From: "H.J. Lu" <hjl.tools@gmail.com>
To: GDB <gdb-patches@sourceware.org>
Subject: [PATCH v2] Support glibc multiple namespace extension
Date: Fri, 1 Oct 2021 17:11:16 -0700 [thread overview]
Message-ID: <YVejpFF7xS/yypv+@gmail.com> (raw)
Changes in v2:
1. Don't check shared libraries in other namespaces when updating shared
libraries in a new namespace.
H.J.
---
In glibc, the r_debug structure contains (amongst others) the following
fields:
int r_version:
Version number for this protocol. It should be greater than 0.
If r_version is 2, struct r_debug is extended to struct r_debug_extended
with one additional field:
struct r_debug_extended *r_next;
Link to the next r_debug_extended structure. Each r_debug_extended
structure represents a different namespace. The first r_debug_extended
structure is for the default namespace.
1. Change solib_svr4_r_map argument to take the debug base.
2. Add solib_svr4_r_next to find the link map in the next namespace from
the r_next field.
3. Update svr4_current_sos_direct to get the link map in the next namespace
from the r_next field.
4. Don't check shared libraries in other namespaces when updating shared
libraries in a new namespace.
This fixes PR 11839.
---
gdb/linux-tdep.c | 2 +
gdb/mips-fbsd-tdep.c | 2 +
gdb/mips-netbsd-tdep.c | 2 +
gdb/solib-svr4.c | 78 ++++++++++---
gdb/solib-svr4.h | 3 +
gdbserver/linux-low.cc | 254 +++++++++++++++++++++++++----------------
6 files changed, 227 insertions(+), 114 deletions(-)
diff --git a/gdb/linux-tdep.c b/gdb/linux-tdep.c
index ae2f7c14f6d..a3b20070adc 100644
--- a/gdb/linux-tdep.c
+++ b/gdb/linux-tdep.c
@@ -2744,6 +2744,7 @@ linux_ilp32_fetch_link_map_offsets ()
lmo.r_map_offset = 4;
lmo.r_brk_offset = 8;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = 20;
/* Everything we need is in the first 20 bytes. */
lmo.link_map_size = 20;
@@ -2772,6 +2773,7 @@ linux_lp64_fetch_link_map_offsets ()
lmo.r_map_offset = 8;
lmo.r_brk_offset = 16;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = 40;
/* Everything we need is in the first 40 bytes. */
lmo.link_map_size = 40;
diff --git a/gdb/mips-fbsd-tdep.c b/gdb/mips-fbsd-tdep.c
index 0b7c97c445f..00e38a8f1c4 100644
--- a/gdb/mips-fbsd-tdep.c
+++ b/gdb/mips-fbsd-tdep.c
@@ -495,6 +495,7 @@ mips_fbsd_ilp32_fetch_link_map_offsets (void)
lmo.r_map_offset = 4;
lmo.r_brk_offset = 8;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = -1;
lmo.link_map_size = 24;
lmo.l_addr_offset = 0;
@@ -522,6 +523,7 @@ mips_fbsd_lp64_fetch_link_map_offsets (void)
lmo.r_map_offset = 8;
lmo.r_brk_offset = 16;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = -1;
lmo.link_map_size = 48;
lmo.l_addr_offset = 0;
diff --git a/gdb/mips-netbsd-tdep.c b/gdb/mips-netbsd-tdep.c
index a32ae5e3a29..12d702ef359 100644
--- a/gdb/mips-netbsd-tdep.c
+++ b/gdb/mips-netbsd-tdep.c
@@ -308,6 +308,7 @@ mipsnbsd_ilp32_fetch_link_map_offsets (void)
lmo.r_map_offset = 4;
lmo.r_brk_offset = 8;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = -1;
/* Everything we need is in the first 24 bytes. */
lmo.link_map_size = 24;
@@ -336,6 +337,7 @@ mipsnbsd_lp64_fetch_link_map_offsets (void)
lmo.r_map_offset = 8;
lmo.r_brk_offset = 16;
lmo.r_ldsomap_offset = -1;
+ lmo.r_next_offset = -1;
/* Everything we need is in the first 40 bytes. */
lmo.link_map_size = 48;
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index 3de1bb9c7f7..9d851ba8930 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -767,7 +767,7 @@ locate_base (struct svr4_info *info)
RT_CONSISTENT. */
static CORE_ADDR
-solib_svr4_r_map (struct svr4_info *info)
+solib_svr4_r_map (CORE_ADDR debug_base)
{
struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
@@ -775,7 +775,7 @@ solib_svr4_r_map (struct svr4_info *info)
try
{
- addr = read_memory_typed_address (info->debug_base + lmo->r_map_offset,
+ addr = read_memory_typed_address (debug_base + lmo->r_map_offset,
ptr_type);
}
catch (const gdb_exception_error &ex)
@@ -829,6 +829,37 @@ solib_svr4_r_ldsomap (struct svr4_info *info)
ptr_type);
}
+/* Find the next namespace from the r_next field. */
+
+static CORE_ADDR
+solib_svr4_r_next (CORE_ADDR debug_base)
+{
+ struct link_map_offsets *lmo = svr4_fetch_link_map_offsets ();
+ struct type *ptr_type = builtin_type (target_gdbarch ())->builtin_data_ptr;
+ enum bfd_endian byte_order = type_byte_order (ptr_type);
+ ULONGEST version = 0;
+
+ try
+ {
+ /* Check version, and return zero if `struct r_debug' doesn't have
+ the r_next member. */
+ version
+ = read_memory_unsigned_integer (debug_base + lmo->r_version_offset,
+ lmo->r_version_size, byte_order);
+ }
+ catch (const gdb_exception_error &ex)
+ {
+ exception_print (gdb_stderr, ex);
+ }
+
+ /* The r_next field is added with r_version == 2. */
+ if (version < 2 || lmo->r_next_offset == -1)
+ return 0;
+
+ return read_memory_typed_address (debug_base + lmo->r_next_offset,
+ ptr_type);
+}
+
/* On Solaris systems with some versions of the dynamic linker,
ld.so's l_name pointer points to the SONAME in the string table
rather than into writable memory. So that GDB can find shared
@@ -886,7 +917,7 @@ open_symbol_file_object (int from_tty)
return 0; /* failed somehow... */
/* First link map member should be the executable. */
- lm = solib_svr4_r_map (info);
+ lm = solib_svr4_r_map (info->debug_base);
if (lm == 0)
return 0; /* failed somehow... */
@@ -1323,7 +1354,7 @@ svr4_current_sos_direct (struct svr4_info *info)
/* Walk the inferior's link map list, and build our list of
`struct so_list' nodes. */
- lm = solib_svr4_r_map (info);
+ lm = solib_svr4_r_map (info->debug_base);
if (lm)
svr4_read_so_list (info, lm, 0, &link_ptr, ignore_first);
@@ -1335,6 +1366,18 @@ svr4_current_sos_direct (struct svr4_info *info)
if (lm)
svr4_read_so_list (info, lm, 0, &link_ptr, 0);
+ /* Get the next namespace from the r_next field. */
+ lm = solib_svr4_r_next (info->debug_base);
+ while (lm)
+ {
+ /* Get the link map in this namespace. */
+ CORE_ADDR link_map = solib_svr4_r_map (lm);
+ if (link_map)
+ svr4_read_so_list (info, link_map, 0, &link_ptr, 0);
+ /* Go to the next namespace. */
+ lm = solib_svr4_r_next (lm);
+ }
+
cleanup.release ();
if (head == NULL)
@@ -1706,7 +1749,8 @@ solist_update_full (struct svr4_info *info)
failure. */
static int
-solist_update_incremental (struct svr4_info *info, CORE_ADDR lm)
+solist_update_incremental (struct svr4_info *info, CORE_ADDR debug_base,
+ CORE_ADDR lm)
{
struct so_list *tail;
CORE_ADDR prev_lm;
@@ -1727,8 +1771,15 @@ solist_update_incremental (struct svr4_info *info, CORE_ADDR lm)
for (tail = info->solib_list; tail->next != NULL; tail = tail->next)
/* Nothing. */;
- lm_info_svr4 *li = (lm_info_svr4 *) tail->lm_info;
- prev_lm = li->lm_addr;
+ /* Don't check shared libraries in other namespaces when updating
+ shared libraries in a new namespace. */
+ if (debug_base == info->debug_base)
+ {
+ lm_info_svr4 *li = (lm_info_svr4 *) tail->lm_info;
+ prev_lm = li->lm_addr;
+ }
+ else
+ prev_lm = 0;
/* Read the new objects. */
if (info->using_xfer)
@@ -1869,13 +1920,6 @@ svr4_handle_solib_event (void)
return;
}
- /* GDB does not currently support libraries loaded via dlmopen
- into namespaces other than the initial one. We must ignore
- any namespace other than the initial namespace here until
- support for this is added to GDB. */
- if (debug_base != info->debug_base)
- action = DO_NOTHING;
-
if (action == UPDATE_OR_RELOAD)
{
try
@@ -1901,7 +1945,7 @@ svr4_handle_solib_event (void)
if (action == UPDATE_OR_RELOAD)
{
- if (!solist_update_incremental (info, lm))
+ if (!solist_update_incremental (info, debug_base, lm))
action = FULL_RELOAD;
}
@@ -2136,7 +2180,7 @@ enable_break (struct svr4_info *info, int from_tty)
solib_add (NULL, from_tty, auto_solib_add);
sym_addr = 0;
- if (info->debug_base && solib_svr4_r_map (info) != 0)
+ if (info->debug_base && solib_svr4_r_map (info->debug_base) != 0)
sym_addr = solib_svr4_r_brk (info);
if (sym_addr != 0)
@@ -3087,6 +3131,7 @@ svr4_ilp32_fetch_link_map_offsets (void)
lmo.r_map_offset = 4;
lmo.r_brk_offset = 8;
lmo.r_ldsomap_offset = 20;
+ lmo.r_next_offset = -1;
/* Everything we need is in the first 20 bytes. */
lmo.link_map_size = 20;
@@ -3118,6 +3163,7 @@ svr4_lp64_fetch_link_map_offsets (void)
lmo.r_map_offset = 8;
lmo.r_brk_offset = 16;
lmo.r_ldsomap_offset = 40;
+ lmo.r_next_offset = -1;
/* Everything we need is in the first 40 bytes. */
lmo.link_map_size = 40;
diff --git a/gdb/solib-svr4.h b/gdb/solib-svr4.h
index 8d94d9cb26e..64854e2edd9 100644
--- a/gdb/solib-svr4.h
+++ b/gdb/solib-svr4.h
@@ -66,6 +66,9 @@ struct link_map_offsets
/* Offset of r_debug.r_ldsomap. */
int r_ldsomap_offset;
+ /* Offset of r_debug_extended.r_next. */
+ int r_next_offset;
+
/* Size of struct link_map (or equivalent), or at least enough of it
to be able to obtain the fields below. */
int link_map_size;
diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc
index d27a2169029..5c3503ba69f 100644
--- a/gdbserver/linux-low.cc
+++ b/gdbserver/linux-low.cc
@@ -6733,6 +6733,9 @@ struct link_map_offsets
/* Offset and size of r_debug.r_map. */
int r_map_offset;
+ /* Offset of r_debug_extended.r_next. */
+ int r_next_offset;
+
/* Offset to l_addr field in struct link_map. */
int l_addr_offset;
@@ -6749,117 +6752,59 @@ struct link_map_offsets
int l_prev_offset;
};
-/* Construct qXfer:libraries-svr4:read reply. */
+static const struct link_map_offsets lmo_32bit_offsets =
+ {
+ 0, /* r_version offset. */
+ 4, /* r_debug.r_map offset. */
+ 20, /* r_debug_extended.r_next. */
+ 0, /* l_addr offset in link_map. */
+ 4, /* l_name offset in link_map. */
+ 8, /* l_ld offset in link_map. */
+ 12, /* l_next offset in link_map. */
+ 16 /* l_prev offset in link_map. */
+ };
-int
-linux_process_target::qxfer_libraries_svr4 (const char *annex,
- unsigned char *readbuf,
- unsigned const char *writebuf,
- CORE_ADDR offset, int len)
-{
- struct process_info_private *const priv = current_process ()->priv;
- char filename[PATH_MAX];
- int pid, is_elf64;
+static const struct link_map_offsets lmo_64bit_offsets =
+ {
+ 0, /* r_version offset. */
+ 8, /* r_debug.r_map offset. */
+ 40, /* r_debug_extended.r_next. */
+ 0, /* l_addr offset in link_map. */
+ 8, /* l_name offset in link_map. */
+ 16, /* l_ld offset in link_map. */
+ 24, /* l_next offset in link_map. */
+ 32 /* l_prev offset in link_map. */
+ };
- static const struct link_map_offsets lmo_32bit_offsets =
- {
- 0, /* r_version offset. */
- 4, /* r_debug.r_map offset. */
- 0, /* l_addr offset in link_map. */
- 4, /* l_name offset in link_map. */
- 8, /* l_ld offset in link_map. */
- 12, /* l_next offset in link_map. */
- 16 /* l_prev offset in link_map. */
- };
+/* Get the loaded shared libraries from one namespace. */
- static const struct link_map_offsets lmo_64bit_offsets =
- {
- 0, /* r_version offset. */
- 8, /* r_debug.r_map offset. */
- 0, /* l_addr offset in link_map. */
- 8, /* l_name offset in link_map. */
- 16, /* l_ld offset in link_map. */
- 24, /* l_next offset in link_map. */
- 32 /* l_prev offset in link_map. */
- };
- const struct link_map_offsets *lmo;
- unsigned int machine;
- int ptr_size;
+static void
+read_link_map (std::string &document, CORE_ADDR r_debug, int ptr_size,
+ const struct link_map_offsets *lmo, bool ignore_first,
+ int &header_done)
+{
CORE_ADDR lm_addr = 0, lm_prev = 0;
CORE_ADDR l_name, l_addr, l_ld, l_next, l_prev;
- int header_done = 0;
-
- if (writebuf != NULL)
- return -2;
- if (readbuf == NULL)
- return -1;
-
- pid = lwpid_of (current_thread);
- xsnprintf (filename, sizeof filename, "/proc/%d/exe", pid);
- is_elf64 = elf_64_file_p (filename, &machine);
- lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets;
- ptr_size = is_elf64 ? 8 : 4;
-
- while (annex[0] != '\0')
- {
- const char *sep;
- CORE_ADDR *addrp;
- int name_len;
-
- sep = strchr (annex, '=');
- if (sep == NULL)
- break;
-
- name_len = sep - annex;
- if (name_len == 5 && startswith (annex, "start"))
- addrp = &lm_addr;
- else if (name_len == 4 && startswith (annex, "prev"))
- addrp = &lm_prev;
- else
- {
- annex = strchr (sep, ';');
- if (annex == NULL)
- break;
- annex++;
- continue;
- }
-
- annex = decode_address_to_semicolon (addrp, sep + 1);
- }
if (lm_addr == 0)
{
int r_version = 0;
- if (priv->r_debug == 0)
- priv->r_debug = get_r_debug (pid, is_elf64);
-
- /* We failed to find DT_DEBUG. Such situation will not change
- for this inferior - do not retry it. Report it to GDB as
- E01, see for the reasons at the GDB solib-svr4.c side. */
- if (priv->r_debug == (CORE_ADDR) -1)
- return -1;
-
- if (priv->r_debug != 0)
+ if (linux_read_memory (r_debug + lmo->r_version_offset,
+ (unsigned char *) &r_version,
+ sizeof (r_version)) != 0
+ || r_version < 1)
{
- if (linux_read_memory (priv->r_debug + lmo->r_version_offset,
- (unsigned char *) &r_version,
- sizeof (r_version)) != 0
- || r_version < 1)
- {
- warning ("unexpected r_debug version %d", r_version);
- }
- else if (read_one_ptr (priv->r_debug + lmo->r_map_offset,
- &lm_addr, ptr_size) != 0)
- {
- warning ("unable to read r_map from 0x%lx",
- (long) priv->r_debug + lmo->r_map_offset);
- }
+ warning ("unexpected r_debug version %d", r_version);
+ }
+ else if (read_one_ptr (r_debug + lmo->r_map_offset,
+ &lm_addr, ptr_size) != 0)
+ {
+ warning ("unable to read r_map from 0x%lx",
+ (long) r_debug + lmo->r_map_offset);
}
}
- std::string document = "<library-list-svr4 version=\"1.0\"";
-
while (lm_addr
&& read_one_ptr (lm_addr + lmo->l_name_offset,
&l_name, ptr_size) == 0
@@ -6887,7 +6832,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
(see solib-svr4.c parameter ignore_first). But in such case the main
executable does not have PT_DYNAMIC present and this function already
exited above due to failed get_r_debug. */
- if (lm_prev == 0)
+ if (ignore_first && lm_prev == 0)
string_appendf (document, " main-lm=\"0x%lx\"", (unsigned long) lm_addr);
else
{
@@ -6917,6 +6862,119 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex,
lm_prev = lm_addr;
lm_addr = l_next;
}
+}
+
+/* Find the next namespace from the r_next field. */
+
+static CORE_ADDR
+get_r_next (CORE_ADDR r_debug, int ptr_size,
+ const struct link_map_offsets *lmo)
+{
+ int r_version = 0;
+ CORE_ADDR lm_addr = 0;
+ if (linux_read_memory (r_debug + lmo->r_version_offset,
+ (unsigned char *) &r_version,
+ sizeof (r_version)) == 0
+ && r_version >= 2)
+ {
+ if (read_one_ptr (r_debug + lmo->r_next_offset,
+ &lm_addr, ptr_size) != 0)
+ warning ("unable to read r_next from 0x%lx",
+ (long) r_debug + lmo->r_next_offset);
+ }
+ return lm_addr;
+}
+
+/* Construct qXfer:libraries-svr4:read reply. */
+
+int
+linux_process_target::qxfer_libraries_svr4 (const char *annex,
+ unsigned char *readbuf,
+ unsigned const char *writebuf,
+ CORE_ADDR offset, int len)
+{
+ struct process_info_private *const priv = current_process ()->priv;
+ char filename[PATH_MAX];
+ int pid, is_elf64;
+ unsigned int machine;
+ CORE_ADDR lm_addr = 0, lm_prev = 0;
+ int header_done = 0;
+
+ if (writebuf != NULL)
+ return -2;
+ if (readbuf == NULL)
+ return -1;
+
+ pid = lwpid_of (current_thread);
+ xsnprintf (filename, sizeof filename, "/proc/%d/exe", pid);
+ is_elf64 = elf_64_file_p (filename, &machine);
+ const struct link_map_offsets *lmo;
+ int ptr_size;
+ if (is_elf64)
+ {
+ lmo = &lmo_64bit_offsets;
+ ptr_size = 8;
+ }
+ else
+ {
+ lmo = &lmo_32bit_offsets;
+ ptr_size = 4;
+ }
+ CORE_ADDR r_debug = priv->r_debug;
+ if (r_debug == 0)
+ r_debug = get_r_debug (pid, is_elf64);
+
+ /* We failed to find DT_DEBUG. Such situation will not change
+ for this inferior - do not retry it. Report it to GDB as
+ E01, see for the reasons at the GDB solib-svr4.c side. */
+ if (r_debug == (CORE_ADDR) -1)
+ return -1;
+
+ while (annex[0] != '\0')
+ {
+ const char *sep;
+ CORE_ADDR *addrp;
+ int name_len;
+
+ sep = strchr (annex, '=');
+ if (sep == NULL)
+ break;
+
+ name_len = sep - annex;
+ if (name_len == 5 && startswith (annex, "start"))
+ addrp = &lm_addr;
+ else if (name_len == 4 && startswith (annex, "prev"))
+ addrp = &lm_prev;
+ else
+ {
+ annex = strchr (sep, ';');
+ if (annex == NULL)
+ break;
+ annex++;
+ continue;
+ }
+
+ annex = decode_address_to_semicolon (addrp, sep + 1);
+ }
+
+ std::string document = "<library-list-svr4 version=\"1.0\"";
+
+ if (r_debug != 0)
+ {
+ /* Ignore the first entry in the default namespace. */
+ read_link_map (document, r_debug, ptr_size, lmo, true,
+ header_done);
+ /* Get the next namespace from the r_next field. */
+ CORE_ADDR lm_next = get_r_next (r_debug, ptr_size, lmo);
+ while (lm_next)
+ {
+ /* Keep the first entry in the non-default namespace. */
+ read_link_map (document, lm_next, ptr_size, lmo, false,
+ header_done);
+ /* Go to the next namespace. */
+ lm_next = get_r_next (lm_next, ptr_size, lmo);
+ }
+ }
if (!header_done)
{
--
2.31.1
next reply other threads:[~2021-10-02 0:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-02 0:11 H.J. Lu [this message]
2021-10-02 20:43 ` [PATCH v3] " H.J. Lu
2022-02-10 23:08 ` Kevin Buettner
2022-02-16 0:43 ` H.J. Lu
2022-02-16 11:10 ` Metzger, Markus T
2022-02-21 6:53 ` Metzger, Markus T
2022-02-25 16:53 ` Metzger, Markus T
2022-02-25 20:25 ` Kevin Buettner
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