MFC 313407,313449: Copy ELF machine/flags from binaries to core dumps.

313407:
Copy the e_machine and e_flags fields from the binary into an ELF core dump.

In the kernel, cache the machine and flags fields from ELF header to use in
the ELF header of a core dump. For gcore, the copy these fields over from
the ELF header in the binary.

This matters for platforms which encode ABI information in the flags field
(such as o32 vs n32 on MIPS).

313449:
Trim trailing whitespace (mostly introduced in r313407).

Sponsored by:	DARPA / AFRL

1 files changed, 15 insertions, 8 deletions

diff --git a/usr.bin/gcore/elfcore.c b/usr.bin/gcore/elfcore.c
index 6f617ee..0a09888 100644
--- a/usr.bin/gcore/elfcore.c
+++ b/usr.bin/gcore/elfcore.c
@@ -117,8 +117,8 @@ static void *elf_note_procstat_psstrings(void *, size_t *);
 static void *elf_note_procstat_rlimit(void *, size_t *);
 static void *elf_note_procstat_umask(void *, size_t *);
 static void *elf_note_procstat_vmmap(void *, size_t *);
-static void elf_puthdr(pid_t, vm_map_entry_t, void *, size_t, size_t, size_t,
-    int);
+static void elf_puthdr(int, pid_t, vm_map_entry_t, void *, size_t, size_t,
+    size_t, int);
 static void elf_putnote(int, notefunc_t, void *, struct sbuf *);
 static void elf_putnotes(pid_t, struct sbuf *, size_t *);
 static void freemap(vm_map_entry_t);
@@ -178,7 +178,7 @@ elf_detach(void)
  * Write an ELF coredump for the given pid to the given fd.
  */
 static void
-elf_coredump(int efd __unused, int fd, pid_t pid)
+elf_coredump(int efd, int fd, pid_t pid)
 {
 	vm_map_entry_t map;
 	struct sseg_closure seginfo;
@@ -228,7 +228,7 @@ elf_coredump(int efd __unused, int fd, pid_t pid)
 	hdr = sbuf_data(sb);
 	segoff = sbuf_len(sb);
 	/* Fill in the header. */
-	elf_puthdr(pid, map, hdr, hdrsize, notesz, segoff, seginfo.count);
+	elf_puthdr(efd, pid, map, hdr, hdrsize, notesz, segoff, seginfo.count);
 
 	n = write(fd, hdr, segoff);
 	if (n == -1)
@@ -418,12 +418,19 @@ elf_putnote(int type, notefunc_t notefunc, void *arg, struct sbuf *sb)
  * Generate the ELF coredump header.
  */
 static void
-elf_puthdr(pid_t pid, vm_map_entry_t map, void *hdr, size_t hdrsize,
+elf_puthdr(int efd, pid_t pid, vm_map_entry_t map, void *hdr, size_t hdrsize,
     size_t notesz, size_t segoff, int numsegs)
 {
-	Elf_Ehdr *ehdr;
+	Elf_Ehdr *ehdr, binhdr;
 	Elf_Phdr *phdr;
 	struct phdr_closure phc;
+	ssize_t cnt;
+
+	cnt = read(efd, &binhdr, sizeof(binhdr));
+	if (cnt < 0)
+		err(1, "Failed to re-read ELF header");
+	else if (cnt != sizeof(binhdr))
+		errx(1, "Failed to re-read ELF header");
 
 	ehdr = (Elf_Ehdr *)hdr;
 	phdr = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr));
@@ -439,11 +446,11 @@ elf_puthdr(pid_t pid, vm_map_entry_t map, void *hdr, size_t hdrsize,
 	ehdr->e_ident[EI_ABIVERSION] = 0;
 	ehdr->e_ident[EI_PAD] = 0;
 	ehdr->e_type = ET_CORE;
-	ehdr->e_machine = ELF_ARCH;
+	ehdr->e_machine = binhdr.e_machine;
 	ehdr->e_version = EV_CURRENT;
 	ehdr->e_entry = 0;
 	ehdr->e_phoff = sizeof(Elf_Ehdr);
-	ehdr->e_flags = 0;
+	ehdr->e_flags = binhdr.e_flags;
 	ehdr->e_ehsize = sizeof(Elf_Ehdr);
 	ehdr->e_phentsize = sizeof(Elf_Phdr);
 	ehdr->e_phnum = numsegs + 1;