra)
+{
+ struct stackframe buftail;
+ unsigned long ra = 0;
+ unsigned long __user *user_frame_tail =
+ (unsigned long __user *)(fp - sizeof(struct stackframe));
+
+ /* Check accessibility of one struct frame_tail beyond */
+ if (!access_ok(user_frame_tail, sizeof(buftail)))
+ return 0;
+ if (__copy_from_user_inatomic(&buftail, user_frame_tail,
+ sizeof(buftail)))
+ return 0;
+
+ ra = reg_ra ? : buftail.ra;
+
+ fp = buftail.fp;
+ if (!ra || !consume_entry(cookie, ra))
+ return 0;
+
+ return fp;
+}
+
+void arch_stack_walk_user(stack_trace_consume_fn consume_entry, void *cookie,
+ const struct pt_regs *regs)
+{
+ unsigned long fp = 0;
+
+ fp = regs->s0;
+ if (!consume_entry(cookie, regs->epc))
+ return;
+
+ fp = unwind_user_frame(consume_entry, cookie, fp, regs->ra);
+ while (fp && !(fp & 0x7))
+ fp = unwind_user_frame(consume_entry, cookie, fp, 0);
+}
--
2.34.1
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