Author: attilio
Date: Wed Nov 25 15:23:14 2009
New Revision: 199805
URL: http://svn.freebsd.org/changeset/base/199805
Log:
Change gcore in order to get rid of the procfs accesses and use FreeBSD's
specific sysctls and ptrace interfaces.
This change switches a bit gcore POLA that is summarized here:
- now gcore can recognize threads within the process and handle dumps
on thread-scope
- the process to be analyzed will be stopped during its gcore run
- gcore may not work with processes which are actively being analyzed
by gdb or truss
- the ptrace interface may cause syscalls to return EINTR, thus
interferring with signals handling within the process
Side note: <janitor task> the interface can be further lifted in order to
get rid of the very last procfs interfaces remnants and made more
suitable for copying with sysctl/ptrace interface </janitor task>.
Obtained from: Sandvine Incorporated
Reviewed by: emaste, rwatson
Sponsored by: Sandvine Incorporated
MFC: 1 month
Modified:
head/usr.bin/gcore/Makefile
head/usr.bin/gcore/elfcore.c
head/usr.bin/gcore/gcore.1
head/usr.bin/gcore/gcore.c
Modified: head/usr.bin/gcore/Makefile
==============================================================================
--- head/usr.bin/gcore/Makefile Wed Nov 25 15:12:24 2009 (r199804)
+++ head/usr.bin/gcore/Makefile Wed Nov 25 15:23:14 2009 (r199805)
@@ -1,6 +1,7 @@
# @(#)Makefile 8.1 (Berkeley) 6/6/93
# $FreeBSD$
+LDADD+= -lutil
PROG= gcore
SRCS= elfcore.c gcore.c
Modified: head/usr.bin/gcore/elfcore.c
==============================================================================
--- head/usr.bin/gcore/elfcore.c Wed Nov 25 15:12:24 2009
(r199804)
+++ head/usr.bin/gcore/elfcore.c Wed Nov 25 15:23:14 2009
(r199805)
@@ -1,4 +1,5 @@
/*-
+ * Copyright (c) 2007 Sandvine Incorporated
* Copyright (c) 1998 John D. Polstra
* All rights reserved.
*
@@ -29,8 +30,12 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/procfs.h>
+#include <sys/ptrace.h>
#include <sys/queue.h>
#include <sys/linker_set.h>
+#include <sys/sysctl.h>
+#include <sys/user.h>
+#include <sys/wait.h>
#include <machine/elf.h>
#include <vm/vm_param.h>
#include <vm/vm.h>
@@ -44,6 +49,7 @@ __FBSDID("$FreeBSD$");
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
+#include <libutil.h>
#include "extern.h"
@@ -69,16 +75,15 @@ static void cb_put_phdr(vm_map_entry_t,
static void cb_size_segment(vm_map_entry_t, void *);
static void each_writable_segment(vm_map_entry_t, segment_callback,
void *closure);
-static void elf_corehdr(int fd, pid_t, vm_map_entry_t, int numsegs,
- void *hdr, size_t hdrsize);
-static void elf_puthdr(vm_map_entry_t, void *, size_t *,
- const prstatus_t *, const prfpregset_t *, const prpsinfo_t *, int numsegs);
+static void elf_detach(void); /* atexit() handler. */
+static void elf_puthdr(pid_t, vm_map_entry_t, void *, size_t *, int numsegs);
static void elf_putnote(void *dst, size_t *off, const char *name, int type,
const void *desc, size_t descsz);
static void freemap(vm_map_entry_t);
-static void readhdrinfo(pid_t, prstatus_t *, prfpregset_t *, prpsinfo_t *);
static vm_map_entry_t readmap(pid_t);
+static pid_t g_pid; /* Pid being dumped, global for elf_detach */
+
static int
elf_ident(int efd, pid_t pid __unused, char *binfile __unused)
{
@@ -93,6 +98,14 @@ elf_ident(int efd, pid_t pid __unused, c
return (0);
}
+static void
+elf_detach(void)
+{
+
+ if (g_pid != 0)
+ ptrace(PT_DETACH, g_pid, (caddr_t)1, 0);
+}
+
/*
* Write an ELF coredump for the given pid to the given fd.
*/
@@ -103,11 +116,20 @@ elf_coredump(int efd __unused, int fd, p
struct sseg_closure seginfo;
void *hdr;
size_t hdrsize;
- char memname[64];
- int memfd;
Elf_Phdr *php;
int i;
+ /* Attach to process to dump. */
+ g_pid = pid;
+ if (atexit(elf_detach) != 0)
+ err(1, "atexit");
+ errno = 0;
+ ptrace(PT_ATTACH, pid, NULL, 0);
+ if (errno)
+ err(1, "PT_ATTACH");
+ if (waitpid(pid, NULL, 0) == -1)
+ err(1, "waitpid");
+
/* Get the program's memory map. */
map = readmap(pid);
@@ -122,28 +144,31 @@ elf_coredump(int efd __unused, int fd, p
* size is calculated.
*/
hdrsize = 0;
- elf_puthdr(map, (void *)NULL, &hdrsize,
- (const prstatus_t *)NULL, (const prfpregset_t *)NULL,
- (const prpsinfo_t *)NULL, seginfo.count);
+ elf_puthdr(pid, map, NULL, &hdrsize, seginfo.count);
/*
* Allocate memory for building the header, fill it up,
* and write it out.
*/
- if ((hdr = malloc(hdrsize)) == NULL)
+ if ((hdr = calloc(1, hdrsize)) == NULL)
errx(1, "out of memory");
- elf_corehdr(fd, pid, map, seginfo.count, hdr, hdrsize);
- /* Write the contents of all of the writable segments. */
- snprintf(memname, sizeof memname, "/proc/%d/mem", pid);
- if ((memfd = open(memname, O_RDONLY)) == -1)
- err(1, "cannot open %s", memname);
+ /* Fill in the header. */
+ hdrsize = 0;
+ elf_puthdr(pid, map, hdr, &hdrsize, seginfo.count);
+
+ /* Write it to the core file. */
+ if (write(fd, hdr, hdrsize) == -1)
+ err(1, "write");
+ /* Write the contents of all of the writable segments. */
php = (Elf_Phdr *)((char *)hdr + sizeof(Elf_Ehdr)) + 1;
for (i = 0; i < seginfo.count; i++) {
+ struct ptrace_io_desc iorequest;
uintmax_t nleft = php->p_filesz;
- lseek(memfd, (off_t)php->p_vaddr, SEEK_SET);
+ iorequest.piod_op = PIOD_READ_D;
+ iorequest.piod_offs = (caddr_t)php->p_vaddr;
while (nleft > 0) {
char buf[8*1024];
size_t nwant;
@@ -153,12 +178,12 @@ elf_coredump(int efd __unused, int fd, p
nwant = sizeof buf;
else
nwant = nleft;
- ngot = read(memfd, buf, nwant);
- if (ngot == -1)
- err(1, "read from %s", memname);
+ iorequest.piod_addr = buf;
+ iorequest.piod_len = nwant;
+ ptrace(PT_IO, pid, (caddr_t)&iorequest, 0);
+ ngot = iorequest.piod_len;
if ((size_t)ngot < nwant)
- errx(1, "short read from %s:"
- " wanted %zu, got %zd", memname,
+ errx(1, "short read wanted %d, got %d",
nwant, ngot);
ngot = write(fd, buf, nwant);
if (ngot == -1)
@@ -166,10 +191,10 @@ elf_coredump(int efd __unused, int fd, p
if ((size_t)ngot != nwant)
errx(1, "short write");
nleft -= nwant;
+ iorequest.piod_offs += ngot;
}
php++;
}
- close(memfd);
free(hdr);
freemap(map);
}
@@ -231,30 +256,25 @@ each_writable_segment(vm_map_entry_t map
(*func)(entry, closure);
}
-/*
- * Write the core file header to the file, including padding up to
- * the page boundary.
- */
static void
-elf_corehdr(int fd, pid_t pid, vm_map_entry_t map, int numsegs, void *hdr,
- size_t hdrsize)
+elf_getstatus(pid_t pid, prpsinfo_t *psinfo)
{
- size_t off;
- prstatus_t status;
- prfpregset_t fpregset;
- prpsinfo_t psinfo;
-
- /* Gather the information for the header. */
- readhdrinfo(pid, &status, &fpregset, &psinfo);
-
- /* Fill in the header. */
- memset(hdr, 0, hdrsize);
- off = 0;
- elf_puthdr(map, hdr, &off, &status, &fpregset, &psinfo, numsegs);
-
- /* Write it to the core file. */
- if (write(fd, hdr, hdrsize) == -1)
- err(1, "write");
+ struct kinfo_proc kobj;
+ int name[4];
+ size_t len;
+
+ name[0] = CTL_KERN;
+ name[1] = KERN_PROC;
+ name[2] = KERN_PROC_PID;
+ name[3] = pid;
+
+ len = sizeof(kobj);
+ if (sysctl(name, 4, &kobj, &len, NULL, 0) == -1)
+ err(1, "error accessing kern.proc.pid.%u sysctl", pid);
+ if (kobj.ki_pid != pid)
+ err(1, "error accessing kern.proc.pid.%u sysctl datas", pid);
+ strncpy(psinfo->pr_fname, kobj.ki_comm, MAXCOMLEN);
+ strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
}
/*
@@ -262,13 +282,24 @@ elf_corehdr(int fd, pid_t pid, vm_map_en
* be NULL, in which case the header is sized but not actually generated.
*/
static void
-elf_puthdr(vm_map_entry_t map, void *dst, size_t *off, const prstatus_t
*status,
- const prfpregset_t *fpregset, const prpsinfo_t *psinfo, int numsegs)
+elf_puthdr(pid_t pid, vm_map_entry_t map, void *dst, size_t *off, int numsegs)
{
+ struct {
+ prstatus_t status;
+ prfpregset_t fpregset;
+ prpsinfo_t psinfo;
+ } *tempdata;
size_t ehoff;
size_t phoff;
size_t noteoff;
size_t notesz;
+ size_t threads;
+ lwpid_t *tids;
+ int i;
+
+ prstatus_t *status;
+ prfpregset_t *fpregset;
+ prpsinfo_t *psinfo;
ehoff = *off;
*off += sizeof(Elf_Ehdr);
@@ -277,14 +308,68 @@ elf_puthdr(vm_map_entry_t map, void *dst
*off += (numsegs + 1) * sizeof(Elf_Phdr);
noteoff = *off;
- elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
- sizeof *status);
- elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
- sizeof *fpregset);
+
+ if (dst != NULL) {
+ if ((tempdata = calloc(1, sizeof(*tempdata))) == NULL)
+ errx(1, "out of memory");
+ status = &tempdata->status;
+ fpregset = &tempdata->fpregset;
+ psinfo = &tempdata->psinfo;
+ } else {
+ tempdata = NULL;
+ status = NULL;
+ fpregset = NULL;
+ psinfo = NULL;
+ }
+
+ errno = 0;
+ threads = ptrace(PT_GETNUMLWPS, pid, NULL, 0);
+ if (errno)
+ err(1, "PT_GETNUMLWPS");
+
+ if (dst != NULL) {
+ psinfo->pr_version = PRPSINFO_VERSION;
+ psinfo->pr_psinfosz = sizeof(prpsinfo_t);
+ elf_getstatus(pid, psinfo);
+
+ }
elf_putnote(dst, off, "FreeBSD", NT_PRPSINFO, psinfo,
sizeof *psinfo);
+
+ if (dst != NULL) {
+ tids = malloc(threads * sizeof(*tids));
+ if (tids == NULL)
+ errx(1, "out of memory");
+ errno = 0;
+ ptrace(PT_GETLWPLIST, pid, (void *)tids, threads);
+ if (errno)
+ err(1, "PT_GETLWPLIST");
+ }
+ for (i = 0; i < threads; ++i) {
+ if (dst != NULL) {
+ status->pr_version = PRSTATUS_VERSION;
+ status->pr_statussz = sizeof(prstatus_t);
+ status->pr_gregsetsz = sizeof(gregset_t);
+ status->pr_fpregsetsz = sizeof(fpregset_t);
+ status->pr_osreldate = __FreeBSD_version;
+ status->pr_pid = tids[i];
+
+ ptrace(PT_GETREGS, tids[i], (void *)&status->pr_reg, 0);
+ ptrace(PT_GETFPREGS, tids[i], (void *)fpregset, 0);
+ }
+ elf_putnote(dst, off, "FreeBSD", NT_PRSTATUS, status,
+ sizeof *status);
+ elf_putnote(dst, off, "FreeBSD", NT_FPREGSET, fpregset,
+ sizeof *fpregset);
+ }
+
notesz = *off - noteoff;
+ if (dst != NULL) {
+ free(tids);
+ free(tempdata);
+ }
+
/* Align up to a page boundary for the program segments. */
*off = round_page(*off);
@@ -381,70 +466,7 @@ freemap(vm_map_entry_t map)
}
/*
- * Read the process information necessary to fill in the core file's header.
- */
-static void
-readhdrinfo(pid_t pid, prstatus_t *status, prfpregset_t *fpregset,
- prpsinfo_t *psinfo)
-{
- char name[64];
- char line[256];
- int fd;
- int i;
- int n;
-
- memset(status, 0, sizeof *status);
- status->pr_version = PRSTATUS_VERSION;
- status->pr_statussz = sizeof(prstatus_t);
- status->pr_gregsetsz = sizeof(gregset_t);
- status->pr_fpregsetsz = sizeof(fpregset_t);
- status->pr_osreldate = __FreeBSD_version;
- status->pr_pid = pid;
-
- memset(fpregset, 0, sizeof *fpregset);
-
- memset(psinfo, 0, sizeof *psinfo);
- psinfo->pr_version = PRPSINFO_VERSION;
- psinfo->pr_psinfosz = sizeof(prpsinfo_t);
-
- /* Read the general registers. */
- snprintf(name, sizeof name, "/proc/%d/regs", pid);
- if ((fd = open(name, O_RDONLY)) == -1)
- err(1, "cannot open %s", name);
- if ((n = read(fd, &status->pr_reg, sizeof status->pr_reg)) == -1)
- err(1, "read error from %s", name);
- if ((size_t)n < sizeof(status->pr_reg))
- errx(1, "short read from %s: wanted %zu, got %d", name,
- sizeof status->pr_reg, n);
- close(fd);
-
- /* Read the floating point registers. */
- snprintf(name, sizeof name, "/proc/%d/fpregs", pid);
- if ((fd = open(name, O_RDONLY)) == -1)
- err(1, "cannot open %s", name);
- if ((n = read(fd, fpregset, sizeof *fpregset)) == -1)
- err(1, "read error from %s", name);
- if ((size_t)n < sizeof(*fpregset))
- errx(1, "short read from %s: wanted %zu, got %d", name,
- sizeof *fpregset, n);
- close(fd);
-
- /* Read and parse the process status. */
- snprintf(name, sizeof name, "/proc/%d/status", pid);
- if ((fd = open(name, O_RDONLY)) == -1)
- err(1, "cannot open %s", name);
- if ((n = read(fd, line, sizeof line - 1)) == -1)
- err(1, "read error from %s", name);
- if (n > MAXCOMLEN)
- n = MAXCOMLEN;
- for (i = 0; i < n && line[i] != ' '; i++)
- psinfo->pr_fname[i] = line[i];
- strncpy(psinfo->pr_psargs, psinfo->pr_fname, PRARGSZ);
- close(fd);
-}
-
-/*
- * Read the process's memory map using procfs, and return a list of
+ * Read the process's memory map using kinfo_getvmmap(), and return a list of
* VM map entries. Only the non-device read/writable segments are
* returned. The map entries in the list aren't fully filled in; only
* the items we need are present.
@@ -452,83 +474,44 @@ readhdrinfo(pid_t pid, prstatus_t *statu
static vm_map_entry_t
readmap(pid_t pid)
{
- char mapname[64];
- int mapfd;
- ssize_t mapsize;
- size_t bufsize;
- char *mapbuf;
- int pos;
- vm_map_entry_t map;
- vm_map_entry_t *linkp;
-
- snprintf(mapname, sizeof mapname, "/proc/%d/map", pid);
- if ((mapfd = open(mapname, O_RDONLY)) == -1)
- err(1, "cannot open %s", mapname);
+ vm_map_entry_t ent, *linkp, map;
+ struct kinfo_vmentry *vmentl, *kve;
+ int i, nitems;
+
+ vmentl = kinfo_getvmmap(pid, &nitems);
+ if (vmentl == NULL)
+ err(1, "cannot retrieve mappings for %u process", pid);
- /*
- * Procfs requires (for consistency) that the entire memory map
- * be read with a single read() call. Start with a reasonably sized
- * buffer, and double it until it is big enough.
- */
- bufsize = 8 * 1024;
- mapbuf = NULL;
- for ( ; ; ) {
- if ((mapbuf = realloc(mapbuf, bufsize + 1)) == NULL)
- errx(1, "out of memory");
- mapsize = read(mapfd, mapbuf, bufsize);
- if (mapsize != -1 || errno != EFBIG)
- break;
- bufsize *= 2;
- /* This lseek shouldn't be necessary, but it is. */
- lseek(mapfd, (off_t)0, SEEK_SET);
- }
- if (mapsize == -1)
- err(1, "read error from %s", mapname);
- if (mapsize == 0)
- errx(1, "empty map file %s", mapname);
- mapbuf[mapsize] = 0;
- close(mapfd);
-
- pos = 0;
map = NULL;
linkp = ↦
- while (pos < mapsize) {
- vm_map_entry_t ent;
- u_long start;
- u_long end;
- char prot[4];
- char type[16];
- int n;
- int len;
-
- len = 0;
- n = sscanf(mapbuf + pos, "%lx %lx %*d %*d %*x %3[-rwx]"
- " %*d %*d %*x %*s %*s %16s %*s%*[\n]%n",
- &start, &end, prot, type, &len);
- if (n != 4 || len == 0)
- errx(1, "ill-formed line in %s starting at character
%d", mapname, pos + 1);
- pos += len;
-
- /* Ignore segments of the wrong kind, and unwritable ones */
- if (strncmp(prot, "rw", 2) != 0 ||
- (strcmp(type, "default") != 0 &&
- strcmp(type, "vnode") != 0 &&
- strcmp(type, "swap") != 0))
+ for (i = 0; i < nitems; i++) {
+ kve = &vmentl[i];
+
+ /*
+ * Ignore segments of the wrong kind and ones which are not
+ * readable and writable.
+ */
+ if ((kve->kve_protection & KVME_PROT_WRITE) == 0 ||
+ (kve->kve_protection & KVME_PROT_READ) == 0 ||
+ (kve->kve_type != KVME_TYPE_DEFAULT &&
+ kve->kve_type != KVME_TYPE_VNODE &&
+ kve->kve_type != KVME_TYPE_SWAP))
continue;
- if ((ent = (vm_map_entry_t)calloc(1, sizeof *ent)) == NULL)
+ ent = calloc(1, sizeof(*ent));
+ if (ent == NULL)
errx(1, "out of memory");
- ent->start = start;
- ent->end = end;
+ ent->start = (vm_offset_t)kve->kve_start;
+ ent->end = (vm_offset_t)kve->kve_end;
ent->protection = VM_PROT_READ | VM_PROT_WRITE;
- if (prot[2] == 'x')
- ent->protection |= VM_PROT_EXECUTE;
+ if ((kve->kve_protection & KVME_PROT_EXEC) != 0)
+ ent->protection |= VM_PROT_EXECUTE;
*linkp = ent;
linkp = &ent->next;
}
- free(mapbuf);
- return map;
+ free(vmentl);
+ return (map);
}
struct dumpers elfdump = { elf_ident, elf_coredump };
Modified: head/usr.bin/gcore/gcore.1
==============================================================================
--- head/usr.bin/gcore/gcore.1 Wed Nov 25 15:12:24 2009 (r199804)
+++ head/usr.bin/gcore/gcore.1 Wed Nov 25 15:23:14 2009 (r199805)
@@ -32,7 +32,7 @@
.\" @(#)gcore.1 8.2 (Berkeley) 4/18/94
.\" $FreeBSD$
.\"
-.Dd April 18, 1994
+.Dd November 18, 2009
.Dt GCORE 1
.Os
.Sh NAME
@@ -55,11 +55,6 @@ By default, the core is written to the f
The process identifier,
.Ar pid ,
must be given on the command line.
-If no executable image is
-specified,
-.Nm
-will use
-.Dq Pa /proc/<pid>/file .
.Pp
The following options are available:
.Bl -tag -width indent
@@ -80,8 +75,6 @@ The same effect can be achieved manually
.Bl -tag -width /var/log/messages -compact
.It Pa core.<pid>
the core image
-.It Pa /proc/<pid>/file
-the executable image
.El
.Sh HISTORY
A
@@ -89,12 +82,15 @@ A
utility appeared in
.Bx 4.2 .
.Sh BUGS
-Context switches or paging activity that occur while
-.Nm
-is running may cause the program to become confused.
-For best results, use
-.Fl s
-to temporarily stop the target process.
+Because of the
+.Xr ptrace 2
+usage
+.Nm
+may not work with processes which are actively investigated with
+.Xr truss 1
+or
+.Xr gdb 1 .
+Additionally, interruptable sleeps may exit with EINTR.
.Pp
The
.Nm
Modified: head/usr.bin/gcore/gcore.c
==============================================================================
--- head/usr.bin/gcore/gcore.c Wed Nov 25 15:12:24 2009 (r199804)
+++ head/usr.bin/gcore/gcore.c Wed Nov 25 15:23:14 2009 (r199805)
@@ -61,6 +61,7 @@ __FBSDID("$FreeBSD$");
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/linker_set.h>
+#include <sys/sysctl.h>
#include <err.h>
#include <fcntl.h>
@@ -83,10 +84,11 @@ SET_DECLARE(dumpset, struct dumpers);
int
main(int argc, char *argv[])
{
- int ch, efd, fd, sflag;
+ int ch, efd, fd, name[4], sflag;
char *binfile, *corefile;
- char fname[MAXPATHLEN];
+ char passpath[MAXPATHLEN], fname[MAXPATHLEN];
struct dumpers **d, *dumper;
+ size_t len;
sflag = 0;
corefile = NULL;
@@ -109,9 +111,14 @@ main(int argc, char *argv[])
switch (argc) {
case 1:
pid = atoi(argv[0]);
- asprintf(&binfile, "/proc/%d/file", pid);
- if (binfile == NULL)
- errx(1, "allocation failure");
+ name[0] = CTL_KERN;
+ name[1] = KERN_PROC;
+ name[2] = KERN_PROC_PATHNAME;
+ name[3] = pid;
+ len = sizeof(passpath);
+ if (sysctl(name, 4, passpath, &len, NULL, 0) == -1)
+ errx(1, "kern.proc.pathname failure");
+ binfile = passpath;
break;
case 2:
pid = atoi(argv[1]);
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