[PATCH V4 2/3] riscv: Add support for perf registers sampling

Mao Han
2019-08-20T08:57:36Z

This patch implements the perf registers sampling and validation API
for riscv arch. The valid registers and their register ID are defined in
perf_regs.h. Perf tool can backtrace in userspace with unwind library
and the registers/user stack dump support.

Signed-off-by: Mao Han <han_mao@c-sky.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Palmer Dabbelt <palmer@sifive.com>
Cc: linux-riscv <linux-riscv@lists.infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Guo Ren <guoren@kernel.org>
---
arch/riscv/Kconfig | 2 ++
arch/riscv/include/uapi/asm/perf_regs.h | 42 +++++++++++++++++++++++++++++++
arch/riscv/kernel/Makefile | 1 +
arch/riscv/kernel/perf_regs.c | 44 +++++++++++++++++++++++++++++++++
4 files changed, 89 insertions(+)
create mode 100644 arch/riscv/include/uapi/asm/perf_regs.h
create mode 100644 arch/riscv/kernel/perf_regs.c

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 59a4727..4bc976d 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -35,6 +35,8 @@ config RISCV
select HAVE_DMA_CONTIGUOUS
select HAVE_FUTEX_CMPXCHG if FUTEX
select HAVE_PERF_EVENTS
+ select HAVE_PERF_REGS
+ select HAVE_PERF_USER_STACK_DUMP
select HAVE_SYSCALL_TRACEPOINTS
select IRQ_DOMAIN
select SPARSE_IRQ
diff --git a/arch/riscv/include/uapi/asm/perf_regs.h b/arch/riscv/include/uapi/asm/perf_regs.h
new file mode 100644
index 0000000..df1a581
--- /dev/null
+++ b/arch/riscv/include/uapi/asm/perf_regs.h
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#ifndef _ASM_RISCV_PERF_REGS_H
+#define _ASM_RISCV_PERF_REGS_H
+
+enum perf_event_riscv_regs {
+ PERF_REG_RISCV_PC,
+ PERF_REG_RISCV_RA,
+ PERF_REG_RISCV_SP,
+ PERF_REG_RISCV_GP,
+ PERF_REG_RISCV_TP,
+ PERF_REG_RISCV_T0,
+ PERF_REG_RISCV_T1,
+ PERF_REG_RISCV_T2,
+ PERF_REG_RISCV_S0,
+ PERF_REG_RISCV_S1,
+ PERF_REG_RISCV_A0,
+ PERF_REG_RISCV_A1,
+ PERF_REG_RISCV_A2,
+ PERF_REG_RISCV_A3,
+ PERF_REG_RISCV_A4,
+ PERF_REG_RISCV_A5,
+ PERF_REG_RISCV_A6,
+ PERF_REG_RISCV_A7,
+ PERF_REG_RISCV_S2,
+ PERF_REG_RISCV_S3,
+ PERF_REG_RISCV_S4,
+ PERF_REG_RISCV_S5,
+ PERF_REG_RISCV_S6,
+ PERF_REG_RISCV_S7,
+ PERF_REG_RISCV_S8,
+ PERF_REG_RISCV_S9,
+ PERF_REG_RISCV_S10,
+ PERF_REG_RISCV_S11,
+ PERF_REG_RISCV_T3,
+ PERF_REG_RISCV_T4,
+ PERF_REG_RISCV_T5,
+ PERF_REG_RISCV_T6,
+ PERF_REG_RISCV_MAX,
+};
+#endif /* _ASM_RISCV_PERF_REGS_H */
diff --git a/arch/riscv/kernel/Makefile b/arch/riscv/kernel/Makefile
index b1bea89..696020f 100644
--- a/arch/riscv/kernel/Makefile
+++ b/arch/riscv/kernel/Makefile
@@ -40,5 +40,6 @@ obj-$(CONFIG_DYNAMIC_FTRACE) += mcount-dyn.o

obj-$(CONFIG_PERF_EVENTS) += perf_event.o
obj-$(CONFIG_PERF_EVENTS) += perf_callchain.o
+obj-$(CONFIG_HAVE_PERF_REGS) += perf_regs.o

clean:
diff --git a/arch/riscv/kernel/perf_regs.c b/arch/riscv/kernel/perf_regs.c
new file mode 100644
index 0000000..04a38fb
--- /dev/null
+++ b/arch/riscv/kernel/perf_regs.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2019 Hangzhou C-SKY Microsystems co.,ltd. */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/perf_event.h>
+#include <linux/bug.h>
+#include <asm/perf_regs.h>
+#include <asm/ptrace.h>
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+ if (WARN_ON_ONCE((u32)idx >= PERF_REG_RISCV_MAX))
+ return 0;
+
+ return ((unsigned long *)regs)[idx];
+}
+
+#define REG_RESERVED (~((1ULL << PERF_REG_RISCV_MAX) - 1))
+
+int perf_reg_validate(u64 mask)
+{
+ if (!mask || mask & REG_RESERVED)
+ return -EINVAL;
+
+ return 0;
+}
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+#if __riscv_xlen == 64
+ return PERF_SAMPLE_REGS_ABI_64;
+#else
+ return PERF_SAMPLE_REGS_ABI_32;
+#endif
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+ struct pt_regs *regs,
+ struct pt_regs *regs_user_copy)
+{
+ regs_user->regs = task_pt_regs(current);
+ regs_user->abi = perf_reg_abi(current);
+}
--
2.7.4