Make use of the fact that target_elf_gregset_t is a proper structure.
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/ppc/target_elf.h | 16 +++++++++++-----
 linux-user/ppc/elfload.c    | 23 ++++++++---------------
 2 files changed, 19 insertions(+), 20 deletions(-)

diff --git a/linux-user/ppc/target_elf.h b/linux-user/ppc/target_elf.h
index 72615553ea..2a61cd2896 100644
--- a/linux-user/ppc/target_elf.h
+++ b/linux-user/ppc/target_elf.h
@@ -8,16 +8,22 @@
 #ifndef PPC_TARGET_ELF_H
 #define PPC_TARGET_ELF_H
 
+#include "target_ptrace.h"
+
 #define HAVE_ELF_HWCAP          1
 #define HAVE_ELF_HWCAP2         1
 #define HAVE_ELF_CORE_DUMP      1
 
-typedef abi_ulong target_elf_greg_t;
-
-/* See linux kernel: arch/powerpc/include/asm/elf.h.  */
-#define ELF_NREG                48
+/*
+ * The size of 48 words is set in arch/powerpc/include/uapi/asm/elf.h.
+ * However PPC_ELF_CORE_COPY_REGS in arch/powerpc/include/asm/elf.h
+ * open-codes a memcpy from struct pt_regs, then zeros the rest.
+ */
 typedef struct target_elf_gregset_t {
-    target_elf_greg_t regs[ELF_NREG];
+    union {
+        struct target_pt_regs pt;
+        abi_ulong reserved[48];
+    };
 } target_elf_gregset_t;
 
 #endif
diff --git a/linux-user/ppc/elfload.c b/linux-user/ppc/elfload.c
index 114e40a358..0d54da9803 100644
--- a/linux-user/ppc/elfload.c
+++ b/linux-user/ppc/elfload.c
@@ -131,23 +131,16 @@ abi_ulong get_elf_hwcap2(CPUState *cs)
     return features;
 }
 
-#define tswapreg(ptr)   tswapal(ptr)
-
 void elf_core_copy_regs(target_elf_gregset_t *r, const CPUPPCState *env)
 {
-    int i;
-    target_ulong ccr = 0;
-
-    for (i = 0; i < ARRAY_SIZE(env->gpr); i++) {
-        r->regs[i] = tswapreg(env->gpr[i]);
+    for (int i = 0; i < ARRAY_SIZE(env->gpr); i++) {
+        r->pt.gpr[i] = tswapal(env->gpr[i]);
     }
 
-    r->regs[32] = tswapreg(env->nip);
-    r->regs[33] = tswapreg(env->msr);
-    r->regs[35] = tswapreg(env->ctr);
-    r->regs[36] = tswapreg(env->lr);
-    r->regs[37] = tswapreg(cpu_read_xer(env));
-
-    ccr = ppc_get_cr(env);
-    r->regs[38] = tswapreg(ccr);
+    r->pt.nip = tswapal(env->nip);
+    r->pt.msr = tswapal(env->msr);
+    r->pt.ctr = tswapal(env->ctr);
+    r->pt.link = tswapal(env->lr);
+    r->pt.xer = tswapal(cpu_read_xer(env));
+    r->pt.ccr = tswapal(ppc_get_cr(env));
 }
-- 
2.43.0