powerpc/perf: Add support for sampling interrupt register state

The perf infrastructure uses a bit mask to find out valid registers to
display. Define a register mask for supported registers defined in
uapi/asm/perf_regs.h. The bit positions also correspond to register IDs
which is used by perf infrastructure to fetch the register values.
CONFIG_HAVE_PERF_REGS enables sampling of the interrupted machine state.

Signed-off-by: Anju T <anju@linux.vnet.ibm.com>
[mpe: Add license, use CONFIG_PPC64, fix 32-bit build]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/Kconfig

@@ -116,6 +116,7 @@ config PPC
 	select GENERIC_ATOMIC64 if PPC32
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
 	select HAVE_PERF_EVENTS
+	select HAVE_PERF_REGS
 	select HAVE_REGS_AND_STACK_ACCESS_API
 	select HAVE_HW_BREAKPOINT if PERF_EVENTS && PPC_BOOK3S_64
 	select ARCH_WANT_IPC_PARSE_VERSION

arch/powerpc/perf/Makefile

@@ -1,6 +1,6 @@
 subdir-ccflags-$(CONFIG_PPC_WERROR) := -Werror
 
-obj-$(CONFIG_PERF_EVENTS)	+= callchain.o
+obj-$(CONFIG_PERF_EVENTS)	+= callchain.o perf_regs.o
 
 obj-$(CONFIG_PPC_PERF_CTRS)	+= core-book3s.o bhrb.o
 obj64-$(CONFIG_PPC_PERF_CTRS)	+= power4-pmu.o ppc970-pmu.o power5-pmu.o \

arch/powerpc/perf/perf_regs.c

@@ -0,0 +1,104 @@
+/*
+ * Copyright 2016 Anju T, IBM Corporation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/perf_event.h>
+#include <linux/bug.h>
+#include <linux/stddef.h>
+#include <asm/ptrace.h>
+#include <asm/perf_regs.h>
+
+#define PT_REGS_OFFSET(id, r) [id] = offsetof(struct pt_regs, r)
+
+#define REG_RESERVED (~((1ULL << PERF_REG_POWERPC_MAX) - 1))
+
+static unsigned int pt_regs_offset[PERF_REG_POWERPC_MAX] = {
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R0,  gpr[0]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R1,  gpr[1]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R2,  gpr[2]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R3,  gpr[3]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R4,  gpr[4]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R5,  gpr[5]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R6,  gpr[6]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R7,  gpr[7]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R8,  gpr[8]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R9,  gpr[9]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R10, gpr[10]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R11, gpr[11]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R12, gpr[12]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R13, gpr[13]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R14, gpr[14]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R15, gpr[15]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R16, gpr[16]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R17, gpr[17]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R18, gpr[18]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R19, gpr[19]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R20, gpr[20]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R21, gpr[21]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R22, gpr[22]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R23, gpr[23]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R24, gpr[24]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R25, gpr[25]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R26, gpr[26]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R27, gpr[27]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R28, gpr[28]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R29, gpr[29]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R30, gpr[30]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_R31, gpr[31]),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_NIP, nip),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_MSR, msr),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_ORIG_R3, orig_gpr3),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_CTR, ctr),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_LINK, link),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_XER, xer),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_CCR, ccr),
+#ifdef CONFIG_PPC64
+	PT_REGS_OFFSET(PERF_REG_POWERPC_SOFTE, softe),
+#else
+	PT_REGS_OFFSET(PERF_REG_POWERPC_SOFTE, mq),
+#endif
+	PT_REGS_OFFSET(PERF_REG_POWERPC_TRAP, trap),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_DAR, dar),
+	PT_REGS_OFFSET(PERF_REG_POWERPC_DSISR, dsisr),
+};
+
+u64 perf_reg_value(struct pt_regs *regs, int idx)
+{
+	if (WARN_ON_ONCE(idx >= PERF_REG_POWERPC_MAX))
+		return 0;
+
+	return regs_get_register(regs, pt_regs_offset[idx]);
+}
+
+int perf_reg_validate(u64 mask)
+{
+	if (!mask || mask & REG_RESERVED)
+		return -EINVAL;
+	return 0;
+}
+
+u64 perf_reg_abi(struct task_struct *task)
+{
+#ifdef CONFIG_PPC64
+	if (!test_tsk_thread_flag(task, TIF_32BIT))
+		return PERF_SAMPLE_REGS_ABI_64;
+	else
+#endif
+	return PERF_SAMPLE_REGS_ABI_32;
+}
+
+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);
+}