[PULL 5/6] linux-user/riscv: add coredump support

[Helge Deller <deller@kernel.org>]

From: Matt Turner <mattst88@gmail.com>

Define HAVE_ELF_CORE_DUMP and target_elf_gregset_t in target_elf.h,
mirroring struct user_regs_struct: pc followed by x1 (ra) through
x31 (t6).  Implement elf_core_copy_regs() in elfload.c to populate
the gregset from CPURISCVState.

Without this, bprm->core_dump is NULL for RISC-V 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-riscv64 process instead of a RISC-V guest core.

Signed-off-by: Matt Turner <mattst88@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/riscv/elfload.c    | 9 +++++++++
 linux-user/riscv/target_elf.h | 7 +++++++
 2 files changed, 16 insertions(+)

diff --git a/linux-user/riscv/elfload.c b/linux-user/riscv/elfload.c
index 2e7d622232..afe103a631 100644
--- a/linux-user/riscv/elfload.c
+++ b/linux-user/riscv/elfload.c
@@ -3,6 +3,7 @@
 #include "qemu/osdep.h"
 #include "qemu.h"
 #include "loader.h"
+#include "target_elf.h"
 
 
 const char *get_elf_cpu_model(uint32_t eflags)
@@ -10,6 +11,14 @@ const char *get_elf_cpu_model(uint32_t eflags)
     return "max";
 }
 
+void elf_core_copy_regs(target_elf_gregset_t *r, const CPURISCVState *env)
+{
+    r->pc = tswapal(env->pc);
+    for (int i = 0; i < 31; i++) {
+        r->regs[i] = tswapal(env->gpr[i + 1]);
+    }
+}
+
 abi_ulong get_elf_hwcap(CPUState *cs)
 {
 #define MISA_BIT(EXT) (1 << (EXT - 'A'))
diff --git a/linux-user/riscv/target_elf.h b/linux-user/riscv/target_elf.h
index dbbfdf54d3..859f726578 100644
--- a/linux-user/riscv/target_elf.h
+++ b/linux-user/riscv/target_elf.h
@@ -19,5 +19,12 @@
 #endif
 
 #define HAVE_ELF_HWCAP          1
+#define HAVE_ELF_CORE_DUMP      1
+
+/* Mirrors struct user_regs_struct: pc followed by x1 (ra) .. x31 (t6). */
+typedef struct target_elf_gregset_t {
+    abi_ulong pc;
+    abi_ulong regs[31];
+} target_elf_gregset_t;
 
 #endif
-- 
2.54.0