Squashed 'third_party/elfutils/' content from commit 555e15e
Change-Id: I61cde98949e47e5c8c09c33260de17f30921be79
git-subtree-dir: third_party/elfutils
git-subtree-split: 555e15ebe8bf1eb33d00747173cfc80cc65648a4
diff --git a/libdwfl/linux-proc-maps.c b/libdwfl/linux-proc-maps.c
new file mode 100644
index 0000000..c4438c0
--- /dev/null
+++ b/libdwfl/linux-proc-maps.c
@@ -0,0 +1,440 @@
+/* Standard libdwfl callbacks for debugging a live Linux process.
+ Copyright (C) 2005-2010, 2013, 2014, 2016 Red Hat, Inc.
+ This file is part of elfutils.
+
+ This file is free software; you can redistribute it and/or modify
+ it under the terms of either
+
+ * the GNU Lesser General Public License as published by the Free
+ Software Foundation; either version 3 of the License, or (at
+ your option) any later version
+
+ or
+
+ * the GNU General Public License as published by the Free
+ Software Foundation; either version 2 of the License, or (at
+ your option) any later version
+
+ or both in parallel, as here.
+
+ elfutils is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ General Public License for more details.
+
+ You should have received copies of the GNU General Public License and
+ the GNU Lesser General Public License along with this program. If
+ not, see <http://www.gnu.org/licenses/>. */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include "libdwflP.h"
+#include <inttypes.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdio_ext.h>
+#include <stdbool.h>
+#include <string.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <assert.h>
+#include <endian.h>
+#include "system.h"
+
+
+#define PROCMAPSFMT "/proc/%d/maps"
+#define PROCMEMFMT "/proc/%d/mem"
+#define PROCAUXVFMT "/proc/%d/auxv"
+#define PROCEXEFMT "/proc/%d/exe"
+
+
+/* Return ELFCLASS64 or ELFCLASS32 for the main ELF executable. Return
+ ELFCLASSNONE for an error. */
+
+static unsigned char
+get_pid_class (pid_t pid)
+{
+ char *fname;
+ if (asprintf (&fname, PROCEXEFMT, pid) < 0)
+ return ELFCLASSNONE;
+
+ int fd = open (fname, O_RDONLY);
+ free (fname);
+ if (fd < 0)
+ return ELFCLASSNONE;
+
+ unsigned char buf[EI_CLASS + 1];
+ ssize_t nread = pread_retry (fd, &buf, sizeof buf, 0);
+ close (fd);
+ if (nread != sizeof buf || buf[EI_MAG0] != ELFMAG0
+ || buf[EI_MAG1] != ELFMAG1 || buf[EI_MAG2] != ELFMAG2
+ || buf[EI_MAG3] != ELFMAG3
+ || (buf[EI_CLASS] != ELFCLASS64 && buf[EI_CLASS] != ELFCLASS32))
+ return ELFCLASSNONE;
+
+ return buf[EI_CLASS];
+}
+
+/* Search /proc/PID/auxv for the AT_SYSINFO_EHDR tag.
+
+ It would be easiest to call get_pid_class and parse everything according to
+ the 32-bit or 64-bit class. But this would bring the overhead of syscalls
+ to open and read the "/proc/%d/exe" file.
+
+ Therefore this function tries to parse the "/proc/%d/auxv" content both
+ ways, as if it were the 32-bit format and also if it were the 64-bit format.
+ Only if it gives some valid data in both cases get_pid_class gets called.
+ In most cases only one of the format bit sizes gives valid data and the
+ get_pid_class call overhead can be saved. */
+
+static int
+grovel_auxv (pid_t pid, Dwfl *dwfl, GElf_Addr *sysinfo_ehdr)
+{
+ char *fname;
+ if (asprintf (&fname, PROCAUXVFMT, pid) < 0)
+ return ENOMEM;
+
+ int fd = open (fname, O_RDONLY);
+ free (fname);
+ if (fd < 0)
+ return errno == ENOENT ? 0 : errno;
+
+ GElf_Addr sysinfo_ehdr64 = 0;
+ GElf_Addr sysinfo_ehdr32 = 0;
+ GElf_Addr segment_align64 = dwfl->segment_align;
+ GElf_Addr segment_align32 = dwfl->segment_align;
+ off_t offset = 0;
+ ssize_t nread;
+ union
+ {
+ Elf64_auxv_t a64[64];
+ Elf32_auxv_t a32[128];
+ } d;
+ do
+ {
+ eu_static_assert (sizeof d.a64 == sizeof d.a32);
+ nread = pread_retry (fd, d.a64, sizeof d.a64, offset);
+ if (nread < 0)
+ {
+ int ret = errno;
+ close (fd);
+ return ret;
+ }
+ for (size_t a32i = 0; a32i < nread / sizeof d.a32[0]; a32i++)
+ {
+ const Elf32_auxv_t *a32 = d.a32 + a32i;
+ switch (a32->a_type)
+ {
+ case AT_SYSINFO_EHDR:
+ sysinfo_ehdr32 = a32->a_un.a_val;
+ break;
+ case AT_PAGESZ:
+ segment_align32 = a32->a_un.a_val;
+ break;
+ }
+ }
+ for (size_t a64i = 0; a64i < nread / sizeof d.a64[0]; a64i++)
+ {
+ const Elf64_auxv_t *a64 = d.a64 + a64i;
+ switch (a64->a_type)
+ {
+ case AT_SYSINFO_EHDR:
+ sysinfo_ehdr64 = a64->a_un.a_val;
+ break;
+ case AT_PAGESZ:
+ segment_align64 = a64->a_un.a_val;
+ break;
+ }
+ }
+ offset += nread;
+ }
+ while (nread == sizeof d.a64);
+
+ close (fd);
+
+ bool valid64 = sysinfo_ehdr64 != 0 || segment_align64 != dwfl->segment_align;
+ bool valid32 = sysinfo_ehdr32 != 0 || segment_align32 != dwfl->segment_align;
+
+ unsigned char pid_class = ELFCLASSNONE;
+ if (valid64 && valid32)
+ pid_class = get_pid_class (pid);
+
+ if (pid_class == ELFCLASS64 || (valid64 && ! valid32))
+ {
+ *sysinfo_ehdr = sysinfo_ehdr64;
+ dwfl->segment_align = segment_align64;
+ return 0;
+ }
+ if (pid_class == ELFCLASS32 || (! valid64 && valid32))
+ {
+ *sysinfo_ehdr = sysinfo_ehdr32;
+ dwfl->segment_align = segment_align32;
+ return 0;
+ }
+ return ENOEXEC;
+}
+
+static inline bool
+do_report (Dwfl *dwfl, char **plast_file, Dwarf_Addr low, Dwarf_Addr high)
+{
+ if (*plast_file != NULL)
+ {
+ Dwfl_Module *mod = INTUSE(dwfl_report_module) (dwfl, *plast_file,
+ low, high);
+ free (*plast_file);
+ *plast_file = NULL;
+ if (unlikely (mod == NULL))
+ return true;
+ }
+ return false;
+}
+
+#define report() do_report(dwfl, &last_file, low, high)
+
+static int
+proc_maps_report (Dwfl *dwfl, FILE *f, GElf_Addr sysinfo_ehdr, pid_t pid)
+{
+ unsigned int last_dmajor = -1, last_dminor = -1;
+ uint64_t last_ino = -1;
+ char *last_file = NULL;
+ Dwarf_Addr low = 0, high = 0;
+
+ char *line = NULL;
+ size_t linesz;
+ ssize_t len;
+ while ((len = getline (&line, &linesz, f)) > 0)
+ {
+ if (line[len - 1] == '\n')
+ line[len - 1] = '\0';
+
+ Dwarf_Addr start, end, offset;
+ unsigned int dmajor, dminor;
+ uint64_t ino;
+ int nread = -1;
+ if (sscanf (line, "%" PRIx64 "-%" PRIx64 " %*s %" PRIx64
+ " %x:%x %" PRIi64 " %n",
+ &start, &end, &offset, &dmajor, &dminor, &ino, &nread) < 6
+ || nread <= 0)
+ {
+ free (line);
+ free (last_file);
+ return ENOEXEC;
+ }
+
+ /* If this is the special mapping AT_SYSINFO_EHDR pointed us at,
+ report the last one and then this special one. */
+ if (start == sysinfo_ehdr && start != 0)
+ {
+ if (report ())
+ {
+ bad_report:
+ free (line);
+ return -1;
+ }
+
+ low = start;
+ high = end;
+ if (asprintf (&last_file, "[vdso: %d]", (int) pid) < 0
+ || report ())
+ goto bad_report;
+ }
+
+ char *file = line + nread + strspn (line + nread, " \t");
+ if (file[0] != '/' || (ino == 0 && dmajor == 0 && dminor == 0))
+ /* This line doesn't indicate a file mapping. */
+ continue;
+
+ if (last_file != NULL
+ && ino == last_ino && dmajor == last_dmajor && dminor == last_dminor)
+ {
+ /* This is another portion of the same file's mapping. */
+ if (strcmp (last_file, file) != 0)
+ {
+ free (last_file);
+ goto bad_report;
+ }
+ high = end;
+ }
+ else
+ {
+ /* This is a different file mapping. Report the last one. */
+ if (report ())
+ goto bad_report;
+ low = start;
+ high = end;
+ last_file = strdup (file);
+ last_ino = ino;
+ last_dmajor = dmajor;
+ last_dminor = dminor;
+ }
+ }
+ free (line);
+
+ int result = ferror_unlocked (f) ? errno : feof_unlocked (f) ? 0 : ENOEXEC;
+
+ /* Report the final one. */
+ bool lose = report ();
+
+ return result != 0 ? result : lose ? -1 : 0;
+}
+
+int
+dwfl_linux_proc_maps_report (Dwfl *dwfl, FILE *f)
+{
+ return proc_maps_report (dwfl, f, 0, 0);
+}
+INTDEF (dwfl_linux_proc_maps_report)
+
+int
+dwfl_linux_proc_report (Dwfl *dwfl, pid_t pid)
+{
+ if (dwfl == NULL)
+ return -1;
+
+ /* We'll notice the AT_SYSINFO_EHDR address specially when we hit it. */
+ GElf_Addr sysinfo_ehdr = 0;
+ int result = grovel_auxv (pid, dwfl, &sysinfo_ehdr);
+ if (result != 0)
+ return result;
+
+ char *fname;
+ if (asprintf (&fname, PROCMAPSFMT, pid) < 0)
+ return ENOMEM;
+
+ FILE *f = fopen (fname, "r");
+ free (fname);
+ if (f == NULL)
+ return errno;
+
+ (void) __fsetlocking (f, FSETLOCKING_BYCALLER);
+
+ result = proc_maps_report (dwfl, f, sysinfo_ehdr, pid);
+
+ fclose (f);
+
+ return result;
+}
+INTDEF (dwfl_linux_proc_report)
+
+static ssize_t
+read_proc_memory (void *arg, void *data, GElf_Addr address,
+ size_t minread, size_t maxread)
+{
+ const int fd = *(const int *) arg;
+
+ /* This code relies on the fact the Linux kernel accepts negative
+ offsets when seeking /dev/$$/mem files, as a special case. In
+ particular pread cannot be used here, because it will always
+ return EINVAL when passed a negative offset. */
+
+ if (lseek (fd, (off_t) address, SEEK_SET) == -1)
+ return -1;
+
+ ssize_t nread = read (fd, data, maxread);
+
+ if (nread > 0 && (size_t) nread < minread)
+ nread = 0;
+ return nread;
+}
+
+extern Elf *elf_from_remote_memory (GElf_Addr ehdr_vma,
+ GElf_Xword pagesize,
+ GElf_Addr *loadbasep,
+ ssize_t (*read_memory) (void *arg,
+ void *data,
+ GElf_Addr address,
+ size_t minread,
+ size_t maxread),
+ void *arg);
+
+
+/* Dwfl_Callbacks.find_elf */
+
+int
+dwfl_linux_proc_find_elf (Dwfl_Module *mod __attribute__ ((unused)),
+ void **userdata __attribute__ ((unused)),
+ const char *module_name, Dwarf_Addr base,
+ char **file_name, Elf **elfp)
+{
+ int pid = -1;
+ if (module_name[0] == '/')
+ {
+ /* When this callback is used together with dwfl_linux_proc_report
+ then we might see mappings of special character devices. Make
+ sure we only open and return regular files. Special devices
+ might hang on open or read. (deleted) files are super special.
+ The image might come from memory if we are attached. */
+ struct stat sb;
+ if (stat (module_name, &sb) == -1 || (sb.st_mode & S_IFMT) != S_IFREG)
+ {
+ if (strcmp (strrchr (module_name, ' ') ?: "", " (deleted)") == 0)
+ pid = INTUSE(dwfl_pid) (mod->dwfl);
+ else
+ return -1;
+ }
+
+ if (pid == -1)
+ {
+ int fd = open (module_name, O_RDONLY);
+ if (fd >= 0)
+ {
+ *file_name = strdup (module_name);
+ if (*file_name == NULL)
+ {
+ close (fd);
+ return ENOMEM;
+ }
+ }
+ return fd;
+ }
+ }
+
+ if (pid != -1 || sscanf (module_name, "[vdso: %d]", &pid) == 1)
+ {
+ /* Special case for in-memory ELF image. */
+
+ bool detach = false;
+ bool tid_was_stopped = false;
+ struct __libdwfl_pid_arg *pid_arg = __libdwfl_get_pid_arg (mod->dwfl);
+ if (pid_arg != NULL && ! pid_arg->assume_ptrace_stopped)
+ {
+ /* If any thread is already attached we are fine. Read
+ through that thread. It doesn't have to be the main
+ thread pid. */
+ pid_t tid = pid_arg->tid_attached;
+ if (tid != 0)
+ pid = tid;
+ else
+ detach = __libdwfl_ptrace_attach (pid, &tid_was_stopped);
+ }
+
+ char *fname;
+ if (asprintf (&fname, PROCMEMFMT, pid) < 0)
+ goto detach;
+
+ int fd = open (fname, O_RDONLY);
+ free (fname);
+ if (fd < 0)
+ goto detach;
+
+ *elfp = elf_from_remote_memory (base, sysconf (_SC_PAGESIZE), NULL,
+ &read_proc_memory, &fd);
+
+ close (fd);
+
+ *file_name = NULL;
+
+ detach:
+ if (detach)
+ __libdwfl_ptrace_detach (pid, tid_was_stopped);
+ return -1;
+ }
+
+ return -1;
+}
+INTDEF (dwfl_linux_proc_find_elf)