perf: Unified API to record selective sets of arch registers

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.

Original-patch-by: Frederic Weisbecker <fweisbec@gmail.com>
[ Added missing linux/errno.h include ]
Signed-off-by: Jiri Olsa <jolsa@redhat.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Arun Sharma <asharma@fb.com>
Cc: Benjamin Redelings <benjamin.redelings@nescent.org>
Cc: Corey Ashford <cjashfor@linux.vnet.ibm.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Ulrich Drepper <drepper@gmail.com>
Link: http://lkml.kernel.org/r/1344345647-11536-2-git-send-email-jolsa@redhat.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 92 insertions, 0 deletions

diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8215e5652d97..8d7a619718b5 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 000000000000..3d6923528b1c
--- /dev/null
+++ b/arch/x86/kernel/perf_regs.c
@@ -0,0 +1,90 @@
+#include <linux/errno.h>
+#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 */