Make use of the fact that target_elf_gregset_t is a
proper structure by using target_user_pt_regs.

Drop ELF_NREG, target_elf_greg_t, and tswapreg.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 linux-user/aarch64/target_elf.h | 11 +++++++----
 linux-user/aarch64/elfload.c    | 11 +++++------
 2 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/linux-user/aarch64/target_elf.h b/linux-user/aarch64/target_elf.h
index b0728a1008..9eb8bb547e 100644
--- a/linux-user/aarch64/target_elf.h
+++ b/linux-user/aarch64/target_elf.h
@@ -8,16 +8,19 @@
 #ifndef AARCH64_TARGET_ELF_H
 #define AARCH64_TARGET_ELF_H
 
+#include "target_ptrace.h"
+
 #define HAVE_ELF_HWCAP          1
 #define HAVE_ELF_HWCAP2         1
 #define HAVE_ELF_PLATFORM       1
 #define HAVE_ELF_CORE_DUMP      1
 
-typedef abi_ulong target_elf_greg_t;
-
-#define ELF_NREG                34
+/*
+ * See linux kernel: arch/arm64/include/asm/elf.h, where
+ * elf_gregset_t is mapped to struct user_pt_regs via sizeof.
+ */
 typedef struct target_elf_gregset_t {
-    target_elf_greg_t regs[ELF_NREG];
+    struct target_user_pt_regs pt;
 } target_elf_gregset_t;
 
 #endif
diff --git a/linux-user/aarch64/elfload.c b/linux-user/aarch64/elfload.c
index 00550f9fdf..07a0c3f844 100644
--- a/linux-user/aarch64/elfload.c
+++ b/linux-user/aarch64/elfload.c
@@ -349,13 +349,12 @@ const char *get_elf_platform(CPUState *cs)
     return TARGET_BIG_ENDIAN ? "aarch64_be" : "aarch64";
 }
 
-#define tswapreg(ptr)   tswapal(ptr)
-
 void elf_core_copy_regs(target_elf_gregset_t *r, const CPUARMState *env)
 {
-    for (int i = 0; i < 32; i++) {
-        r->regs[i] = tswapreg(env->xregs[i]);
+    for (int i = 0; i < 31; i++) {
+        r->pt.regs[i] = tswap64(env->xregs[i]);
     }
-    r->regs[32] = tswapreg(env->pc);
-    r->regs[33] = tswapreg(pstate_read((CPUARMState *)env));
+    r->pt.sp = tswap64(env->xregs[31]);
+    r->pt.pc = tswap64(env->pc);
+    r->pt.pstate = tswap64(pstate_read((CPUARMState *)env));
 }
-- 
2.43.0