#include "observer.h"
#include "objfiles.h"
#include "infcall.h"
-#include "nat/linux-maps.h"
#include "gdbcmd.h"
+#include "gdb_regex.h"
#include <ctype.h>
+/* This enum represents the values that the user can choose when
+ informing the Linux kernel about which memory mappings will be
+ dumped in a corefile. They are described in the file
+ Documentation/filesystems/proc.txt, inside the Linux kernel
+ tree. */
+
+enum filterflags
+ {
+ COREFILTER_ANON_PRIVATE = 1 << 0,
+ COREFILTER_ANON_SHARED = 1 << 1,
+ COREFILTER_MAPPED_PRIVATE = 1 << 2,
+ COREFILTER_MAPPED_SHARED = 1 << 3,
+ COREFILTER_ELF_HEADERS = 1 << 4,
+ COREFILTER_HUGETLB_PRIVATE = 1 << 5,
+ COREFILTER_HUGETLB_SHARED = 1 << 6,
+ };
+
+/* This struct is used to map flags found in the "VmFlags:" field (in
+ the /proc/<PID>/smaps file). */
+
+struct smaps_vmflags
+ {
+ /* Zero if this structure has not been initialized yet. It
+ probably means that the Linux kernel being used does not emit
+ the "VmFlags:" field on "/proc/PID/smaps". */
+
+ unsigned int initialized_p : 1;
+
+ /* Memory mapped I/O area (VM_IO, "io"). */
+
+ unsigned int io_page : 1;
+
+ /* Area uses huge TLB pages (VM_HUGETLB, "ht"). */
+
+ unsigned int uses_huge_tlb : 1;
+
+ /* Do not include this memory region on the coredump (VM_DONTDUMP, "dd"). */
+
+ unsigned int exclude_coredump : 1;
+
+ /* Is this a MAP_SHARED mapping (VM_SHARED, "sh"). */
+
+ unsigned int shared_mapping : 1;
+ };
+
/* Whether to take the /proc/PID/coredump_filter into account when
generating a corefile. */
return normal_pid_to_str (ptid);
}
+/* Service function for corefiles and info proc. */
+
+static void
+read_mapping (const char *line,
+ ULONGEST *addr, ULONGEST *endaddr,
+ const char **permissions, size_t *permissions_len,
+ ULONGEST *offset,
+ const char **device, size_t *device_len,
+ ULONGEST *inode,
+ const char **filename)
+{
+ const char *p = line;
+
+ *addr = strtoulst (p, &p, 16);
+ if (*p == '-')
+ p++;
+ *endaddr = strtoulst (p, &p, 16);
+
+ p = skip_spaces_const (p);
+ *permissions = p;
+ while (*p && !isspace (*p))
+ p++;
+ *permissions_len = p - *permissions;
+
+ *offset = strtoulst (p, &p, 16);
+
+ p = skip_spaces_const (p);
+ *device = p;
+ while (*p && !isspace (*p))
+ p++;
+ *device_len = p - *device;
+
+ *inode = strtoulst (p, &p, 10);
+
+ p = skip_spaces_const (p);
+ *filename = p;
+}
+
+/* Helper function to decode the "VmFlags" field in /proc/PID/smaps.
+
+ This function was based on the documentation found on
+ <Documentation/filesystems/proc.txt>, on the Linux kernel.
+
+ Linux kernels before commit
+ 834f82e2aa9a8ede94b17b656329f850c1471514 (3.10) do not have this
+ field on smaps. */
+
+static void
+decode_vmflags (char *p, struct smaps_vmflags *v)
+{
+ char *saveptr = NULL;
+ const char *s;
+
+ v->initialized_p = 1;
+ p = skip_to_space (p);
+ p = skip_spaces (p);
+
+ for (s = strtok_r (p, " ", &saveptr);
+ s != NULL;
+ s = strtok_r (NULL, " ", &saveptr))
+ {
+ if (strcmp (s, "io") == 0)
+ v->io_page = 1;
+ else if (strcmp (s, "ht") == 0)
+ v->uses_huge_tlb = 1;
+ else if (strcmp (s, "dd") == 0)
+ v->exclude_coredump = 1;
+ else if (strcmp (s, "sh") == 0)
+ v->shared_mapping = 1;
+ }
+}
+
+/* Return 1 if the memory mapping is anonymous, 0 otherwise.
+
+ FILENAME is the name of the file present in the first line of the
+ memory mapping, in the "/proc/PID/smaps" output. For example, if
+ the first line is:
+
+ 7fd0ca877000-7fd0d0da0000 r--p 00000000 fd:02 2100770 /path/to/file
+
+ Then FILENAME will be "/path/to/file". */
+
+static int
+mapping_is_anonymous_p (const char *filename)
+{
+ static regex_t dev_zero_regex, shmem_file_regex, file_deleted_regex;
+ static int init_regex_p = 0;
+
+ if (!init_regex_p)
+ {
+ struct cleanup *c = make_cleanup (null_cleanup, NULL);
+
+ /* Let's be pessimistic and assume there will be an error while
+ compiling the regex'es. */
+ init_regex_p = -1;
+
+ /* DEV_ZERO_REGEX matches "/dev/zero" filenames (with or
+ without the "(deleted)" string in the end). We know for
+ sure, based on the Linux kernel code, that memory mappings
+ whose associated filename is "/dev/zero" are guaranteed to be
+ MAP_ANONYMOUS. */
+ compile_rx_or_error (&dev_zero_regex, "^/dev/zero\\( (deleted)\\)\\?$",
+ _("Could not compile regex to match /dev/zero "
+ "filename"));
+ /* SHMEM_FILE_REGEX matches "/SYSV%08x" filenames (with or
+ without the "(deleted)" string in the end). These filenames
+ refer to shared memory (shmem), and memory mappings
+ associated with them are MAP_ANONYMOUS as well. */
+ compile_rx_or_error (&shmem_file_regex,
+ "^/\\?SYSV[0-9a-fA-F]\\{8\\}\\( (deleted)\\)\\?$",
+ _("Could not compile regex to match shmem "
+ "filenames"));
+ /* FILE_DELETED_REGEX is a heuristic we use to try to mimic the
+ Linux kernel's 'n_link == 0' code, which is responsible to
+ decide if it is dealing with a 'MAP_SHARED | MAP_ANONYMOUS'
+ mapping. In other words, if FILE_DELETED_REGEX matches, it
+ does not necessarily mean that we are dealing with an
+ anonymous shared mapping. However, there is no easy way to
+ detect this currently, so this is the best approximation we
+ have.
+
+ As a result, GDB will dump readonly pages of deleted
+ executables when using the default value of coredump_filter
+ (0x33), while the Linux kernel will not dump those pages.
+ But we can live with that. */
+ compile_rx_or_error (&file_deleted_regex, " (deleted)$",
+ _("Could not compile regex to match "
+ "'<file> (deleted)'"));
+ /* We will never release these regexes, so just discard the
+ cleanups. */
+ discard_cleanups (c);
+
+ /* If we reached this point, then everything succeeded. */
+ init_regex_p = 1;
+ }
+
+ if (init_regex_p == -1)
+ {
+ const char deleted[] = " (deleted)";
+ size_t del_len = sizeof (deleted) - 1;
+ size_t filename_len = strlen (filename);
+
+ /* There was an error while compiling the regex'es above. In
+ order to try to give some reliable information to the caller,
+ we just try to find the string " (deleted)" in the filename.
+ If we managed to find it, then we assume the mapping is
+ anonymous. */
+ return (filename_len >= del_len
+ && strcmp (filename + filename_len - del_len, deleted) == 0);
+ }
+
+ if (*filename == '\0'
+ || regexec (&dev_zero_regex, filename, 0, NULL, 0) == 0
+ || regexec (&shmem_file_regex, filename, 0, NULL, 0) == 0
+ || regexec (&file_deleted_regex, filename, 0, NULL, 0) == 0)
+ return 1;
+
+ return 0;
+}
+
+/* Return 0 if the memory mapping (which is related to FILTERFLAGS, V,
+ MAYBE_PRIVATE_P, and MAPPING_ANONYMOUS_P) should not be dumped, or
+ greater than 0 if it should.
+
+ In a nutshell, this is the logic that we follow in order to decide
+ if a mapping should be dumped or not.
+
+ - If the mapping is associated to a file whose name ends with
+ " (deleted)", or if the file is "/dev/zero", or if it is
+ "/SYSV%08x" (shared memory), or if there is no file associated
+ with it, or if the AnonHugePages: or the Anonymous: fields in the
+ /proc/PID/smaps have contents, then GDB considers this mapping to
+ be anonymous. Otherwise, GDB considers this mapping to be a
+ file-backed mapping (because there will be a file associated with
+ it).
+
+ It is worth mentioning that, from all those checks described
+ above, the most fragile is the one to see if the file name ends
+ with " (deleted)". This does not necessarily mean that the
+ mapping is anonymous, because the deleted file associated with
+ the mapping may have been a hard link to another file, for
+ example. The Linux kernel checks to see if "i_nlink == 0", but
+ GDB cannot easily (and normally) do this check (iff running as
+ root, it could find the mapping in /proc/PID/map_files/ and
+ determine whether there still are other hard links to the
+ inode/file). Therefore, we made a compromise here, and we assume
+ that if the file name ends with " (deleted)", then the mapping is
+ indeed anonymous. FWIW, this is something the Linux kernel could
+ do better: expose this information in a more direct way.
+
+ - If we see the flag "sh" in the "VmFlags:" field (in
+ /proc/PID/smaps), then certainly the memory mapping is shared
+ (VM_SHARED). If we have access to the VmFlags, and we don't see
+ the "sh" there, then certainly the mapping is private. However,
+ Linux kernels before commit
+ 834f82e2aa9a8ede94b17b656329f850c1471514 (3.10) do not have the
+ "VmFlags:" field; in that case, we use another heuristic: if we
+ see 'p' in the permission flags, then we assume that the mapping
+ is private, even though the presence of the 's' flag there would
+ mean VM_MAYSHARE, which means the mapping could still be private.
+ This should work OK enough, however. */
+
+static int
+dump_mapping_p (enum filterflags filterflags, const struct smaps_vmflags *v,
+ int maybe_private_p, int mapping_anon_p, int mapping_file_p,
+ const char *filename)
+{
+ /* Initially, we trust in what we received from our caller. This
+ value may not be very precise (i.e., it was probably gathered
+ from the permission line in the /proc/PID/smaps list, which
+ actually refers to VM_MAYSHARE, and not VM_SHARED), but it is
+ what we have until we take a look at the "VmFlags:" field
+ (assuming that the version of the Linux kernel being used
+ supports it, of course). */
+ int private_p = maybe_private_p;
+
+ /* We always dump vDSO and vsyscall mappings, because it's likely that
+ there'll be no file to read the contents from at core load time.
+ The kernel does the same. */
+ if (strcmp ("[vdso]", filename) == 0
+ || strcmp ("[vsyscall]", filename) == 0)
+ return 1;
+
+ if (v->initialized_p)
+ {
+ /* We never dump I/O mappings. */
+ if (v->io_page)
+ return 0;
+
+ /* Check if we should exclude this mapping. */
+ if (v->exclude_coredump)
+ return 0;
+
+ /* Update our notion of whether this mapping is shared or
+ private based on a trustworthy value. */
+ private_p = !v->shared_mapping;
+
+ /* HugeTLB checking. */
+ if (v->uses_huge_tlb)
+ {
+ if ((private_p && (filterflags & COREFILTER_HUGETLB_PRIVATE))
+ || (!private_p && (filterflags & COREFILTER_HUGETLB_SHARED)))
+ return 1;
+
+ return 0;
+ }
+ }
+
+ if (private_p)
+ {
+ if (mapping_anon_p && mapping_file_p)
+ {
+ /* This is a special situation. It can happen when we see a
+ mapping that is file-backed, but that contains anonymous
+ pages. */
+ return ((filterflags & COREFILTER_ANON_PRIVATE) != 0
+ || (filterflags & COREFILTER_MAPPED_PRIVATE) != 0);
+ }
+ else if (mapping_anon_p)
+ return (filterflags & COREFILTER_ANON_PRIVATE) != 0;
+ else
+ return (filterflags & COREFILTER_MAPPED_PRIVATE) != 0;
+ }
+ else
+ {
+ if (mapping_anon_p && mapping_file_p)
+ {
+ /* This is a special situation. It can happen when we see a
+ mapping that is file-backed, but that contains anonymous
+ pages. */
+ return ((filterflags & COREFILTER_ANON_SHARED) != 0
+ || (filterflags & COREFILTER_MAPPED_SHARED) != 0);
+ }
+ else if (mapping_anon_p)
+ return (filterflags & COREFILTER_ANON_SHARED) != 0;
+ else
+ return (filterflags & COREFILTER_MAPPED_SHARED) != 0;
+ }
+}
+
/* Implement the "info proc" command. */
static void
error (_("unable to handle request"));
}
-/* A structure for passing information through
- linux_find_memory_regions_full. */
-
-struct linux_find_memory_regions_data
-{
- /* The original callback. */
-
- find_memory_region_ftype func;
-
- /* The original datum. */
-
- void *data;
-};
-
-/* A callback for linux_find_memory_regions that converts between the
- "full"-style callback and find_memory_region_ftype. */
-
-static int
-linux_find_memory_regions_thunk (ULONGEST vaddr, ULONGEST size,
- ULONGEST offset, ULONGEST inode,
- int read, int write, int exec, int modified,
- const char *filename, void *arg)
-{
- struct linux_find_memory_regions_data *data = arg;
-
- return data->func (vaddr, size, read, write, exec, modified, data->data);
-}
+typedef int linux_find_memory_region_ftype (ULONGEST vaddr, ULONGEST size,
+ ULONGEST offset, ULONGEST inode,
+ int read, int write,
+ int exec, int modified,
+ const char *filename,
+ void *data);
-/* Wrapper of linux_find_memory_regions_full handling FAKE_PID_P in GDB. */
+/* List memory regions in the inferior for a corefile. */
static int
-linux_find_memory_regions_gdb (struct gdbarch *gdbarch,
- linux_find_memory_region_ftype *func,
- void *func_data)
+linux_find_memory_regions_full (struct gdbarch *gdbarch,
+ linux_find_memory_region_ftype *func,
+ void *obfd)
{
+ char mapsfilename[100];
+ char coredumpfilter_name[100];
+ char *data, *coredumpfilterdata;
pid_t pid;
/* Default dump behavior of coredump_filter (0x33), according to
Documentation/filesystems/proc.txt from the Linux kernel
| COREFILTER_ELF_HEADERS
| COREFILTER_HUGETLB_PRIVATE);
- /* We need to know the real target PID so
- linux_find_memory_regions_full can access /proc. */
+ /* We need to know the real target PID to access /proc. */
if (current_inferior ()->fake_pid_p)
- return -1;
+ return 1;
pid = current_inferior ()->pid;
if (use_coredump_filter)
{
- char coredumpfilter_name[100], *coredumpfilterdata;
-
xsnprintf (coredumpfilter_name, sizeof (coredumpfilter_name),
"/proc/%d/coredump_filter", pid);
coredumpfilterdata = target_fileio_read_stralloc (NULL,
}
}
- return linux_find_memory_regions_full (pid, filterflags, func, func_data);
+ xsnprintf (mapsfilename, sizeof mapsfilename, "/proc/%d/smaps", pid);
+ data = target_fileio_read_stralloc (NULL, mapsfilename);
+ if (data == NULL)
+ {
+ /* Older Linux kernels did not support /proc/PID/smaps. */
+ xsnprintf (mapsfilename, sizeof mapsfilename, "/proc/%d/maps", pid);
+ data = target_fileio_read_stralloc (NULL, mapsfilename);
+ }
+
+ if (data != NULL)
+ {
+ struct cleanup *cleanup = make_cleanup (xfree, data);
+ char *line, *t;
+
+ line = strtok_r (data, "\n", &t);
+ while (line != NULL)
+ {
+ ULONGEST addr, endaddr, offset, inode;
+ const char *permissions, *device, *filename;
+ struct smaps_vmflags v;
+ size_t permissions_len, device_len;
+ int read, write, exec, priv;
+ int has_anonymous = 0;
+ int should_dump_p = 0;
+ int mapping_anon_p;
+ int mapping_file_p;
+
+ memset (&v, 0, sizeof (v));
+ read_mapping (line, &addr, &endaddr, &permissions, &permissions_len,
+ &offset, &device, &device_len, &inode, &filename);
+ mapping_anon_p = mapping_is_anonymous_p (filename);
+ /* If the mapping is not anonymous, then we can consider it
+ to be file-backed. These two states (anonymous or
+ file-backed) seem to be exclusive, but they can actually
+ coexist. For example, if a file-backed mapping has
+ "Anonymous:" pages (see more below), then the Linux
+ kernel will dump this mapping when the user specified
+ that she only wants anonymous mappings in the corefile
+ (*even* when she explicitly disabled the dumping of
+ file-backed mappings). */
+ mapping_file_p = !mapping_anon_p;
+
+ /* Decode permissions. */
+ read = (memchr (permissions, 'r', permissions_len) != 0);
+ write = (memchr (permissions, 'w', permissions_len) != 0);
+ exec = (memchr (permissions, 'x', permissions_len) != 0);
+ /* 'private' here actually means VM_MAYSHARE, and not
+ VM_SHARED. In order to know if a mapping is really
+ private or not, we must check the flag "sh" in the
+ VmFlags field. This is done by decode_vmflags. However,
+ if we are using a Linux kernel released before the commit
+ 834f82e2aa9a8ede94b17b656329f850c1471514 (3.10), we will
+ not have the VmFlags there. In this case, there is
+ really no way to know if we are dealing with VM_SHARED,
+ so we just assume that VM_MAYSHARE is enough. */
+ priv = memchr (permissions, 'p', permissions_len) != 0;
+
+ /* Try to detect if region should be dumped by parsing smaps
+ counters. */
+ for (line = strtok_r (NULL, "\n", &t);
+ line != NULL && line[0] >= 'A' && line[0] <= 'Z';
+ line = strtok_r (NULL, "\n", &t))
+ {
+ char keyword[64 + 1];
+
+ if (sscanf (line, "%64s", keyword) != 1)
+ {
+ warning (_("Error parsing {s,}maps file '%s'"), mapsfilename);
+ break;
+ }
+
+ if (strcmp (keyword, "Anonymous:") == 0)
+ {
+ /* Older Linux kernels did not support the
+ "Anonymous:" counter. Check it here. */
+ has_anonymous = 1;
+ }
+ else if (strcmp (keyword, "VmFlags:") == 0)
+ decode_vmflags (line, &v);
+
+ if (strcmp (keyword, "AnonHugePages:") == 0
+ || strcmp (keyword, "Anonymous:") == 0)
+ {
+ unsigned long number;
+
+ if (sscanf (line, "%*s%lu", &number) != 1)
+ {
+ warning (_("Error parsing {s,}maps file '%s' number"),
+ mapsfilename);
+ break;
+ }
+ if (number > 0)
+ {
+ /* Even if we are dealing with a file-backed
+ mapping, if it contains anonymous pages we
+ consider it to be *also* an anonymous
+ mapping, because this is what the Linux
+ kernel does:
+
+ // Dump segments that have been written to.
+ if (vma->anon_vma && FILTER(ANON_PRIVATE))
+ goto whole;
+
+ Note that if the mapping is already marked as
+ file-backed (i.e., mapping_file_p is
+ non-zero), then this is a special case, and
+ this mapping will be dumped either when the
+ user wants to dump file-backed *or* anonymous
+ mappings. */
+ mapping_anon_p = 1;
+ }
+ }
+ }
+
+ if (has_anonymous)
+ should_dump_p = dump_mapping_p (filterflags, &v, priv,
+ mapping_anon_p, mapping_file_p,
+ filename);
+ else
+ {
+ /* Older Linux kernels did not support the "Anonymous:" counter.
+ If it is missing, we can't be sure - dump all the pages. */
+ should_dump_p = 1;
+ }
+
+ /* Invoke the callback function to create the corefile segment. */
+ if (should_dump_p)
+ func (addr, endaddr - addr, offset, inode,
+ read, write, exec, 1, /* MODIFIED is true because we
+ want to dump the mapping. */
+ filename, obfd);
+ }
+
+ do_cleanups (cleanup);
+ return 0;
+ }
+
+ return 1;
+}
+
+/* A structure for passing information through
+ linux_find_memory_regions_full. */
+
+struct linux_find_memory_regions_data
+{
+ /* The original callback. */
+
+ find_memory_region_ftype func;
+
+ /* The original datum. */
+
+ void *obfd;
+};
+
+/* A callback for linux_find_memory_regions that converts between the
+ "full"-style callback and find_memory_region_ftype. */
+
+static int
+linux_find_memory_regions_thunk (ULONGEST vaddr, ULONGEST size,
+ ULONGEST offset, ULONGEST inode,
+ int read, int write, int exec, int modified,
+ const char *filename, void *arg)
+{
+ struct linux_find_memory_regions_data *data = arg;
+
+ return data->func (vaddr, size, read, write, exec, modified, data->obfd);
}
/* A variant of linux_find_memory_regions_full that is suitable as the
static int
linux_find_memory_regions (struct gdbarch *gdbarch,
- find_memory_region_ftype func, void *func_data)
+ find_memory_region_ftype func, void *obfd)
{
struct linux_find_memory_regions_data data;
data.func = func;
- data.data = func_data;
+ data.obfd = obfd;
- return linux_find_memory_regions_gdb (gdbarch,
- linux_find_memory_regions_thunk, &data);
+ return linux_find_memory_regions_full (gdbarch,
+ linux_find_memory_regions_thunk,
+ &data);
}
/* Determine which signal stopped execution. */
pack_long (buf, long_type, 1);
obstack_grow (&data_obstack, buf, TYPE_LENGTH (long_type));
- linux_find_memory_regions_gdb (gdbarch, linux_make_mappings_callback,
- &mapping_data);
+ linux_find_memory_regions_full (gdbarch, linux_make_mappings_callback,
+ &mapping_data);
if (mapping_data.file_count != 0)
{
projects / deliverable / binutils-gdb.git / blobdiff