From: Jinjie Ruan Date: Mon, 8 Jul 2024 03:28:47 +0000 (+0800) Subject: riscv: stacktrace: Add USER_STACKTRACE support X-Git-Tag: v6.12-rc1~76^2~19^2 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=1a7483318274d0ec60f160e604c2a1dbce27fc0a;p=thirdparty%2Fkernel%2Flinux.git 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: => /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 Tested-by: Jinjie Ruan Cc: Björn Töpel Link: https://lore.kernel.org/r/20240708032847.2998158-3-ruanjinjie@huawei.com Signed-off-by: Palmer Dabbelt --- diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 0f3cd7c3a4360..443bac99c94a8 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -200,6 +200,7 @@ 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 2932791e93882..c7468af77c663 100644 --- a/arch/riscv/kernel/perf_callchain.c +++ b/arch/riscv/kernel/perf_callchain.c @@ -6,37 +6,9 @@ #include -/* - * 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 c6d5de22463f9..153a2db4c5fa1 100644 --- a/arch/riscv/kernel/stacktrace.c +++ b/arch/riscv/kernel/stacktrace.c @@ -162,3 +162,46 @@ 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); +}