[PATCH v2 2/2] perf probe: Add PowerPC DWARF register number mappings

[Ian Munsie]

From: Ian Munsie <imunsie at au.ibm.com>

This patch adds mappings from the register numbers from DWARF to the
register names used in the PowerPC Regs and Stack Access API. This
allows perf probe to be used to record variable contents on PowerPC.

This patch depends on functionality in the powerpc/next tree, though it
will compile fine without it. Specifically this patch depends on commit
"powerpc: Add kprobe-based event tracer"

Signed-off-by: Ian Munsie <imunsie at au.ibm.com>
---
 Changes since v1: Removed arch specific arch_dwarf-regs.h and defined
 PERF_HAVE_DWARF_REGS in the arch specific Makefile.

 tools/perf/arch/powerpc/Makefile          |    2 +
 tools/perf/arch/powerpc/util/dwarf-regs.c |   88 +++++++++++++++++++++++++++++
 2 files changed, 90 insertions(+), 0 deletions(-)
 create mode 100644 tools/perf/arch/powerpc/Makefile
 create mode 100644 tools/perf/arch/powerpc/util/dwarf-regs.c

diff --git a/tools/perf/arch/powerpc/Makefile b/tools/perf/arch/powerpc/Makefile
new file mode 100644
index 0000000..cbd7833
--- /dev/null
+++ b/tools/perf/arch/powerpc/Makefile
@@ -0,0 +1,2 @@
+PERF_HAVE_DWARF_REGS := 1
+LIB_OBJS += $(OUTPUT)arch/$(ARCH)/util/dwarf-regs.o
diff --git a/tools/perf/arch/powerpc/util/dwarf-regs.c b/tools/perf/arch/powerpc/util/dwarf-regs.c
new file mode 100644
index 0000000..48ae0c5
--- /dev/null
+++ b/tools/perf/arch/powerpc/util/dwarf-regs.c
@@ -0,0 +1,88 @@
+/*
+ * Mapping of DWARF debug register numbers into register names.
+ *
+ * Copyright (C) 2010 Ian Munsie, 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 <libio.h>
+#include <dwarf-regs.h>
+
+
+struct pt_regs_dwarfnum {
+	const char *name;
+	unsigned int dwarfnum;
+};
+
+#define STR(s) #s
+#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num}
+#define GPR_DWARFNUM_NAME(num)	\
+	{.name = STR(%gpr##num), .dwarfnum = num}
+#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0}
+
+/*
+ * Reference:
+ * http://refspecs.linuxfoundation.org/ELF/ppc64/PPC-elf64abi-1.9.html
+ */
+static const struct pt_regs_dwarfnum regdwarfnum_table[] = {
+	GPR_DWARFNUM_NAME(0),
+	GPR_DWARFNUM_NAME(1),
+	GPR_DWARFNUM_NAME(2),
+	GPR_DWARFNUM_NAME(3),
+	GPR_DWARFNUM_NAME(4),
+	GPR_DWARFNUM_NAME(5),
+	GPR_DWARFNUM_NAME(6),
+	GPR_DWARFNUM_NAME(7),
+	GPR_DWARFNUM_NAME(8),
+	GPR_DWARFNUM_NAME(9),
+	GPR_DWARFNUM_NAME(10),
+	GPR_DWARFNUM_NAME(11),
+	GPR_DWARFNUM_NAME(12),
+	GPR_DWARFNUM_NAME(13),
+	GPR_DWARFNUM_NAME(14),
+	GPR_DWARFNUM_NAME(15),
+	GPR_DWARFNUM_NAME(16),
+	GPR_DWARFNUM_NAME(17),
+	GPR_DWARFNUM_NAME(18),
+	GPR_DWARFNUM_NAME(19),
+	GPR_DWARFNUM_NAME(20),
+	GPR_DWARFNUM_NAME(21),
+	GPR_DWARFNUM_NAME(22),
+	GPR_DWARFNUM_NAME(23),
+	GPR_DWARFNUM_NAME(24),
+	GPR_DWARFNUM_NAME(25),
+	GPR_DWARFNUM_NAME(26),
+	GPR_DWARFNUM_NAME(27),
+	GPR_DWARFNUM_NAME(28),
+	GPR_DWARFNUM_NAME(29),
+	GPR_DWARFNUM_NAME(30),
+	GPR_DWARFNUM_NAME(31),
+	REG_DWARFNUM_NAME("%msr",   66),
+	REG_DWARFNUM_NAME("%ctr",   109),
+	REG_DWARFNUM_NAME("%link",  108),
+	REG_DWARFNUM_NAME("%xer",   101),
+	REG_DWARFNUM_NAME("%dar",   119),
+	REG_DWARFNUM_NAME("%dsisr", 118),
+	REG_DWARFNUM_END,
+};
+
+/**
+ * get_arch_regstr() - lookup register name from it's DWARF register number
+ * @n:	the DWARF register number
+ *
+ * get_arch_regstr() returns the name of the register in struct
+ * regdwarfnum_table from it's DWARF register number. If the register is not
+ * found in the table, this returns NULL;
+ */
+const char *get_arch_regstr(unsigned int n)
+{
+	const struct pt_regs_dwarfnum *roff;
+	for (roff = regdwarfnum_table; roff->name != NULL; roff++)
+		if (roff->dwarfnum == n)
+			return roff->name;
+	return NULL;
+}
-- 
1.7.0