linux-user/mips: write the floating-point registers to a core dump

Write an NT_FPREGSET note for MIPS and MIPS64, matching the kernel's
elf_fpregset_t layout (ELF_NFPREG = 33): fpr[0..31] hold f0-f31, and
fcsr occupies the low 32 bits of slot 32.  The pad field rounds the
struct to 33 × 8 bytes = 264 bytes.

Signed-off-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Helge Deller <deller@gmx.de>
Signed-off-by: Helge Deller <deller@gmx.de>

linux-user/mips/elfload.c

@@ -130,6 +130,14 @@ const char *get_elf_base_platform(CPUState *cs)
 
 #undef MATCH_PLATFORM_INSN
 
+void elf_core_copy_fpregs(target_elf_fpregset_t *r, const CPUMIPSState *env)
+{
+    for (int i = 0; i < 32; i++) {
+        r->fpr[i] = tswap64(env->active_fpu.fpr[i].d);
+    }
+    r->fcsr = tswap32(env->active_fpu.fcr31);
+}
+
 /* See linux kernel: arch/mips/kernel/process.c:elf_dump_regs.  */
 #ifndef TARGET_MIPS64
 void elf_core_copy_regs(target_elf_gregset_t *r, const CPUMIPSState *env)

linux-user/mips/target_elf.h

@@ -26,4 +26,17 @@ typedef struct target_elf_gregset_t {
     };
 } target_elf_gregset_t;
 
+#define HAVE_ELF_CORE_FPREGS    1
+
+/*
+ * Matches the kernel's elf_fpregset_t (ELF_NFPREG = 33):
+ *   fpr[0..31] hold f0-f31; fcsr occupies the low 32 bits of slot 32.
+ *   pad rounds the struct to 33 × 8 bytes = 264 bytes.
+ */
+typedef struct target_elf_fpregset_t {
+    uint64_t fpr[32];
+    uint32_t fcsr;
+    uint32_t pad;
+} target_elf_fpregset_t;
+
 #endif

linux-user/mips64/target_elf.h

@@ -32,4 +32,17 @@ typedef struct target_elf_gregset_t {
     };
 } target_elf_gregset_t;
 
+#define HAVE_ELF_CORE_FPREGS    1
+
+/*
+ * Matches the kernel's elf_fpregset_t (ELF_NFPREG = 33):
+ *   fpr[0..31] hold f0-f31; fcsr occupies the low 32 bits of slot 32.
+ *   pad rounds the struct to 33 × 8 bytes = 264 bytes.
+ */
+typedef struct target_elf_fpregset_t {
+    uint64_t fpr[32];
+    uint32_t fcsr;
+    uint32_t pad;
+} target_elf_fpregset_t;
+
 #endif