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From: Markus Metzger <mmetzger@sourceware.org> To: gdb-cvs@sourceware.org Subject: [binutils-gdb] gdb, gdbserver: extend RSP to support namespaces Date: Tue, 18 Oct 2022 13:25:03 +0000 (GMT) [thread overview] Message-ID: <20221018132503.18A9038582A6@sourceware.org> (raw) https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=2733d9d5d62c62023dc2d7a93fa5afa22f386ffd commit 2733d9d5d62c62023dc2d7a93fa5afa22f386ffd Author: Markus Metzger <markus.t.metzger@intel.com> Date: Tue Mar 15 18:08:06 2022 +0100 gdb, gdbserver: extend RSP to support namespaces Introduce a new qXfer:libraries-svr4:read annex key/value pair lmid=<namespace identifier> to be used together with start and prev to provide the namespace of start and prev to gdbserver. Unknown key/value pairs are ignored by gdbserver so no new supports check is needed. Introduce a new library-list-svr4 library attribute lmid to provide the namespace of a library entry to GDB. This implementation uses the address of a namespace's r_debug object as namespace identifier. This should have incremented the minor version but since unknown XML attributes are ignored, anyway, and since changing the version results in a warning from GDB, the version is left at 1.0. Diff: --- gdb/doc/gdb.texinfo | 16 ++++++++++++++-- gdb/features/library-list-svr4.dtd | 4 ++++ gdb/solib-svr4.c | 38 +++++++++++++++++++++++++++++++++++--- gdbserver/linux-low.cc | 26 +++++++++++++++++--------- 4 files changed, 70 insertions(+), 14 deletions(-) diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index 3de511a4844..ea66f4ee42d 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -43706,6 +43706,12 @@ specified by the @samp{start} argument. If unset or zero then the remote stub will expect that no @samp{struct link_map} exists prior to the starting point. +@item lmid=@var{lmid} +A hexadecimal number specifying a namespace identifier. This is +currently only used together with @samp{start} to provide the +namespace identifier back to @value{GDBN} in the response. +@value{GDBN} will only provide values that were previously reported to +it. If unset, the response will include @samp{lmid="0x0"}. @end table Arguments that are not understood by the remote stub will be silently @@ -46244,6 +46250,11 @@ memory address. It is a displacement of absolute memory address against address the file was prelinked to during the library load. @item @code{l_ld}, which is memory address of the @code{PT_DYNAMIC} segment +@item +@code{lmid}, which is an identifier for a linker namespace, such as +the memory address of the @code{r_debug} object that contains this +namespace's load map or the namespace identifier returned by +@code{dlinfo (3)}. @end itemize Additionally the single @code{main-lm} attribute specifies address of @@ -46259,9 +46270,9 @@ looks like this: @smallexample <library-list-svr4 version="1.0" main-lm="0xe4f8f8"> <library name="/lib/ld-linux.so.2" lm="0xe4f51c" l_addr="0xe2d000" - l_ld="0xe4eefc"/> + l_ld="0xe4eefc" lmid="0xfffe0"/> <library name="/lib/libc.so.6" lm="0xe4fbe8" l_addr="0x154000" - l_ld="0x152350"/> + l_ld="0x152350" lmid="0xfffe0"/> </library-list-svr> @end smallexample @@ -46277,6 +46288,7 @@ The format of an SVR4 library list is described by this DTD: <!ATTLIST library lm CDATA #REQUIRED> <!ATTLIST library l_addr CDATA #REQUIRED> <!ATTLIST library l_ld CDATA #REQUIRED> +<!ATTLIST library lmid CDATA #IMPLIED> @end smallexample @node Memory Map Format diff --git a/gdb/features/library-list-svr4.dtd b/gdb/features/library-list-svr4.dtd index 7d62354c34c..e869ff1349e 100644 --- a/gdb/features/library-list-svr4.dtd +++ b/gdb/features/library-list-svr4.dtd @@ -14,3 +14,7 @@ <!ATTLIST library lm CDATA #REQUIRED> <!ATTLIST library l_addr CDATA #REQUIRED> <!ATTLIST library l_ld CDATA #REQUIRED> +<!-- added lmid attribute to what should have become version 1.1 but + since this generates a warning in GDB and since unknown attributes + are ignored, anyway, leaving the version at 1.0. --> +<!ATTLIST library lmid CDATA #IMPLIED> diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c index a80e7e30561..295e9b8b69d 100644 --- a/gdb/solib-svr4.c +++ b/gdb/solib-svr4.c @@ -1067,8 +1067,37 @@ library_list_start_library (struct gdb_xml_parser *parser, new_elem->so_name[sizeof (new_elem->so_name) - 1] = 0; strcpy (new_elem->so_original_name, new_elem->so_name); - *list->tailp = new_elem; - list->tailp = &new_elem->next; + /* Older versions did not supply lmid. Put the element into the flat + list of the special namespace zero in that case. */ + gdb_xml_value *at_lmid = xml_find_attribute (attributes, "lmid"); + if (at_lmid == nullptr) + { + *list->tailp = new_elem; + list->tailp = &new_elem->next; + } + else + { + ULONGEST lmid = *(ULONGEST *) at_lmid->value.get (); + + /* Ensure that the element is actually initialized. */ + if (list->solib_lists.find (lmid) == list->solib_lists.end ()) + list->solib_lists[lmid] = nullptr; + + so_list **psolist = &list->solib_lists[lmid]; + so_list **pnext = psolist; + + /* Walk to the end of the list if we have one. */ + so_list *solist = *psolist; + if (solist != nullptr) + { + for (; solist->next != nullptr; solist = solist->next) + /* Nothing. */; + + pnext = &solist->next; + } + + *pnext = new_elem; + } } /* Handle the start of a <library-list-svr4> element. */ @@ -1108,6 +1137,7 @@ static const struct gdb_xml_attribute svr4_library_attributes[] = { "lm", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, { "l_addr", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, { "l_ld", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, + { "lmid", GDB_XML_AF_NONE, gdb_xml_parse_attr_ulongest, NULL }, { NULL, GDB_XML_AF_NONE, NULL, NULL } }; @@ -1869,7 +1899,9 @@ solist_update_incremental (svr4_info *info, CORE_ADDR debug_base, struct svr4_library_list library_list; char annex[64]; - xsnprintf (annex, sizeof (annex), "start=%s;prev=%s", + /* Unknown key=value pairs are ignored by the gdbstub. */ + xsnprintf (annex, sizeof (annex), "lmid=%s;start=%s;prev=%s", + phex_nz (debug_base, sizeof (debug_base)), phex_nz (lm, sizeof (lm)), phex_nz (prev_lm, sizeof (prev_lm))); if (!svr4_current_sos_via_xfer_libraries (&library_list, annex)) diff --git a/gdbserver/linux-low.cc b/gdbserver/linux-low.cc index e83ccceed83..4754366d443 100644 --- a/gdbserver/linux-low.cc +++ b/gdbserver/linux-low.cc @@ -6489,8 +6489,8 @@ static const link_map_offsets lmo_64bit_offsets = /* Get the loaded shared libraries from one namespace. */ static void -read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev, - int ptr_size, const link_map_offsets *lmo) +read_link_map (std::string &document, CORE_ADDR lmid, CORE_ADDR lm_addr, + CORE_ADDR lm_prev, int ptr_size, const link_map_offsets *lmo) { CORE_ADDR l_name, l_addr, l_ld, l_next, l_prev; @@ -6525,9 +6525,9 @@ read_link_map (std::string &document, CORE_ADDR lm_addr, CORE_ADDR lm_prev, string_appendf (document, "<library name=\""); xml_escape_text_append (&document, (char *) libname); string_appendf (document, "\" lm=\"0x%s\" l_addr=\"0x%s\" " - "l_ld=\"0x%s\"/>", + "l_ld=\"0x%s\" lmid=\"0x%s\"/>", paddress (lm_addr), paddress (l_addr), - paddress (l_ld)); + paddress (l_ld), paddress (lmid)); } lm_prev = lm_addr; @@ -6547,7 +6547,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex, char filename[PATH_MAX]; int pid, is_elf64; unsigned int machine; - CORE_ADDR lm_addr = 0, lm_prev = 0; + CORE_ADDR lmid = 0, lm_addr = 0, lm_prev = 0; if (writebuf != NULL) return -2; @@ -6581,7 +6581,9 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex, break; name_len = sep - annex; - if (name_len == 5 && startswith (annex, "start")) + if (name_len == 4 && startswith (annex, "lmid")) + addrp = &lmid; + else if (name_len == 5 && startswith (annex, "start")) addrp = &lm_addr; else if (name_len == 4 && startswith (annex, "prev")) addrp = &lm_prev; @@ -6600,19 +6602,25 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex, std::string document = "<library-list-svr4 version=\"1.0\""; /* When the starting LM_ADDR is passed in the annex, only traverse that - namespace. + namespace, which is assumed to be identified by LMID. Otherwise, start with R_DEBUG and traverse all namespaces we find. */ if (lm_addr != 0) { document += ">"; - read_link_map (document, lm_addr, lm_prev, ptr_size, lmo); + read_link_map (document, lmid, lm_addr, lm_prev, ptr_size, lmo); } else { if (lm_prev != 0) warning ("ignoring prev=0x%s without start", paddress (lm_prev)); + /* We could interpret LMID as 'provide only the libraries for this + namespace' but GDB is currently only providing lmid, start, and + prev, or nothing. */ + if (lmid != 0) + warning ("ignoring lmid=0x%s without start", paddress (lmid)); + CORE_ADDR r_debug = priv->r_debug; if (r_debug == 0) r_debug = priv->r_debug = get_r_debug (pid, is_elf64); @@ -6678,7 +6686,7 @@ linux_process_target::qxfer_libraries_svr4 (const char *annex, } } - read_link_map (document, lm_addr, lm_prev, ptr_size, lmo); + read_link_map (document, r_debug, lm_addr, lm_prev, ptr_size, lmo); if (r_version < 2) break;
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