lkml.org 
[lkml]   [2018]   [May]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH V3 17/17] perf buildid-cache: kcore_copy: Amend the offset of sections that remap kernel text
    Date
    x86 PTI entry trampolines all map to the same physical page. If that is
    reflected in the program headers of /proc/kcore, then do the same for the
    copy of kcore.

    Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
    ---
    tools/perf/util/symbol-elf.c | 53 ++++++++++++++++++++++++++++++++++++++++++--
    1 file changed, 51 insertions(+), 2 deletions(-)

    diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
    index 584966913aeb..29770ea61768 100644
    --- a/tools/perf/util/symbol-elf.c
    +++ b/tools/perf/util/symbol-elf.c
    @@ -1390,6 +1390,7 @@ struct phdr_data {
    u64 addr;
    u64 len;
    struct list_head node;
    + struct phdr_data *remaps;
    };

    struct sym_data {
    @@ -1597,16 +1598,62 @@ static int kcore_copy__read_maps(struct kcore_copy_info *kci, Elf *elf)
    return 0;
    }

    +static void kcore_copy__find_remaps(struct kcore_copy_info *kci)
    +{
    + struct phdr_data *p, *k = NULL;
    + u64 kend;
    +
    + if (!kci->stext)
    + return;
    +
    + /* Find phdr that corresponds to the kernel map (contains stext) */
    + kcore_copy__for_each_phdr(kci, p) {
    + u64 pend = p->addr + p->len - 1;
    +
    + if (p->addr <= kci->stext && pend >= kci->stext) {
    + k = p;
    + break;
    + }
    + }
    +
    + if (!k)
    + return;
    +
    + kend = k->offset + k->len;
    +
    + /* Find phdrs that remap the kernel */
    + kcore_copy__for_each_phdr(kci, p) {
    + u64 pend = p->offset + p->len;
    +
    + if (p == k)
    + continue;
    +
    + if (p->offset >= k->offset && pend <= kend)
    + p->remaps = k;
    + }
    +}
    +
    static void kcore_copy__layout(struct kcore_copy_info *kci)
    {
    struct phdr_data *p;
    off_t rel = 0;

    + kcore_copy__find_remaps(kci);
    +
    kcore_copy__for_each_phdr(kci, p) {
    - p->rel = rel;
    - rel += p->len;
    + if (!p->remaps) {
    + p->rel = rel;
    + rel += p->len;
    + }
    kci->phnum += 1;
    }
    +
    + kcore_copy__for_each_phdr(kci, p) {
    + struct phdr_data *k = p->remaps;
    +
    + if (k)
    + p->rel = p->offset - k->offset + k->rel;
    + }
    }

    static int kcore_copy__calc_maps(struct kcore_copy_info *kci, const char *dir,
    @@ -1821,6 +1868,8 @@ int kcore_copy(const char *from_dir, const char *to_dir)
    kcore_copy__for_each_phdr(&kci, p) {
    off_t offs = p->rel + offset;

    + if (p->remaps)
    + continue;
    if (copy_bytes(kcore.fd, p->offset, extract.fd, offs, p->len))
    goto out_extract_close;
    }
    --
    1.9.1
    \
     
     \ /
      Last update: 2018-05-22 12:58    [W:3.030 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site