perf tools arm64: Add support for generating bpf prologue

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.

Signed-off-by: He Kuang <[e-mail]>
Reviewed-by: Will Deacon <[e-mail]>
Acked-by: Masami Hiramatsu <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Bintian Wang <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Wang Nan <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/arch/arm64/Makefile

···
 PERF_HAVE_DWARF_REGS := 1
 endif
 PERF_HAVE_JITDUMP := 1
+PERF_HAVE_ARCH_REGS_QUERY_REGISTER_OFFSET := 1

tools/perf/arch/arm64/util/dwarf-regs.c

···
 
 #include <stddef.h>
 #include <dwarf-regs.h>
+#include <linux/ptrace.h> /* for struct user_pt_regs */
+#include "util.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(%x##num), .dwarfnum = num}
 #define REG_DWARFNUM_END {.name = NULL, .dwarfnum = 0}
+#define DWARFNUM2OFFSET(index) \
+	(index * sizeof((struct user_pt_regs *)0)->regs[0])
 
 /*
  * Reference:
···
 		if (roff->dwarfnum == n)
 			return roff->name;
 	return NULL;
+}
+
+int regs_query_register_offset(const char *name)
+{
+	const struct pt_regs_dwarfnum *roff;
+
+	for (roff = regdwarfnum_table; roff->name != NULL; roff++)
+		if (!strcmp(roff->name, name))
+			return DWARFNUM2OFFSET(roff->dwarfnum);
+	return -EINVAL;
 }