riscv: perf: Fix callchain parse error with kernel tracepoint events

commit 9a7e8ec0d4cc64870ea449b4fce5779b77496cbb upstream.

For RISC-V, when tracing with tracepoint events, the IP and status are
set to 0, preventing the perf code parsing the callchain and resolving
the symbols correctly.

 ./ply 'tracepoint:kmem/kmem_cache_alloc { @[stack]=count(); }'
 @:
 { <STACKID4294967282> }: 1

The fix is to implement perf_arch_fetch_caller_regs for riscv, which
fills several necessary registers used for callchain unwinding,
including epc, sp, s0 and status. It's similar to commit b3eac0265bf6
("arm: perf: Fix callchain parse error with kernel tracepoint events")
and commit 5b09a094f2fb ("arm64: perf: Fix callchain parse error with
kernel tracepoint events").

With this patch, callchain can be parsed correctly as:

 ./ply 'tracepoint:kmem/kmem_cache_alloc { @[stack]=count(); }'
 @:
 {
         __traceiter_kmem_cache_alloc+68
         __traceiter_kmem_cache_alloc+68
         kmem_cache_alloc+354
         __sigqueue_alloc+94
         __send_signal_locked+646
         send_signal_locked+154
         do_send_sig_info+84
         __kill_pgrp_info+130
         kill_pgrp+60
         isig+150
         n_tty_receive_signal_char+36
         n_tty_receive_buf_standard+2214
         n_tty_receive_buf_common+280
         n_tty_receive_buf2+26
         tty_ldisc_receive_buf+34
         tty_port_default_receive_buf+62
         flush_to_ldisc+158
         process_one_work+458
         worker_thread+138
         kthread+178
         riscv_cpufeature_patch_func+832
  }: 1

Signed-off-by: Ism Hong <ism.hong@gmail.com>
Link: https://lore.kernel.org/r/20230601095355.1168910-1-ism.hong@gmail.com
Fixes: 178e9fc47aae ("perf: riscv: preliminary RISC-V support")
Cc: stable@vger.kernel.org
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/riscv/include/asm/perf_event.h b/arch/riscv/include/asm/perf_event.h
index d42c901f9a9770985b53da11098d69cf7934cc62..665bbc9b2f840a5272eb493d799f21dab73dfd25 100644 (file)
--- a/arch/riscv/include/asm/perf_event.h
+++ b/arch/riscv/include/asm/perf_event.h
@@ -10,4 +10,11 @@
 
 #include <linux/perf_event.h>
 #define perf_arch_bpf_user_pt_regs(regs) (struct user_regs_struct *)regs
+
+#define perf_arch_fetch_caller_regs(regs, __ip) { \
+       (regs)->epc = (__ip); \
+       (regs)->s0 = (unsigned long) __builtin_frame_address(0); \
+       (regs)->sp = current_stack_pointer; \
+       (regs)->status = SR_PP; \
+}
 #endif /* _ASM_RISCV_PERF_EVENT_H */