dump: Consolidate phdr note writes

There's no need to have two write functions. Let's rather have two
functions that set the data for elf 32/64 and then write it in a
common function.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20220330123603.107120-8-frankja@linux.ibm.com>

dump/dump.c

@@ -245,24 +245,15 @@ static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
     }
 }
 
-static void write_elf64_note(DumpState *s, Error **errp)
+static void write_elf64_phdr_note(DumpState *s, Elf64_Phdr *phdr)
 {
-    Elf64_Phdr phdr;
-    int ret;
-
-    memset(&phdr, 0, sizeof(Elf64_Phdr));
-    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump64(s, s->note_offset);
-    phdr.p_paddr = 0;
-    phdr.p_filesz = cpu_to_dump64(s, s->note_size);
-    phdr.p_memsz = cpu_to_dump64(s, s->note_size);
-    phdr.p_vaddr = 0;
-
-    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret,
-                         "dump: failed to write program header table");
-    }
+    memset(phdr, 0, sizeof(*phdr));
+    phdr->p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr->p_offset = cpu_to_dump64(s, s->note_offset);
+    phdr->p_paddr = 0;
+    phdr->p_filesz = cpu_to_dump64(s, s->note_size);
+    phdr->p_memsz = cpu_to_dump64(s, s->note_size);
+    phdr->p_vaddr = 0;
 }
 
 static inline int cpu_index(CPUState *cpu)
@@ -310,24 +301,15 @@ static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
     write_guest_note(f, s, errp);
 }
 
-static void write_elf32_note(DumpState *s, Error **errp)
+static void write_elf32_phdr_note(DumpState *s, Elf32_Phdr *phdr)
 {
-    Elf32_Phdr phdr;
-    int ret;
-
-    memset(&phdr, 0, sizeof(Elf32_Phdr));
-    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
-    phdr.p_offset = cpu_to_dump32(s, s->note_offset);
-    phdr.p_paddr = 0;
-    phdr.p_filesz = cpu_to_dump32(s, s->note_size);
-    phdr.p_memsz = cpu_to_dump32(s, s->note_size);
-    phdr.p_vaddr = 0;
-
-    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
-    if (ret < 0) {
-        error_setg_errno(errp, -ret,
-                         "dump: failed to write program header table");
-    }
+    memset(phdr, 0, sizeof(*phdr));
+    phdr->p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr->p_offset = cpu_to_dump32(s, s->note_offset);
+    phdr->p_paddr = 0;
+    phdr->p_filesz = cpu_to_dump32(s, s->note_size);
+    phdr->p_memsz = cpu_to_dump32(s, s->note_size);
+    phdr->p_vaddr = 0;
 }
 
 static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
@@ -357,6 +339,32 @@ static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
     write_guest_note(f, s, errp);
 }
 
+static void write_elf_phdr_note(DumpState *s, Error **errp)
+{
+    ERRP_GUARD();
+    Elf32_Phdr phdr32;
+    Elf64_Phdr phdr64;
+    void *phdr;
+    size_t size;
+    int ret;
+
+    if (dump_is_64bit(s)) {
+        write_elf64_phdr_note(s, &phdr64);
+        size = sizeof(phdr64);
+        phdr = &phdr64;
+    } else {
+        write_elf32_phdr_note(s, &phdr32);
+        size = sizeof(phdr32);
+        phdr = &phdr32;
+    }
+
+    ret = fd_write_vmcore(phdr, size, s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
 static void write_elf_section(DumpState *s, int type, Error **errp)
 {
     Elf32_Shdr shdr32;
@@ -550,13 +558,13 @@ static void dump_begin(DumpState *s, Error **errp)
         return;
     }
 
-    if (dump_is_64bit(s)) {
-        /* write PT_NOTE to vmcore */
-        write_elf64_note(s, errp);
-        if (*errp) {
-            return;
-        }
+    /* write PT_NOTE to vmcore */
+    write_elf_phdr_note(s, errp);
+    if (*errp) {
+        return;
+    }
 
+    if (dump_is_64bit(s)) {
         /* write all PT_LOAD to vmcore */
         write_elf_loads(s, errp);
         if (*errp) {
@@ -577,12 +585,6 @@ static void dump_begin(DumpState *s, Error **errp)
             return;
         }
     } else {
-        /* write PT_NOTE to vmcore */
-        write_elf32_note(s, errp);
-        if (*errp) {
-            return;
-        }
-
         /* write all PT_LOAD to vmcore */
         write_elf_loads(s, errp);
         if (*errp) {