Define HAVE_ELF_CORE_DUMP and target_elf_gregset_t in target_elf.h,
mirroring the kernel's elf_gregset_t (ELF_NGREG = 66): r0-r31
[0..31], f0-f31 [32..63], pc [64], ps [65].  Implement
elf_core_copy_regs() in elfload.c to populate the gregset from
CPUAlphaState.

Without this, bprm->core_dump is NULL for Alpha targets.  When a
guest signal goes unhandled, dump_core_and_abort() skips the core
write and falls through to die_with_signal(), which re-raises the
signal to the host.  The host kernel then writes an x86-64 core file
for the qemu-alpha process instead of an Alpha guest core.

Signed-off-by: Matt Turner <mattst88@gmail.com>
---
 linux-user/alpha/elfload.c    | 12 ++++++++++++
 linux-user/alpha/target_elf.h | 13 +++++++++++++
 2 files changed, 25 insertions(+)

diff --git ./linux-user/alpha/elfload.c ./linux-user/alpha/elfload.c
index 1e44475c47..c86f9cf2bb 100644
--- ./linux-user/alpha/elfload.c
+++ ./linux-user/alpha/elfload.c
@@ -3,8 +3,20 @@
 #include "qemu/osdep.h"
 #include "qemu.h"
 #include "loader.h"
+#include "target_elf.h"
 
 
+void elf_core_copy_regs(target_elf_gregset_t *r, const CPUAlphaState *env)
+{
+    int i;
+
+    for (i = 0; i < 31; i++) {
+        r->regs[i] = tswap64(env->ir[i]);
+    }
+    r->pc = tswap64(env->pc);
+    r->ps = 0;
+}
+
 const char *get_elf_cpu_model(uint32_t eflags)
 {
     return "ev67";
diff --git ./linux-user/alpha/target_elf.h ./linux-user/alpha/target_elf.h
index 864dc6e2e6..bf3bd21b09 100644
--- ./linux-user/alpha/target_elf.h
+++ ./linux-user/alpha/target_elf.h
@@ -11,4 +11,17 @@
 #define ELF_CLASS               ELFCLASS64
 #define ELF_MACHINE             EM_ALPHA
 
+#define HAVE_ELF_CORE_DUMP      1
+
+/*
+ * Matches the kernel's elf_gregset_t (ELF_NGREG = 33):
+ *   r0-r30 at indices 0-30, pc at 31, ps at 32.
+ * r31 (hardwired zero) is not stored; pc occupies index 31.
+ */
+typedef struct target_elf_gregset_t {
+    abi_ulong regs[31];  /* integer registers r0-r30  [0..30] */
+    abi_ulong pc;        /* program counter           [31]    */
+    abi_ulong ps;        /* processor status          [32]    */
+} target_elf_gregset_t;
+
 #endif
-- 
2.53.0