Refactor parsing of /proc/<pid>/smaps
The Linux kernel exposes the information about MTE-protected pages via the proc filesystem, more specifically through the smaps file. What we're looking for is a mapping with the 'mt' flag, which tells us that mapping was created with a PROT_MTE flag and, thus, is capable of using memory tagging. We already parse that file for other purposes (core file generation/filtering), so this patch refactors the code to make the parsing of the smaps file reusable for memory tagging. The function linux_address_in_memtag_page uses the refactored code to allow querying for memory tag support in a particular address, and it gets used in the next patch. gdb/ChangeLog: 2021-03-24 Luis Machado <luis.machado@linaro.org> * linux-tdep.c (struct smaps_vmflags) <memory_tagging>: New flag bit. (struct smaps_data): New struct. (decode_vmflags): Handle the 'mt' flag. (parse_smaps_data): New function, refactored from linux_find_memory_regions_full. (linux_address_in_memtag_page): New function. (linux_find_memory_regions_full): Refactor into parse_smaps_data. * linux-tdep.h (linux_address_in_memtag_page): New prototype.
This commit is contained in:
Luis Machado
parent
93e447c605
commit
1e735120b9
3 changed files with 251 additions and 122 deletions
|
|
@ -1,3 +1,15 @@
|
|||
2021-03-24 Luis Machado <luis.machado@linaro.org>
|
||||
|
||||
* linux-tdep.c (struct smaps_vmflags) <memory_tagging>: New flag
|
||||
bit.
|
||||
(struct smaps_data): New struct.
|
||||
(decode_vmflags): Handle the 'mt' flag.
|
||||
(parse_smaps_data): New function, refactored from
|
||||
linux_find_memory_regions_full.
|
||||
(linux_address_in_memtag_page): New function.
|
||||
(linux_find_memory_regions_full): Refactor into parse_smaps_data.
|
||||
* linux-tdep.h (linux_address_in_memtag_page): New prototype.
|
||||
|
||||
2021-03-24 Luis Machado <luis.machado@linaro.org>
|
||||
|
||||
* linux-tdep.c (linux_find_memory_regions_full): Use std::string
|
||||
|
|
|
|||
357
gdb/linux-tdep.c
357
gdb/linux-tdep.c
|
|
@ -88,8 +88,33 @@ struct smaps_vmflags
|
|||
/* Is this a MAP_SHARED mapping (VM_SHARED, "sh"). */
|
||||
|
||||
unsigned int shared_mapping : 1;
|
||||
|
||||
/* Memory map has memory tagging enabled. */
|
||||
|
||||
unsigned int memory_tagging : 1;
|
||||
};
|
||||
|
||||
/* Data structure that holds the information contained in the
|
||||
/proc/<pid>/smaps file. */
|
||||
|
||||
struct smaps_data
|
||||
{
|
||||
ULONGEST start_address;
|
||||
ULONGEST end_address;
|
||||
std::string filename;
|
||||
struct smaps_vmflags vmflags;
|
||||
bool read;
|
||||
bool write;
|
||||
bool exec;
|
||||
bool priv;
|
||||
bool has_anonymous;
|
||||
bool mapping_anon_p;
|
||||
bool mapping_file_p;
|
||||
|
||||
ULONGEST inode;
|
||||
ULONGEST offset;
|
||||
};
|
||||
|
||||
/* Whether to take the /proc/PID/coredump_filter into account when
|
||||
generating a corefile. */
|
||||
|
||||
|
|
@ -476,6 +501,8 @@ decode_vmflags (char *p, struct smaps_vmflags *v)
|
|||
v->exclude_coredump = 1;
|
||||
else if (strcmp (s, "sh") == 0)
|
||||
v->shared_mapping = 1;
|
||||
else if (strcmp (s, "mt") == 0)
|
||||
v->memory_tagging = 1;
|
||||
}
|
||||
}
|
||||
|
||||
|
|
@ -1271,6 +1298,180 @@ typedef int linux_dump_mapping_p_ftype (filter_flags filterflags,
|
|||
ULONGEST addr,
|
||||
ULONGEST offset);
|
||||
|
||||
/* Helper function to parse the contents of /proc/<pid>/smaps into a data
|
||||
structure, for easy access.
|
||||
|
||||
DATA is the contents of the smaps file. The parsed contents are stored
|
||||
into the SMAPS vector. */
|
||||
|
||||
static std::vector<struct smaps_data>
|
||||
parse_smaps_data (const char *data,
|
||||
const std::string maps_filename)
|
||||
{
|
||||
char *line, *t;
|
||||
|
||||
gdb_assert (data != nullptr);
|
||||
|
||||
line = strtok_r ((char *) data, "\n", &t);
|
||||
|
||||
std::vector<struct smaps_data> smaps;
|
||||
|
||||
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 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'"),
|
||||
maps_filename.c_str ());
|
||||
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"),
|
||||
maps_filename.c_str ());
|
||||
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;
|
||||
}
|
||||
}
|
||||
}
|
||||
/* Save the smaps entry to the vector. */
|
||||
struct smaps_data map;
|
||||
|
||||
map.start_address = addr;
|
||||
map.end_address = endaddr;
|
||||
map.filename = filename;
|
||||
map.vmflags = v;
|
||||
map.read = read? true : false;
|
||||
map.write = write? true : false;
|
||||
map.exec = exec? true : false;
|
||||
map.priv = priv? true : false;
|
||||
map.has_anonymous = has_anonymous;
|
||||
map.mapping_anon_p = mapping_anon_p? true : false;
|
||||
map.mapping_file_p = mapping_file_p? true : false;
|
||||
map.offset = offset;
|
||||
map.inode = inode;
|
||||
|
||||
smaps.emplace_back (map);
|
||||
}
|
||||
|
||||
return smaps;
|
||||
}
|
||||
|
||||
/* See linux-tdep.h. */
|
||||
|
||||
bool
|
||||
linux_address_in_memtag_page (CORE_ADDR address)
|
||||
{
|
||||
if (current_inferior ()->fake_pid_p)
|
||||
return false;
|
||||
|
||||
pid_t pid = current_inferior ()->pid;
|
||||
|
||||
std::string smaps_file = string_printf ("/proc/%d/smaps", pid);
|
||||
|
||||
gdb::unique_xmalloc_ptr<char> data
|
||||
= target_fileio_read_stralloc (NULL, smaps_file.c_str ());
|
||||
|
||||
if (data == nullptr)
|
||||
return false;
|
||||
|
||||
/* Parse the contents of smaps into a vector. */
|
||||
std::vector<struct smaps_data> smaps
|
||||
= parse_smaps_data (data.get (), smaps_file);
|
||||
|
||||
for (const smaps_data &map : smaps)
|
||||
{
|
||||
/* Is the address within [start_address, end_address) in a page
|
||||
mapped with memory tagging? */
|
||||
if (address >= map.start_address
|
||||
&& address < map.end_address
|
||||
&& map.vmflags.memory_tagging)
|
||||
return true;
|
||||
}
|
||||
|
||||
return false;
|
||||
}
|
||||
|
||||
/* List memory regions in the inferior for a corefile. */
|
||||
|
||||
static int
|
||||
|
|
@ -1321,137 +1522,49 @@ linux_find_memory_regions_full (struct gdbarch *gdbarch,
|
|||
/* Older Linux kernels did not support /proc/PID/smaps. */
|
||||
maps_filename = string_printf ("/proc/%d/maps", pid);
|
||||
data = target_fileio_read_stralloc (NULL, maps_filename.c_str ());
|
||||
|
||||
if (data == nullptr)
|
||||
return 1;
|
||||
}
|
||||
|
||||
if (data != NULL)
|
||||
/* Parse the contents of smaps into a vector. */
|
||||
std::vector<struct smaps_data> smaps
|
||||
= parse_smaps_data (data.get (), maps_filename.c_str ());
|
||||
|
||||
for (const struct smaps_data &map : smaps)
|
||||
{
|
||||
char *line, *t;
|
||||
int should_dump_p = 0;
|
||||
|
||||
line = strtok_r (data.get (), "\n", &t);
|
||||
while (line != NULL)
|
||||
if (map.has_anonymous)
|
||||
{
|
||||
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'"),
|
||||
maps_filename.c_str ());
|
||||
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"),
|
||||
maps_filename.c_str ());
|
||||
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 = should_dump_mapping_p (filterflags, &v, priv,
|
||||
mapping_anon_p,
|
||||
mapping_file_p,
|
||||
filename, addr, offset);
|
||||
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);
|
||||
should_dump_p
|
||||
= should_dump_mapping_p (filterflags, &map.vmflags,
|
||||
map.priv,
|
||||
map.mapping_anon_p,
|
||||
map.mapping_file_p,
|
||||
map.filename.c_str (),
|
||||
map.start_address,
|
||||
map.offset);
|
||||
}
|
||||
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;
|
||||
}
|
||||
|
||||
return 0;
|
||||
/* Invoke the callback function to create the corefile segment. */
|
||||
if (should_dump_p)
|
||||
{
|
||||
func (map.start_address, map.end_address - map.start_address,
|
||||
map.offset, map.inode, map.read, map.write, map.exec,
|
||||
1, /* MODIFIED is true because we want to dump
|
||||
the mapping. */
|
||||
map.filename.c_str (), obfd);
|
||||
}
|
||||
}
|
||||
|
||||
return 1;
|
||||
return 0;
|
||||
}
|
||||
|
||||
/* A structure for passing information through
|
||||
|
|
|
|||
|
|
@ -43,6 +43,10 @@ DEF_ENUM_FLAGS_TYPE (enum linux_siginfo_extra_field_values,
|
|||
struct type *linux_get_siginfo_type_with_fields (struct gdbarch *gdbarch,
|
||||
linux_siginfo_extra_fields);
|
||||
|
||||
/* Return true if ADDRESS is within the boundaries of a page mapped with
|
||||
memory tagging protection. */
|
||||
bool linux_address_in_memtag_page (CORE_ADDR address);
|
||||
|
||||
typedef char *(*linux_collect_thread_registers_ftype) (const struct regcache *,
|
||||
ptid_t,
|
||||
bfd *, char *, int *,
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue