svn commit: r313407 - in head: sys/kern sys/sys usr.bin/gcore

[John Baldwin]

Author: jhb
Date: Tue Feb  7 20:34:03 2017
New Revision: 313407
URL: https://svnweb.freebsd.org/changeset/base/313407

Log:
  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).
  
  Reviewed by:	kib
  Sponsored by:	DARPA / AFRL
  Differential Revision:	https://reviews.freebsd.org/D9392

Modified:
  head/sys/kern/imgact_elf.c
  head/sys/sys/proc.h
  head/usr.bin/gcore/elfcore.c

Modified: head/sys/kern/imgact_elf.c
==============================================================================
--- head/sys/kern/imgact_elf.c	Tue Feb  7 19:47:30 2017	(r313406)
+++ head/sys/kern/imgact_elf.c	Tue Feb  7 20:34:03 2017	(r313407)
@@ -1055,6 +1055,8 @@ __CONCAT(exec_, __elfN(imgact))(struct i
 	imgp->interpreted = 0;
 	imgp->reloc_base = addr;
 	imgp->proc->p_osrel = osrel;
+	imgp->proc->p_elf_machine = hdr->e_machine;
+	imgp->proc->p_elf_flags = hdr->e_flags;
 
 ret:
 	free(interp_buf, M_TEMP);
@@ -1655,15 +1657,11 @@ __elfN(puthdr)(struct thread *td, void *
 	ehdr->e_ident[EI_ABIVERSION] = 0;
 	ehdr->e_ident[EI_PAD] = 0;
 	ehdr->e_type = ET_CORE;
-#if defined(COMPAT_FREEBSD32) && __ELF_WORD_SIZE == 32
-	ehdr->e_machine = ELF_ARCH32;
-#else
-	ehdr->e_machine = ELF_ARCH;
-#endif
+	ehdr->e_machine = td->td_proc->p_elf_machine;
 	ehdr->e_version = EV_CURRENT;
 	ehdr->e_entry = 0;
 	ehdr->e_phoff = sizeof(Elf_Ehdr);
-	ehdr->e_flags = 0;
+	ehdr->e_flags = td->td_proc->p_elf_flags;
 	ehdr->e_ehsize = sizeof(Elf_Ehdr);
 	ehdr->e_phentsize = sizeof(Elf_Phdr);
 	ehdr->e_shentsize = sizeof(Elf_Shdr);

Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h	Tue Feb  7 19:47:30 2017	(r313406)
+++ head/sys/sys/proc.h	Tue Feb  7 20:34:03 2017	(r313407)
@@ -617,8 +617,11 @@ struct proc {
 					       our subtree. */
 	u_int		p_xexit;	/* (c) Exit code. */
 	u_int		p_xsig;		/* (c) Stop/kill sig. */
+	uint16_t	p_elf_machine;	/* (x) ELF machine type */
+	uint64_t	p_elf_flags;	/* (x) ELF flags */
+	
 /* End area that is copied on creation. */
-#define	p_endcopy	p_xsig
+#define	p_endcopy	p_elf_flags
 	struct pgrp	*p_pgrp;	/* (c + e) Pointer to process group. */
 	struct knlist	*p_klist;	/* (c) Knotes attached to this proc. */
 	int		p_numthreads;	/* (c) Number of threads. */

Modified: head/usr.bin/gcore/elfcore.c
==============================================================================
--- head/usr.bin/gcore/elfcore.c	Tue Feb  7 19:47:30 2017	(r313406)
+++ head/usr.bin/gcore/elfcore.c	Tue Feb  7 20:34:03 2017	(r313407)
@@ -117,8 +117,8 @@ static void *elf_note_procstat_psstrings
 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;
@@ -230,7 +230,7 @@ elf_coredump(int efd __unused, int fd, p
 	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)
@@ -420,14 +420,21 @@ elf_putnote(int type, notefunc_t notefun
  * 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;
 	Elf_Shdr *shdr;
 	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;
 
 	ehdr->e_ident[EI_MAG0] = ELFMAG0;
@@ -441,11 +448,11 @@ elf_puthdr(pid_t pid, vm_map_entry_t map
 	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_shentsize = sizeof(Elf_Shdr);