MIPS: kernel: Support extracting off-line stack traces from user-space with perf

Add perf_event_mips_regs/perf_reg_value/perf_reg_validate to support
features HAVE_PERF_REGS/HAVE_PERF_USER_STACK_DUMP in kernel.

[ayan@wavecomp.com: Repick this patch for unwinding userstack backtrace
 by perf and libunwind on MIPS based CPU.]

[ralf@linux-mips.org: Add perf_get_regs_user() which is required after
'commit 88a7c26af8da ("perf: Move task_pt_regs sampling into arch code")'.]

[yangtiezhu@loongson.cn: Fix build error about perf_get_regs_user() after
commit 76a4efa80900 ("perf/arch: Remove perf_sample_data::regs_user_copy"),
and also separate the original patches into two parts (MIPS kernel and perf
tools) to merge easily.]

The original patches:
https://lore.kernel.org/patchwork/patch/1126521/
https://lore.kernel.org/patchwork/patch/1126520/

Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Archer Yan <ayan@wavecomp.com>
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 71df230..57b0679 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -77,6 +77,8 @@ config MIPS
        select HAVE_NMI
        select HAVE_OPROFILE
        select HAVE_PERF_EVENTS
+       select HAVE_PERF_REGS
+       select HAVE_PERF_USER_STACK_DUMP
        select HAVE_REGS_AND_STACK_ACCESS_API
        select HAVE_RSEQ
        select HAVE_SPARSE_SYSCALL_NR

diff --git a/arch/mips/include/uapi/asm/perf_regs.h b/arch/mips/include/uapi/asm/perf_regs.h
new file mode 100644 (file)
index 0000000..d0f4ecd
--- /dev/null
+++ b/arch/mips/include/uapi/asm/perf_regs.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _ASM_MIPS_PERF_REGS_H
+#define _ASM_MIPS_PERF_REGS_H
+
+enum perf_event_mips_regs {
+       PERF_REG_MIPS_PC,
+       PERF_REG_MIPS_R1,
+       PERF_REG_MIPS_R2,
+       PERF_REG_MIPS_R3,
+       PERF_REG_MIPS_R4,
+       PERF_REG_MIPS_R5,
+       PERF_REG_MIPS_R6,
+       PERF_REG_MIPS_R7,
+       PERF_REG_MIPS_R8,
+       PERF_REG_MIPS_R9,
+       PERF_REG_MIPS_R10,
+       PERF_REG_MIPS_R11,
+       PERF_REG_MIPS_R12,
+       PERF_REG_MIPS_R13,
+       PERF_REG_MIPS_R14,
+       PERF_REG_MIPS_R15,
+       PERF_REG_MIPS_R16,
+       PERF_REG_MIPS_R17,
+       PERF_REG_MIPS_R18,
+       PERF_REG_MIPS_R19,
+       PERF_REG_MIPS_R20,
+       PERF_REG_MIPS_R21,
+       PERF_REG_MIPS_R22,
+       PERF_REG_MIPS_R23,
+       PERF_REG_MIPS_R24,
+       PERF_REG_MIPS_R25,
+       PERF_REG_MIPS_R26,
+       PERF_REG_MIPS_R27,
+       PERF_REG_MIPS_R28,
+       PERF_REG_MIPS_R29,
+       PERF_REG_MIPS_R30,
+       PERF_REG_MIPS_R31,
+       PERF_REG_MIPS_MAX = PERF_REG_MIPS_R31 + 1,
+};
+#endif /* _ASM_MIPS_PERF_REGS_H */

diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 2303a58..a893ea0 100644 (file)
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -103,7 +103,7 @@ obj-$(CONFIG_MIPSR2_TO_R6_EMULATOR) += mips-r2-to-r6-emul.o
 
 CFLAGS_cpu-bugs64.o    = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/null -x c /dev/null >/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
 
-obj-$(CONFIG_PERF_EVENTS)      += perf_event.o
+obj-$(CONFIG_PERF_EVENTS)      += perf_event.o perf_regs.o
 obj-$(CONFIG_HW_PERF_EVENTS)   += perf_event_mipsxx.o
 
 obj-$(CONFIG_JUMP_LABEL)       += jump_label.o

diff --git a/arch/mips/kernel/perf_regs.c b/arch/mips/kernel/perf_regs.c
new file mode 100644 (file)
index 0000000..e686780
--- /dev/null
+++ b/arch/mips/kernel/perf_regs.c
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Some parts derived from x86 version of this file.
+ *
+ * Copyright (C) 2013 Cavium, Inc.
+ */
+
+#include <linux/perf_event.h>
+
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_32BIT
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+       return PERF_SAMPLE_REGS_ABI_32;
+}
+#else /* Must be CONFIG_64BIT */
+u64 perf_reg_abi(struct task_struct *tsk)
+{
+       if (test_tsk_thread_flag(tsk, TIF_32BIT_REGS))
+               return PERF_SAMPLE_REGS_ABI_32;
+       else
+               return PERF_SAMPLE_REGS_ABI_64;
+}
+#endif /* CONFIG_32BIT */
+
+int perf_reg_validate(u64 mask)
+{
+       if (!mask)
+               return -EINVAL;
+       if (mask & ~((1ull << PERF_REG_MIPS_MAX) - 1))
+               return -EINVAL;
+       return 0;
+}
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+       long v;
+
+       switch (idx) {
+       case PERF_REG_MIPS_PC:
+               v = regs->cp0_epc;
+               break;
+       case PERF_REG_MIPS_R1 ... PERF_REG_MIPS_R25:
+               v = regs->regs[idx - PERF_REG_MIPS_R1 + 1];
+               break;
+       case PERF_REG_MIPS_R28 ... PERF_REG_MIPS_R31:
+               v = regs->regs[idx - PERF_REG_MIPS_R28 + 28];
+               break;
+
+       default:
+               WARN_ON_ONCE(1);
+               return 0;
+       }
+
+       return (s64)v; /* Sign extend if 32-bit. */
+}
+
+void perf_get_regs_user(struct perf_regs *regs_user,
+                       struct pt_regs *regs)
+{
+       regs_user->regs = task_pt_regs(current);
+       regs_user->abi = perf_reg_abi(current);
+}