[PATCH 1/7] perf: Unified API to record selective sets of arch registers

From: Jiri Olsa
Date: Fri Jul 27 2012 - 08:24:19 EST

This brings a new API to help the selective dump of registers on
event sampling, and its implementation for x86 arch.

Added HAVE_PERF_REGS config option to determine if the architecture
provides perf registers ABI.

The information about desired registers will be passed in u64 mask.
It's up to the architecture to map the registers into the mask bits.

For the x86 arch implementation, both 32 and 64 bit registers
bits are defined within single enum to ensure 64 bit system can
provide register dump for compat task if needed in the future.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Original-patch-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
arch/Kconfig | 6 +++
arch/x86/Kconfig | 1 +
arch/x86/include/asm/perf_regs.h | 33 ++++++++++++++
arch/x86/kernel/Makefile | 2 +
arch/x86/kernel/perf_regs.c | 90 ++++++++++++++++++++++++++++++++++++++
include/linux/perf_regs.h | 19 ++++++++
6 files changed, 151 insertions(+), 0 deletions(-)
create mode 100644 arch/x86/include/asm/perf_regs.h
create mode 100644 arch/x86/kernel/perf_regs.c
create mode 100644 include/linux/perf_regs.h

diff --git a/arch/Kconfig b/arch/Kconfig
index 8c3d957..32f4873 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -222,6 +222,12 @@ config HAVE_PERF_EVENTS_NMI
subsystem. Also has support for calculating CPU cycle events
to determine how many clock cycles in a given period.

+config HAVE_PERF_REGS
+ bool
+ help
+ Support selective register dumps for perf events. This includes
+ bit-mapping of each registers and a unique architecture id.
+
config HAVE_ARCH_JUMP_LABEL
bool

diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 94de2c5..acebbd6 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -60,6 +60,7 @@ config X86
select HAVE_MIXED_BREAKPOINTS_REGS
select PERF_EVENTS
select HAVE_PERF_EVENTS_NMI
+ select HAVE_PERF_REGS
select ANON_INODES
select HAVE_ALIGNED_STRUCT_PAGE if SLUB && !M386
select HAVE_CMPXCHG_LOCAL if !M386
diff --git a/arch/x86/include/asm/perf_regs.h b/arch/x86/include/asm/perf_regs.h
new file mode 100644
index 0000000..3f2207b
--- /dev/null
+++ b/arch/x86/include/asm/perf_regs.h
@@ -0,0 +1,33 @@
+#ifndef _ASM_X86_PERF_REGS_H
+#define _ASM_X86_PERF_REGS_H
+
+enum perf_event_x86_regs {
+ PERF_REG_X86_AX,
+ PERF_REG_X86_BX,
+ PERF_REG_X86_CX,
+ PERF_REG_X86_DX,
+ PERF_REG_X86_SI,
+ PERF_REG_X86_DI,
+ PERF_REG_X86_BP,
+ PERF_REG_X86_SP,
+ PERF_REG_X86_IP,
+ PERF_REG_X86_FLAGS,
+ PERF_REG_X86_CS,
+ PERF_REG_X86_SS,
+ PERF_REG_X86_DS,
+ PERF_REG_X86_ES,
+ PERF_REG_X86_FS,
+ PERF_REG_X86_GS,
+ PERF_REG_X86_R8,
+ PERF_REG_X86_R9,
+ PERF_REG_X86_R10,
+ PERF_REG_X86_R11,
+ PERF_REG_X86_R12,
+ PERF_REG_X86_R13,
+ PERF_REG_X86_R14,
+ PERF_REG_X86_R15,
+
+ PERF_REG_X86_32_MAX = PERF_REG_X86_GS + 1,
+ PERF_REG_X86_64_MAX = PERF_REG_X86_R15 + 1,
+};
+#endif /* _ASM_X86_PERF_REGS_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8215e56..8d7a619 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -100,6 +100,8 @@ obj-$(CONFIG_SWIOTLB) += pci-swiotlb.o
obj-$(CONFIG_OF) += devicetree.o
obj-$(CONFIG_UPROBES) += uprobes.o

+obj-$(CONFIG_PERF_EVENTS) += perf_regs.o
+
###
# 64 bit specific files
ifeq ($(CONFIG_X86_64),y)
diff --git a/arch/x86/kernel/perf_regs.c b/arch/x86/kernel/perf_regs.c
new file mode 100644
index 0000000..c00c92a
--- /dev/null
+++ b/arch/x86/kernel/perf_regs.c
@@ -0,0 +1,90 @@
+
+#include <linux/kernel.h>
+#include <linux/bug.h>
+#include <linux/stddef.h>
+#include <asm/perf_regs.h>
+#include <asm/ptrace.h>
+
+#ifdef CONFIG_X86_32
+#define PERF_REG_X86_MAX PERF_REG_X86_32_MAX
+#else
+#define PERF_REG_X86_MAX PERF_REG_X86_64_MAX
+#endif
+
+#define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
+
+static unsigned int pt_regs_offset[PERF_REG_X86_MAX] = {
+ PT_REGS_OFFSET(PERF_REG_X86_AX, ax),
+ PT_REGS_OFFSET(PERF_REG_X86_BX, bx),
+ PT_REGS_OFFSET(PERF_REG_X86_CX, cx),
+ PT_REGS_OFFSET(PERF_REG_X86_DX, dx),
+ PT_REGS_OFFSET(PERF_REG_X86_SI, si),
+ PT_REGS_OFFSET(PERF_REG_X86_DI, di),
+ PT_REGS_OFFSET(PERF_REG_X86_BP, bp),
+ PT_REGS_OFFSET(PERF_REG_X86_SP, sp),
+ PT_REGS_OFFSET(PERF_REG_X86_IP, ip),
+ PT_REGS_OFFSET(PERF_REG_X86_FLAGS, flags),
+ PT_REGS_OFFSET(PERF_REG_X86_CS, cs),
+ PT_REGS_OFFSET(PERF_REG_X86_SS, ss),
+#ifdef CONFIG_X86_32
+ PT_REGS_OFFSET(PERF_REG_X86_DS, ds),
+ PT_REGS_OFFSET(PERF_REG_X86_ES, es),
+ PT_REGS_OFFSET(PERF_REG_X86_FS, fs),
+ PT_REGS_OFFSET(PERF_REG_X86_GS, gs),
+#else
+ /*
+ * The pt_regs struct does not store
+ * ds, es, fs, gs in 64 bit mode.
+ */
+ (unsigned int) -1,
+ (unsigned int) -1,
+ (unsigned int) -1,
+ (unsigned int) -1,
+#endif
+#ifdef CONFIG_X86_64
+ PT_REGS_OFFSET(PERF_REG_X86_R8, r8),
+ PT_REGS_OFFSET(PERF_REG_X86_R9, r9),
+ PT_REGS_OFFSET(PERF_REG_X86_R10, r10),
+ PT_REGS_OFFSET(PERF_REG_X86_R11, r11),
+ PT_REGS_OFFSET(PERF_REG_X86_R12, r12),
+ PT_REGS_OFFSET(PERF_REG_X86_R13, r13),
+ PT_REGS_OFFSET(PERF_REG_X86_R14, r14),
+ PT_REGS_OFFSET(PERF_REG_X86_R15, r15),
+#endif
+};
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+ if (WARN_ON_ONCE(idx > ARRAY_SIZE(pt_regs_offset)))
+ return 0;
+
+ return regs_get_register(regs, pt_regs_offset[idx]);
+}
+
+#define REG_RESERVED (~((1ULL << PERF_REG_X86_MAX) - 1ULL))
+
+#ifdef CONFIG_X86_32
+int perf_reg_validate(u64 mask)
+{
+ if (!mask || mask & REG_RESERVED)
+ return -EINVAL;
+
+ return 0;
+}
+#else /* CONFIG_X86_64 */
+#define REG_NOSUPPORT ((1ULL << PERF_REG_X86_DS) | \
+ (1ULL << PERF_REG_X86_ES) | \
+ (1ULL << PERF_REG_X86_FS) | \
+ (1ULL << PERF_REG_X86_GS))
+
+int perf_reg_validate(u64 mask)
+{
+ if (!mask || mask & REG_RESERVED)
+ return -EINVAL;
+
+ if (mask & REG_NOSUPPORT)
+ return -EINVAL;
+
+ return 0;
+}
+#endif /* CONFIG_X86_32 */
diff --git a/include/linux/perf_regs.h b/include/linux/perf_regs.h
new file mode 100644
index 0000000..a2f1a98
--- /dev/null
+++ b/include/linux/perf_regs.h
@@ -0,0 +1,19 @@
+#ifndef _LINUX_PERF_REGS_H
+#define _LINUX_PERF_REGS_H
+
+#ifdef CONFIG_HAVE_PERF_REGS
+#include <asm/perf_regs.h>
+u64 perf_reg_value(struct pt_regs *regs, int idx);
+int perf_reg_validate(u64 mask);
+#else
+static inline u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+ return 0;
+}
+
+static inline int perf_reg_validate(u64 mask)
+{
+ return mask ? -ENOSYS : 0;
+}
+#endif /* CONFIG_HAVE_PERF_REGS */
+#endif /* _LINUX_PERF_REGS_H */
--
1.7.7.6

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