[PATCH 2/2] perf tools: Introduce regs_query_register_offset() for arm64

[He Kuang <hekuang@huawei.com>]

Since HAVE_KPROBES can be enabled in arm64, this patch introduces
regs_query_register_offset() to convert register name to offset for
arm64, so the BPF prologue feature is ready to use.

This patch also changes the 'dwarfnum' to 'offset' in register table,
so the related functions are consistent with x86.

Signed-off-by: He Kuang <hekuang@huawei.com>
---
 tools/perf/arch/arm64/Makefile          |   1 +
 tools/perf/arch/arm64/util/dwarf-regs.c | 123 ++++++++++++++++++--------------
 2 files changed, 71 insertions(+), 53 deletions(-)

diff --git a/tools/perf/arch/arm64/Makefile b/tools/perf/arch/arm64/Makefile
index 18b1351..eebe1ec 100644
--- a/tools/perf/arch/arm64/Makefile
+++ b/tools/perf/arch/arm64/Makefile
@@ -2,3 +2,4 @@ ifndef NO_DWARF
 PERF_HAVE_DWARF_REGS := 1
 endif
 PERF_HAVE_JITDUMP := 1
+PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1
diff --git a/tools/perf/arch/arm64/util/dwarf-regs.c b/tools/perf/arch/arm64/util/dwarf-regs.c
index d49efeb..6427ce0 100644
--- a/tools/perf/arch/arm64/util/dwarf-regs.c
+++ b/tools/perf/arch/arm64/util/dwarf-regs.c
@@ -9,72 +9,89 @@
  */
 
 #include <stddef.h>
+#include <linux/ptrace.h> /* for struct user_pt_regs */
+#include <errno.h> /* for EINVAL */
+#include <string.h> /* for strcmp */
 #include <dwarf-regs.h>
 
-struct pt_regs_dwarfnum {
+struct pt_regs_offset {
 	const char *name;
-	unsigned int dwarfnum;
+	int offset;
 };
 
-#define STR(s) #s
-#define REG_DWARFNUM_NAME(r, num) {.name = r, .dwarfnum = num}
-#define GPR_DWARFNUM_NAME(num) \
-	{.name = STR(%x##num), .dwarfnum = num}
-#define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0}
-
 /*
  * Reference:
  * http://infocenter.arm.com/help/topic/com.arm.doc.ihi0057b/IHI0057B_aadwarf64.pdf
  */
-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),
-	REG_DWARFNUM_NAME("%lr", 30),
-	REG_DWARFNUM_NAME("%sp", 31),
-	REG_DWARFNUM_END,
+#define REG_OFFSET_NAME(r) {.name = #r,		\
+			.offset = offsetof(struct user_pt_regs, r)}
+#define REG_OFFSET_END {.name = NULL, .offset = 0}
+#define GPR_OFFSET_NAME(r) \
+	{.name = "%x" #r, .offset = offsetof(struct user_pt_regs, regs[r])}
+
+static const struct pt_regs_offset regoffset_table[] = {
+	GPR_OFFSET_NAME(0),
+	GPR_OFFSET_NAME(1),
+	GPR_OFFSET_NAME(2),
+	GPR_OFFSET_NAME(3),
+	GPR_OFFSET_NAME(4),
+	GPR_OFFSET_NAME(5),
+	GPR_OFFSET_NAME(6),
+	GPR_OFFSET_NAME(7),
+	GPR_OFFSET_NAME(8),
+	GPR_OFFSET_NAME(9),
+	GPR_OFFSET_NAME(10),
+	GPR_OFFSET_NAME(11),
+	GPR_OFFSET_NAME(12),
+	GPR_OFFSET_NAME(13),
+	GPR_OFFSET_NAME(14),
+	GPR_OFFSET_NAME(15),
+	GPR_OFFSET_NAME(16),
+	GPR_OFFSET_NAME(17),
+	GPR_OFFSET_NAME(18),
+	GPR_OFFSET_NAME(19),
+	GPR_OFFSET_NAME(20),
+	GPR_OFFSET_NAME(21),
+	GPR_OFFSET_NAME(22),
+	GPR_OFFSET_NAME(23),
+	GPR_OFFSET_NAME(24),
+	GPR_OFFSET_NAME(25),
+	GPR_OFFSET_NAME(26),
+	GPR_OFFSET_NAME(27),
+	GPR_OFFSET_NAME(28),
+	GPR_OFFSET_NAME(29),
+	GPR_OFFSET_NAME(30),
+	{.name = "lr", .offset = offsetof(struct user_pt_regs, regs[30])},
+	REG_OFFSET_NAME(sp),
+	REG_OFFSET_NAME(pc),
+	REG_OFFSET_NAME(pstate),
+	REG_OFFSET_END,
 };
 
+/* Minus 1 for the ending REG_OFFSET_END */
+#define ARCH_MAX_REGS ((sizeof(regoffset_table) /		\
+			sizeof(regoffset_table[0])) - 1)
+
+/* Return architecture dependent register string (for kprobe-tracer) */
+const char *get_arch_regstr(unsigned int n)
+{
+	return (n < ARCH_MAX_REGS) ? regoffset_table[n].name : NULL;
+}
+
+/* Reuse code from arch/arm64/kernel/ptrace.c */
 /**
- * get_arch_regstr() - lookup register name from it's DWARF register number
- * @n:	the DWARF register number
+ * regs_query_register_offset() - query register offset from its name
+ * @name:	the name of a register
  *
- * 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;
+ * regs_query_register_offset() returns the offset of a register in struct
+ * user_pt_regs from its name. If the name is invalid, this returns -EINVAL;
  */
-const char *get_arch_regstr(unsigned int n)
+int regs_query_register_offset(const char *name)
 {
-	const struct pt_regs_dwarfnum *roff;
-	for (roff = regdwarfnum_table; roff->name != NULL; roff++)
-		if (roff->dwarfnum == n)
-			return roff->name;
-	return NULL;
+	const struct pt_regs_offset *roff;
+
+	for (roff = regoffset_table; roff->name != NULL; roff++)
+		if (!strcmp(roff->name, name))
+			return roff->offset;
+	return -EINVAL;
 }
-- 
1.8.5.2