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Re: [patch 6/6] gdbserver build-id attribute generator
- From: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- To: Aleksandar Ristovski <aristovski at qnx dot com>
- Cc: "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Sun, 31 Mar 2013 19:43:22 +0200
- Subject: Re: [patch 6/6] gdbserver build-id attribute generator
- References: <51278984 dot 3070208 at qnx dot com> <20130310210843 dot GG21130 at host2 dot jankratochvil dot net> <514C56D4 dot 1060906 at qnx dot com> <20130326204157 dot GC12291 at host2 dot jankratochvil dot net> <51530465 dot 30503 at qnx dot com> <20130327145028 dot GA17905 at host2 dot jankratochvil dot net> <515353CF dot 40601 at qnx dot com> <5154ADD2 dot 9040206 at qnx dot com>
On Thu, 28 Mar 2013 21:53:38 +0100, Aleksandar Ristovski wrote:
> Fixed patch. I haven't addressed any of your concerns except fixed
> what was broken. There are two things changed:
>
> 1) get_dynamic, you will see I left it unfinished when switched to
> generic "find_phdr" to address phdr traversal duplication code.
I wrote at "find_phdr_p":
But I do not understand why this function exists
which probably corresponds to this your comment.
> 2) lrfind_mapping_entry can not check for vaddr + offset as offset
> is file offset, and for some shared objects this will not match even
> though the vaddr of the entry with zero offset is valid.
Oops, you are right:
7ffff7ddc000-7ffff7dfd000 r-xp 00000000 fd:01 51415762 /usr/lib64/ld-2.17.so
7ffff7ffc000-7ffff7ffe000 rw-p 00020000 fd:01 51415762 /usr/lib64/ld-2.17.so
(gdb) p/x 0x7ffff7ffc000-0x7ffff7ddc000
$1 = 0x220000
It is mapped by additional displacement of 2MB. Adjustment is suggested below.
BTW for gdbserver compatibility I have posted:
[patch 1/2+7.6] /proc/PID/smaps: filename fix
http://sourceware.org/ml/gdb-patches/2013-03/msg01120.html
[patch 2/2+7.6] /proc/PID/smaps: Linux kernel 3.8.3 compat.
http://sourceware.org/ml/gdb-patches/2013-03/msg01119.html
but you probably did not face this compat. problem.
> Stepping through code now shows some of the things you couldn't see,
> like e.g. why is there so->build_id, and where is it being set (you
> couldn't see it being set before as qXfer_library was broken).
>
>
> ---
> Aleksandar
>
>
>
> On 13-03-27 04:17 PM, Aleksandar Ristovski wrote:
> >Addressed Jan's comments.
> >
> >
> >
> >On 13-03-27 10:50 AM, Jan Kratochvil wrote:
> >>On Wed, 27 Mar 2013 15:38:29 +0100, Aleksandar Ristovski wrote:
> >>>On 13-03-26 04:41 PM, Jan Kratochvil wrote:
> >>>>>>+ if (build_id_list_p)
> >>>>>>+ qsort (VEC_address (build_id_list_s, data.list),
> >>>>>>+ VEC_length (build_id_list_s, data.list),
> >>>>>>+ sizeof (build_id_list_s), compare_build_id_list);
> >>>>It is always already sorted by Linux kernel, rather a for cycle to
> >>>>verify it
> >>>>really is sorted.
> >>>
> >>>Can we guarantee this is always the case?
> >>
> >>Yes.
> >>
> >>The problem is that if it is unsorted there is a bug somewhere and
> >>that qsort
> >>will hide that bug.
> >
> >
> >Qsort removed. I didn't put any traversal; we are making assumption that
> >the list will be sorted. The checks in the other bits make sure that we
> >either find the right mapping or none at all, so worst case scenario is
> >we don't get build-id communicated to gdb.
> >
> >
> >
> >Thanks,
> >
> >Aleksandar
> >
>
> >From 80cd24335bcff6625b5c69c1b2f2d43142db08d1 Mon Sep 17 00:00:00 2001
> From: Aleksandar Ristovski <ARistovski@qnx.com>
> Date: Wed, 27 Mar 2013 11:56:57 -0400
> Subject: [PATCH 6/8] gdbserver build-id attribute generator
>
> * doc/gdb.texinfo (Library List Format for SVR4 Targets): Add
> 'build-id' in description, example, new attribute in dtd.
> * features/library-list-svr4.dtd (library-list-svr4): New
> 'build-id' attribute.
> * linux-low.c (linux-maps.h, search.h): Include.
> (find_phdr_p_ftype, find_phdr, find_phdr_p): New.
> (get_dynamic): Use find_pdhr to traverse program headers.
> (struct mapping_entry): New structure.
> (mapping_entry_s): New typedef, new vector type def.
> (free_mapping_entry, compare_mapping_entry,
> compare_mapping_entry_range, compare_mapping_entry_inode): New.
> (struct find_memory_region_callback_data): New.
> (find_memory_region_callback): New fwd. declaration.
> (read_build_id, find_memory_region_callback, get_hex_build_id): New.
> (linux_qxfer_libraries_svr4): Add optional build-id attribute
> to reply XML document.
> ---
> gdb/doc/gdb.texinfo | 17 +-
> gdb/features/library-list-svr4.dtd | 13 +-
> gdb/gdbserver/linux-low.c | 388 +++++++++++++++++++++++++++++++++---
> 3 files changed, 381 insertions(+), 37 deletions(-)
>
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 38ce259..7c17209 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -40323,6 +40323,8 @@ 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{build-id}, hex encoded @code{NT_GNU_BUID_ID} note, if it exists.
Typo: NT_GNU_BUILD_ID
> @end itemize
>
> Additionally the single @code{main-lm} attribute specifies address of
> @@ -40340,7 +40342,7 @@ looks like this:
> <library name="/lib/ld-linux.so.2" lm="0xe4f51c" l_addr="0xe2d000"
> l_ld="0xe4eefc"/>
> <library name="/lib/libc.so.6" lm="0xe4fbe8" l_addr="0x154000"
> - l_ld="0x152350"/>
> + l_ld="0x152350" build-id="9afccf7cc41e6293476223fe72480854"/>
> </library-list-svr>
> @end smallexample
>
> @@ -40349,13 +40351,14 @@ The format of an SVR4 library list is described by this DTD:
> @smallexample
> <!-- library-list-svr4: Root element with versioning -->
> <!ELEMENT library-list-svr4 (library)*>
> -<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
> -<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
> +<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
> +<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
> <!ELEMENT library EMPTY>
> -<!ATTLIST library name CDATA #REQUIRED>
> -<!ATTLIST library lm CDATA #REQUIRED>
> -<!ATTLIST library l_addr CDATA #REQUIRED>
> -<!ATTLIST library l_ld CDATA #REQUIRED>
> +<!ATTLIST library name CDATA #REQUIRED>
> +<!ATTLIST library lm CDATA #REQUIRED>
> +<!ATTLIST library l_addr CDATA #REQUIRED>
> +<!ATTLIST library l_ld CDATA #REQUIRED>
> +<!ATTLIST library build-id 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 cae7fd8..fdd6ec0 100644
> --- a/gdb/features/library-list-svr4.dtd
> +++ b/gdb/features/library-list-svr4.dtd
> @@ -6,11 +6,12 @@
>
> <!-- library-list-svr4: Root element with versioning -->
> <!ELEMENT library-list-svr4 (library)*>
> -<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
> -<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
> +<!ATTLIST library-list-svr4 version CDATA #FIXED "1.0">
> +<!ATTLIST library-list-svr4 main-lm CDATA #IMPLIED>
>
> <!ELEMENT library EMPTY>
> -<!ATTLIST library name CDATA #REQUIRED>
> -<!ATTLIST library lm CDATA #REQUIRED>
> -<!ATTLIST library l_addr CDATA #REQUIRED>
> -<!ATTLIST library l_ld CDATA #REQUIRED>
> +<!ATTLIST library name CDATA #REQUIRED>
> +<!ATTLIST library lm CDATA #REQUIRED>
> +<!ATTLIST library l_addr CDATA #REQUIRED>
> +<!ATTLIST library l_ld CDATA #REQUIRED>
> +<!ATTLIST library build-id CDATA #IMPLIED>
> diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
> index 72c51e0..aa248e9 100644
> --- a/gdb/gdbserver/linux-low.c
> +++ b/gdb/gdbserver/linux-low.c
> @@ -20,6 +20,7 @@
> #include "linux-low.h"
> #include "linux-osdata.h"
> #include "agent.h"
> +#include "linux-maps.h"
>
> #include "gdb_wait.h"
> #include <stdio.h>
> @@ -43,6 +44,7 @@
> #include "gdb_stat.h"
> #include <sys/vfs.h>
> #include <sys/uio.h>
> +#include <search.h>
> #ifndef ELFMAG0
> /* Don't include <linux/elf.h> here. If it got included by gdb_proc_service.h
> then ELFMAG0 will have been defined. If it didn't get included by
> @@ -5432,15 +5434,81 @@ get_phdr_phnum_from_proc_auxv (const int pid, const int is_elf64,
> return 0;
> }
>
> +
Extra empty line, there should be only one empty line.
> +/* Predicate function type returns 1 if the given phdr is what is
> + being looked for. Returns 0 otherwise. */
> +
> +typedef int (*find_phdr_p_ftype)(const void *phdr, int is_elf64,
> + const void *data);
GNU Coding Standards formatting:
typedef int (*find_phdr_p_ftype) (const void *phdr, int is_elf64,
GDB uses *_ftype types without that * pointer,
use then find_phdr_p_ftype *find_phdr_p.
> +
> +/* Linearly traverse pheaders given in PHDR until supplied
program headers given between PHDR_BEGIN and PHDR_END
> + predicate function returns 1. If supplied predicate function
> + did return 1, stop traversal and return that PHDR. */
that program header.
> +
> +static const void *
> +find_phdr (int is_elf64, const void *const phdr_begin,
> + const void *const phdr_end, find_phdr_p_ftype find_phdr_p,
Use find_phdr_p_ftype *find_phdr_p.
> + const void *const data)
> +{
> +#define SIZEOFHDR(hdr) (is_elf64? sizeof((hdr)._64) : sizeof((hdr)._32))
GNU Coding Standards formatting:
#define SIZEOFHDR(hdr) (is_elf64 ? sizeof ((hdr)._64) : sizeof ((hdr)._32))
But in fact I do not see why you define a macro which is used only once.
> +#define PHDR_NEXT(hdrp) ((void *) ((char *)(hdrp) + SIZEOFHDR(*hdrp)))
GNU Coding Standards formatting and also parentheses around each macro
parameter:
#define PHDR_NEXT(hdrp) ((void *) ((char *) (hdrp) + SIZEOFHDR (*hdrp)))
But as GDB codebase allows void * arithmetics it can be simplified to (also
putting there const otherwise it deconstifies the passed in pointer):
#define PHDR_NEXT(hdrp) (((const void *) (hdrp) + SIZEOFHDR (*hdrp)))
> +
> + union ElfXX_Phdr
> + {
> + Elf32_Phdr _32;
> + Elf64_Phdr _64;
> + } const *phdr = phdr_begin;
> +
> + if (phdr == NULL)
> + return NULL;
> +
> + while (PHDR_NEXT (phdr) <= phdr_end)
> + {
> + if (find_phdr_p (phdr, is_elf64, data) == 1)
> + return phdr;
> + phdr = PHDR_NEXT (phdr);
> + }
> +
> + return NULL;
> +#undef PHDR_NEXT
> +#undef SIZEOFHDR
> +}
> +
Missing function comment.
> +
> +static int
> +find_phdr_p (const void *const phdr, const int is_elf64,
> + const void *const data)
But I do not understand why this function exists - it could be integrated in
find_phdr as very every caller of find_phdr passse as find_phdr_p parameter
this find_phdr_p implementation.
> +{
> + const ULONGEST *const type = data;
> +
> + if (is_elf64)
> + {
> + const Elf64_Phdr *const p = phdr;
> +
> + if (p->p_type == *type)
> + return 1;
> + }
> + else
> + {
> + const Elf32_Phdr *const p = phdr;
> +
> + if (p->p_type == *type)
> + return 1;
> + }
> + return 0;
> +}
> +
> /* Return &_DYNAMIC (via PT_DYNAMIC) in the inferior, or 0 if not present. */
>
> static CORE_ADDR
> get_dynamic (const int pid, const int is_elf64)
> {
> CORE_ADDR phdr_memaddr, relocation;
> - int num_phdr, i;
> + int num_phdr;
> unsigned char *phdr_buf;
> const int phdr_size = is_elf64 ? sizeof (Elf64_Phdr) : sizeof (Elf32_Phdr);
> + const void *phdr;
> + ULONGEST p_type;
>
> if (get_phdr_phnum_from_proc_auxv (pid, is_elf64, &phdr_memaddr, &num_phdr))
> return 0;
> @@ -5454,21 +5522,24 @@ get_dynamic (const int pid, const int is_elf64)
> /* Compute relocation: it is expected to be 0 for "regular" executables,
> non-zero for PIE ones. */
> relocation = -1;
> - for (i = 0; relocation == -1 && i < num_phdr; i++)
> - if (is_elf64)
> - {
> - Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size);
> + p_type = PT_PHDR;
> + phdr = find_phdr (is_elf64, phdr_buf, phdr_buf + num_phdr * phdr_size,
> + find_phdr_p, &p_type);
> + if (phdr != NULL)
> + {
> + if (is_elf64)
> + {
> + const Elf64_Phdr *const p = phdr;
>
> - if (p->p_type == PT_PHDR)
> relocation = phdr_memaddr - p->p_vaddr;
> - }
> - else
> - {
> - Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size);
> + }
> + else
> + {
> + const Elf32_Phdr *const p = phdr;
>
> - if (p->p_type == PT_PHDR)
> relocation = phdr_memaddr - p->p_vaddr;
> - }
> + }
> + }
>
> if (relocation == -1)
> {
> @@ -5485,21 +5556,23 @@ get_dynamic (const int pid, const int is_elf64)
> return 0;
> }
>
> - for (i = 0; i < num_phdr; i++)
> + p_type = PT_DYNAMIC;
> + phdr = find_phdr (is_elf64, phdr_buf, phdr_buf + num_phdr * phdr_size,
> + find_phdr_p, &p_type);
> +
> + if (phdr != NULL)
> {
> if (is_elf64)
> {
> - Elf64_Phdr *const p = (Elf64_Phdr *) (phdr_buf + i * phdr_size);
> + const Elf64_Phdr *const p = phdr;
>
> - if (p->p_type == PT_DYNAMIC)
> - return p->p_vaddr + relocation;
> + return p->p_vaddr + relocation;
> }
> else
> {
> - Elf32_Phdr *const p = (Elf32_Phdr *) (phdr_buf + i * phdr_size);
> + const Elf32_Phdr *const p = phdr;
>
> - if (p->p_type == PT_DYNAMIC)
> - return p->p_vaddr + relocation;
> + return p->p_vaddr + relocation;
> }
> }
>
> @@ -5641,6 +5714,255 @@ struct link_map_offsets
> int l_prev_offset;
> };
>
> +
> +/* Structure for holding a mapping. Only mapping
> + containing l_ld can have hex_build_id set.
> +
> + Fields are populated from linux_find_memory_region parameters. */
> +
> +struct mapping_entry
> +{
Here should be the line:
/* Fields are populated from linux_find_memory_region parameters. */
> + ULONGEST vaddr;
> + ULONGEST size;
> + ULONGEST offset;
> + ULONGEST inode;
> +
> + /* Hex encoded string allocated using xmalloc, and
> + needs to be freed. It can be NULL. */
> +
> + char *hex_build_id;
> +};
> +
> +typedef struct mapping_entry mapping_entry_s;
> +
> +DEF_VEC_O(mapping_entry_s);
> +
> +static void
> +free_mapping_entry (VEC (mapping_entry_s) *lst)
> +{
> + int ix;
> + mapping_entry_s *p;
> +
> + for (ix = 0; VEC_iterate (mapping_entry_s, lst, ix, p); ++ix)
> + xfree (p->hex_build_id);
> +
> + VEC_free (mapping_entry_s, lst);
> +}
> +
> +/* Used for finding a mapping containing the given
> + l_ld passed in K. */
> +
> +static int
> +compare_mapping_entry_range (const void *const k, const void *const b)
> +{
> + const ULONGEST key = *(CORE_ADDR*) k;
> + const mapping_entry_s *const p = b;
> +
> + if (key < p->vaddr)
> + return -1;
> +
> + if (key < p->vaddr + p->size)
> + return 0;
> +
> + return 1;
> +}
> +
> +struct find_memory_region_callback_data
> +{
> + unsigned is_elf64;
> +
> + /* Return. Ordered list of all object mappings sorted in
> + ascending order by VADDR. Must be freed with free_mapping_entry. */
> + VEC (mapping_entry_s) *list;
> +};
> +
> +static linux_find_memory_region_ftype find_memory_region_callback;
> +
> +/* Read .note.gnu.build-id from PT_NOTE. */
It is NT_GNU_BUILD_ID note from PT_NOTE segment.
.note.gnu.build-id is section name, PT_NOTE is segment name. Those do not
match.
> +
> +static void
> +read_build_id (struct find_memory_region_callback_data *const p,
> + mapping_entry_s *const bil, const CORE_ADDR load_addr,
> + const CORE_ADDR l_addr)
> +{
> + union ElfXX_Ehdr
> + {
> + Elf32_Ehdr _32;
> + Elf64_Ehdr _64;
> + } ehdr;
> + union ElfXX_Phdr
> + {
> + Elf32_Phdr _32;
> + Elf64_Phdr _64;
> + } const *phdr;
> + union ElfXX_Nhdr
> + {
> + Elf32_Nhdr _32;
> + Elf64_Nhdr _64;
> + } *nhdr;
> +#define HDR(hdr, fld) (((p)->is_elf64)? (hdr)._64.fld : (hdr)._32.fld)
> +#define SIZEOFHDR(hdr) (((p)->is_elf64)?sizeof((hdr)._64):sizeof((hdr)._32))
These macros are already defined above, use only one definition. It would be
appropriate to make their name slightly longer in such case, not required.
> + if (linux_read_memory (load_addr, (unsigned char *) &ehdr, SIZEOFHDR (ehdr))
> + == 0
> + && HDR (ehdr, e_ident[EI_MAG0]) == ELFMAG0
> + && HDR (ehdr, e_ident[EI_MAG1]) == ELFMAG1
> + && HDR (ehdr, e_ident[EI_MAG2]) == ELFMAG2
> + && HDR (ehdr, e_ident[EI_MAG3]) == ELFMAG3)
> + {
> + void *phdr_buf;
> + const ULONGEST p_type = PT_NOTE;
> +
> + gdb_assert (HDR (ehdr, e_phnum) < 100); /* Basic sanity check. */
> + gdb_assert (HDR (ehdr, e_phentsize) == SIZEOFHDR (*phdr));
> + phdr_buf = alloca (HDR (ehdr, e_phnum) * HDR (ehdr, e_phentsize));
> +
> + if (linux_read_memory (load_addr + HDR (ehdr, e_phoff), phdr_buf,
> + HDR (ehdr, e_phnum) * HDR (ehdr, e_phentsize))
> + != 0)
> + {
> + warning ("Could not read program header.");
> + return;
> + }
> +
> + phdr = phdr_buf;
> +
> + while ((phdr = find_phdr (p->is_elf64, phdr, (char *) phdr_buf
> + + HDR (ehdr, e_phnum) * HDR (ehdr, e_phentsize),
> + find_phdr_p, &p_type)) != NULL)
phdr_buf is void * and GDB codebase allows void * arithmetics so the cast
could be removed.
find_phdr_p probably should not be passed, as discussed above.
Assignment needs to be on a separate line according to GNU Coding Standards,
therefore:
for (;;)
{
phdr = find_phdr (p->is_elf64, phdr,
(phdr_buf
+ HDR (ehdr, e_phnum) * HDR (ehdr, e_phentsize)),
find_phdr_p, &p_type);
if (phdr == NULL)
break;
> + {
> + void *const pt_note = xmalloc (HDR (*phdr, p_memsz));
> + const void *const pt_end
> + = (char*) pt_note + HDR (*phdr, p_memsz);
When it does not fit on a single line use separate declaration line:
const void *pt_end;
pt_end = (gdb_byte *) pt_note + HDR (*phdr, p_memsz);
And also you use 'char' for byte but GDB - even with recent Pedro's changes
- prefers to use gdb_byte in such case. It is not a printable character.
> +
> + if (linux_read_memory (HDR (*phdr, p_vaddr) + l_addr,
> + pt_note, HDR (*phdr, p_memsz)) != 0)
> + {
> + xfree (pt_note);
> + warning ("Could not read note.");
> + break;
> + }
> +
> + nhdr = pt_note;
> + while ((void *) nhdr < pt_end)
> + {
> + const size_t note_sz
> + = HDR (*nhdr, n_namesz) + HDR (*nhdr, n_descsz)
> + + SIZEOFHDR (*nhdr);
Again it is more readable if split, also please keep the order as present in
the file:
const size_t note_sz;
note_sz = (SIZEOFHDR (*nhdr) + HDR (*nhdr, n_namesz)
+ HDR (*nhdr, n_descsz));
But there is also missing alignment to 4 bytes of both n_namesz and n_descsz:
Padding is present, if necessary, to ensure 4-byte alignment for the
descriptor. Such padding is not included in namesz.
+
Padding is present, if necessary, to ensure 4-byte alignment for the
next note entry. Such padding is not included in descsz.
> +
> + if (((char *) nhdr + note_sz) > (char *) pt_end)
gdb_byte *
And I asked for checking NOTE_SZ == 0 but you still do not check it. If there
will be NOTE_SZ == 0 then bin2hex below will use the code path:
/* May use a length, or a nul-terminated string as input. */
if (count == 0)
count = strlen ((char *) bin);
which may in a worst case even crash GDB on invalid file running out through
non-zero bytes out of mapped memory.
> + {
> + warning ("Malformed PT_NOTE\n");
> + break;
> + }
You need to check here also the name content, it is "GNU\x00" (n_namesz == 4).
> + if (HDR (*nhdr, n_type) == NT_GNU_BUILD_ID)
> + {
> + bil->hex_build_id = xmalloc (note_sz * 2 + 1);
> + bin2hex ((gdb_byte*) nhdr, bil->hex_build_id, note_sz);
I wrote last time:
GNU Coding Standard formatting:
bin2hex ((gdb_byte *) nhdr, bil->hex_build_id, note_sz);
But this is not the build-id.
readelf -n
Build ID: 1dfca42f0dac568cf81fedc2a9a37a98789a03e4
vs. gdbserver:
<library name="/lib64/ld-linux-x86-64.so.2" lm="0x7ffff7ffd998" l_addr="0x7ffff7ddc000" l_ld="0x7ffff7ffcdf0" build-id="040000001400000003000000474e55001dfca42f0dac568cf81fedc2a9a37a98789a03e4"/>
You need to send only the real build-id bytes, omitting the note header and the
note name ("GNU\0").
Then it will not match GDB itself, it also needs to be updated to process only
the build-id bytes, not the header.
> + xfree (pt_note);
> + return;
> + }
> + nhdr = (void*) ((char *) nhdr + note_sz);
I wrote last time:
GNU Coding Standard formatting + simplification:
nhdr = (void *) nhdr + note_sz;
> + }
> + xfree (pt_note);
> + }
> + }
> + else
> + warning ("Reading build-id failed.");
I would omit these warnings. But otherwise please put there some better
identifiers, such as vaddr and/or filename. Seeing just many such errors is
not too useful as I have found during the debugging today.
> +#undef HDR
> +#undef SIZEOFHDR
> +}
> +
> +
> +/* Add mapping_entry. */
> +
> +static int
> +find_memory_region_callback (ULONGEST vaddr, ULONGEST size, ULONGEST offset,
> + ULONGEST inode, int read, int write, int exec,
> + int modified, const char *filename, void *data)
> +{
> + if (inode != 0)
> + {
> + struct find_memory_region_callback_data *const p = data;
> + mapping_entry_s bil;
> +
> + bil.vaddr = vaddr;
> + bil.size = size;
> + bil.offset = offset;
> + bil.inode = inode;
> + bil.hex_build_id = NULL;
> +
> + VEC_safe_push (mapping_entry_s, p->list, &bil);
> + }
> +
> + /* Continue the traversal. */
> + return 0;
> +}
> +
> +/* Linear reverse find starting from RBEGIN towards REND looking for
> + the lowest vaddr mapping of the same inode and zero offset. */
> +
> +static mapping_entry_s *
> +lrfind_mapping_entry (mapping_entry_s *const rbegin,
> + const mapping_entry_s *const rend)
> +{
> + mapping_entry_s *p;
> +
> + for (p = rbegin - 1; p >= rend && p->inode == rbegin->inode; --p)
> + if (p->offset == 0)
> + return p;
I had here this layout:
7ffff7ddc000-7ffff7dfd000 r-xp 00000000 fd:01 51415762 /usr/lib64/ld-2.17.so
7ffff7ff9000-7ffff7ffa000 rw-p 00000000 00:00 0
7ffff7ffa000-7ffff7ffc000 r-xp 00000000 00:00 0 [vdso]
7ffff7ffc000-7ffff7ffe000 rw-p 00020000 fd:01 51415762 /usr/lib64/ld-2.17.so
so it should rather be:
for (p = rbegin - 1; p >= rend; --p)
if (p->offset == 0 && p->inode == rbegin->inode)
return p;
Fortunately it should not have any real performance impact.
> +
> + return NULL;
> +}
> +
> +/* Get build-id for the given L_LD. DATA must point to
> + already filled list of mapping_entry elements.
> +
> + Return build_id as stored in the list element corresponding
> + to L_LD.
> +
> + NULL may be returned if build-id could not be fetched.
> +
> + Returned string must not be freed explicitly. */
> +
> +static const char *
> +get_hex_build_id (const CORE_ADDR l_addr, const CORE_ADDR l_ld,
> + struct find_memory_region_callback_data *const data)
> +{
> + mapping_entry_s *bil;
> +
> + if (VEC_address (mapping_entry_s, data->list) == NULL)
> + return NULL;
> +
> + bil = bsearch (&l_ld, VEC_address (mapping_entry_s, data->list),
> + VEC_length (mapping_entry_s, data->list),
> + sizeof (mapping_entry_s), compare_mapping_entry_range);
> +
> + if (bil == NULL)
> + return NULL;
> +
> + if (bil->hex_build_id == NULL)
> + {
> + CORE_ADDR load_addr;
This variable declaration should be moved to the more inner block below.
> + mapping_entry_s *const bil_min
> + = lrfind_mapping_entry (bil,
> + VEC_address (mapping_entry_s, data->list));
When it does not fit the line make the declaration separate, such as:
mapping_entry_s *const bil_min;
bil_min = lrfind_mapping_entry (bil, VEC_address (mapping_entry_s,
data->list));
There should be an empty line between declarations and code statements.
> + if (bil_min != NULL)
> + {
> + load_addr = bil_min->vaddr;
> + read_build_id (data, bil, load_addr, l_addr);
> + }
> + else
> + {
> + /* Do not try to find hex_build_id again. */
> + bil->hex_build_id = xstrdup ("");
> + warning ("Could not determine load address; "
> + "build_id can not be used.");
build-id
The name of the feature is "build-id" so it always should be presented this
way to the user. Variable names are not interesting to users.
> + }
> + }
> +
> + return bil->hex_build_id;
> +}
> +
> /* Construct qXfer:libraries-svr4:read reply. */
>
> static int
> @@ -5653,6 +5975,7 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
> struct process_info_private *const priv = current_process ()->private;
> char filename[PATH_MAX];
> int pid, is_elf64;
> + struct find_memory_region_callback_data data;
>
> static const struct link_map_offsets lmo_32bit_offsets =
> {
> @@ -5688,6 +6011,14 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
> is_elf64 = elf_64_file_p (filename, &machine);
> lmo = is_elf64 ? &lmo_64bit_offsets : &lmo_32bit_offsets;
>
> + data.is_elf64 = is_elf64;
> + data.list = NULL;
> + VEC_reserve (mapping_entry_s, data.list, 16);
> + if (linux_find_memory_regions_full (
There should not be opening paren at the end.
> + lwpid_of (get_thread_lwp (current_inferior)),
When the parameters are too long for proper indentation use a temporary
variable for the value.
> + find_memory_region_callback, &data, NULL) < 0)
> + warning ("Finding memory regions failed");
> +
> if (priv->r_debug == 0)
> priv->r_debug = get_r_debug (pid, is_elf64);
>
> @@ -5762,6 +6093,7 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
> /* 6x the size for xml_escape_text below. */
> size_t len = 6 * strlen ((char *) libname);
> char *name;
> + const char *hex_enc_build_id = NULL;
>
> if (!header_done)
> {
> @@ -5770,21 +6102,28 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
> header_done = 1;
> }
>
> - while (allocated < p - document + len + 200)
> + name = xml_escape_text ((char *) libname);
> + hex_enc_build_id = get_hex_build_id (l_addr, l_ld, &data);
> +
> + while (allocated < (p - document + len + 200
> + + (hex_enc_build_id != NULL
> + ? strlen (hex_enc_build_id) : 0)))
> {
> /* Expand to guarantee sufficient storage. */
> - uintptr_t document_len = p - document;
> + const ptrdiff_t document_len = p - document;
>
> - document = xrealloc (document, 2 * allocated);
> allocated *= 2;
> + document = xrealloc (document, allocated);
> p = document + document_len;
> }
>
> - name = xml_escape_text ((char *) libname);
> p += sprintf (p, "<library name=\"%s\" lm=\"0x%lx\" "
> - "l_addr=\"0x%lx\" l_ld=\"0x%lx\"/>",
> + "l_addr=\"0x%lx\" l_ld=\"0x%lx\"",
> name, (unsigned long) lm_addr,
> (unsigned long) l_addr, (unsigned long) l_ld);
> + if (hex_enc_build_id != NULL)
> + p += sprintf (p, " build-id=\"%s\"", hex_enc_build_id);
> + p += sprintf(p, "/>");
> free (name);
> }
> else if (lm_prev == 0)
> @@ -5819,6 +6158,7 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
>
> memcpy (readbuf, document + offset, len);
> xfree (document);
> + free_mapping_entry (data.list);
>
> return len;
> }
> --
> 1.7.10.4
>
Thanks,
Jan