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perf tools: Fix copying of /proc/kcore 

A copy of /proc/kcore containing the kernel text can be made to the
buildid cache. e.g.

	perf buildid-cache -v -k /proc/kcore

To workaround objdump limitations, a copy is also made when annotating
against /proc/kcore.

The copying process stops working from libelf about v1.62 onwards (the
problem was found with v1.63).

The cause is that a call to gelf_getphdr() in kcore__add_phdr() fails
because additional validation has been added to gelf_getphdr().

The use of gelf_getphdr() is a misguided attempt to get default
initialization of the Gelf_Phdr structure.  That should not be
necessary because every member of the Gelf_Phdr structure is
subsequently assigned.  So just remove the call to gelf_getphdr().

Similarly, a call to gelf_getehdr() in gelf_kcore__init() can be
removed also.

Committer notes:

Note to stable@kernel.org, from Adrian in the cover letter for this
patchkit:

The "Fix copying of /proc/kcore" problem goes back to v3.13 if you think
it is important enough for stable.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1443089122-19082-3-git-send-email-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Adrian Hunter 2015-09-24 13:05:22 +03:00 committed by Arnaldo Carvalho de Melo
parent 597ee40722
commit b5cabbcbd1
1 changed files with 12 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
tools/perf/util/symbol-elf.c
View File

@ -1271,8 +1271,6 @@ static int kcore__open(struct kcore *kcore, const char *filename)
static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
bool temp)
{
GElf_Ehdr *ehdr;
kcore->elfclass = elfclass;
if (temp)
@ -1289,9 +1287,7 @@ static int kcore__init(struct kcore *kcore, char *filename, int elfclass,
if (!gelf_newehdr(kcore->elf, elfclass))
goto out_end;
ehdr = gelf_getehdr(kcore->elf, &kcore->ehdr);
if (!ehdr)
goto out_end;
memset(&kcore->ehdr, 0, sizeof(GElf_Ehdr));
return 0;
@ -1348,23 +1344,18 @@ static int kcore__copy_hdr(struct kcore *from, struct kcore *to, size_t count)
static int kcore__add_phdr(struct kcore *kcore, int idx, off_t offset,
u64 addr, u64 len)
{
GElf_Phdr gphdr;
GElf_Phdr *phdr;
GElf_Phdr phdr = {
.p_type = PT_LOAD,
.p_flags = PF_R | PF_W | PF_X,
.p_offset = offset,
.p_vaddr = addr,
.p_paddr = 0,
.p_filesz = len,
.p_memsz = len,
.p_align = page_size,
};
phdr = gelf_getphdr(kcore->elf, idx, &gphdr);
if (!phdr)
return -1;
phdr->p_type = PT_LOAD;
phdr->p_flags = PF_R | PF_W | PF_X;
phdr->p_offset = offset;
phdr->p_vaddr = addr;
phdr->p_paddr = 0;
phdr->p_filesz = len;
phdr->p_memsz = len;
phdr->p_align = page_size;
if (!gelf_update_phdr(kcore->elf, idx, phdr))
if (!gelf_update_phdr(kcore->elf, idx, &phdr))
return -1;
return 0;