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Re: time to workaround libc/13097 in fsf gdb?
- From: Pedro Alves <palves at redhat dot com>
- To: Jan Kratochvil <jan dot kratochvil at redhat dot com>
- Cc: Doug Evans <xdje42 at gmail dot com>, "gdb-patches at sourceware dot org" <gdb-patches at sourceware dot org>
- Date: Fri, 26 Sep 2014 13:05:27 +0100
- Subject: Re: time to workaround libc/13097 in fsf gdb?
- Authentication-results: sourceware.org; auth=none
- References: <20140922183505 dot GA21660 at host2 dot jankratochvil dot net>
On 09/22/2014 07:35 PM, Jan Kratochvil wrote:
> Yes, it works for me on kernel-2.6.32-220.el6.x86_64 (also verified your
> previous patch still displayed the warning).
Thanks for the testing.
>> --- a/gdb/gdbarch.sh
>> +++ b/gdb/gdbarch.sh
>> @@ -1029,6 +1029,10 @@ m:int:insn_is_jump:CORE_ADDR addr:addr::default_insn_is_jump::0
>> # Return -1 if there is insufficient buffer for a whole entry.
>> # Return 1 if an entry was read into *TYPEP and *VALP.
>> M:int:auxv_parse:gdb_byte **readptr, gdb_byte *endptr, CORE_ADDR *typep, CORE_ADDR *valp:readptr, endptr, typep, valp
>> +# Find the address range of the current inferior's vsyscall/vDSO, and
>> +# write it to *START, *END. Returns true if found, false otherwise.
> I find unclear the description whether *END is the last byte address or the
> after-the-last byte address.
OK. Best just use "struct mem_range" instead and avoid this
ambiguity whenever we need a range. That struct uses "int" for
length. Although that should be fixed, that can be done
independently. int is obviously sufficient for the vDSO.
>> +/* Arguments for symbol_file_add_from_memory_wrapper. */
>> +struct find_mapping_size_args
>> + CORE_ADDR vaddr;
>> + size_t size;
> size_t and not CORE_ADDR? (This patch uses also unsigned long for this value.)
I assume you means ULONGEST or some such. But, I just moved that
code (and renamed it). IIRC, it's size_t because that's what the
"bfd from remote memory" interface uses. This structure disappears in
the next version. We can work with struct mem_range here too.
>> +static int
>> +linux_vsyscall_range (struct gdbarch *gdbarch, CORE_ADDR *start, CORE_ADDR *end)
>> + struct find_mapping_size_args args;
>> + if (target_auxv_search (¤t_target, AT_SYSINFO_EHDR, &args.vaddr) <= 0)
>> + return 0;
>> + /* This is installed by linux_init_abi below, so should always be
>> + available. */
>> + gdb_assert (gdbarch_find_memory_regions_p (target_gdbarch ()));
> Is there a reason for target_gdbarch () and not gdbarch?
>> + args.size = 0;
>> + gdbarch_find_memory_regions (target_gdbarch (),
>> + find_mapping_size, &args);
>> + *start = args.vaddr;
>> + *end = *start + args.size;
>> + return 1;
> Here it returns 1 even if the vDSO was not found.
> It will return *start == *end so the current only caller behaves correctly.
> But I do not find it fully compliant to its gdbarch.sh documentation.
Yeah. The next version will make that clear in the documentation.
>> static void
>> add_vsyscall_page (struct target_ops *target, int from_tty)
>> - CORE_ADDR sysinfo_ehdr;
>> + CORE_ADDR vsyscall_start, vsyscall_end;
>> - if (target_auxv_search (target, AT_SYSINFO_EHDR, &sysinfo_ehdr) > 0
>> - && sysinfo_ehdr != (CORE_ADDR) 0)
>> + if (gdbarch_vsyscall_range (target_gdbarch (),
>> + &vsyscall_start, &vsyscall_end))
> This is a code cleanup part of the patch which could be separate.
OK. The next version splits this out to a preparatory patch.
Thanks. I'll be posting the new series in a bit.