tools/perf: Add text_end to "struct dso" to save .text section size

Update "struct dso" to include new member "text_end".
This new field will represent the offset for end of text
section for a dso. For elf, this value is derived as:
sh_size (Size of section in byes) + sh_offset (Section file
offst) of the elf header for text.

For bfd, this value is derived as:
1. For PE file,
section->size + ( section->vma - dso->text_offset)
2. Other cases:
section->filepos (file position) + section->size (size of
section)

To resolve the address from a sample, perf looks at the
DSO maps. In case of address from a kernel module, there
were some address found to be not resolved. This was
observed while running perf test for "Object code reading".
Though the ip falls beteen the start address of the loaded
module (perf map->start ) and end address ( perf map->end),
it was unresolved.

Example:

    Reading object code for memory address: 0xc008000007f0142c
    File is: /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
    On file address is: 0x1114cc
    Objdump command is: objdump -z -d --start-address=0x11142c --stop-address=0x1114ac /lib/modules/6.5.0-rc3+/kernel/fs/xfs/xfs.ko
    objdump read too few bytes: 128
    test child finished with -1

Here, module is loaded at:
    # cat /proc/modules | grep xfs
    xfs 2228224 3 - Live 0xc008000007d00000

From objdump for xfs module, text section is:
    text 0010f7bc  0000000000000000 0000000000000000 000000a0 2**4

Here the offset for 0xc008000007f0142c ie  0x112074 falls out
.text section which is up to 0x10f7bc.

In this case for module, the address 0xc008000007e11fd4 is pointing
to stub instructions. This address range represents the module stubs
which is allocated on module load and hence is not part of DSO offset.

To identify such  address, which falls out of text
section and within module end, added the new field "text_end" to
"struct dso".

Reported-by: Disha Goel <disgoel@linux.ibm.com>
Signed-off-by: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Reviewed-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Kajol Jain <kjain@linux.ibm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: maddy@linux.ibm.com
Cc: disgoel@linux.vnet.ibm.com
Cc: linuxppc-dev@lists.ozlabs.org
Link: https://lore.kernel.org/r/20230928075213.84392-1-atrajeev@linux.vnet.ibm.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

diff --git a/tools/perf/util/dso.h b/tools/perf/util/dso.h
index b41c9782c754ee3ccafd99f74a18651306fd212d..70fe0fe69bef1df9c580659569d351d7a302c402 100644 (file)
--- a/tools/perf/util/dso.h
+++ b/tools/perf/util/dso.h
@@ -181,6 +181,7 @@ struct dso {
        u8               rel;
        struct build_id  bid;
        u64              text_offset;
+       u64              text_end;
        const char       *short_name;
        const char       *long_name;
        u16              long_name_len;

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 95e99c332d7e3f3104c4003ddd5b8cccefbc2cf1..9e7eeaf616b866894665eef45242beb71d6485c6 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -1514,8 +1514,10 @@ dso__load_sym_internal(struct dso *dso, struct map *map, struct symsrc *syms_ss,
        }
 
        if (elf_section_by_name(runtime_ss->elf, &runtime_ss->ehdr, &tshdr,
-                               ".text", NULL))
+                               ".text", NULL)) {
                dso->text_offset = tshdr.sh_addr - tshdr.sh_offset;
+               dso->text_end = tshdr.sh_offset + tshdr.sh_size;
+       }
 
        if (runtime_ss->opdsec)
                opddata = elf_rawdata(runtime_ss->opdsec, NULL);

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 5b54d2639df4740ead32fb860bba4c26635bcb69..2740d4457c13ad0cdc3cb62b0a49f280cb21e480 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1732,8 +1732,10 @@ int dso__load_bfd_symbols(struct dso *dso, const char *debugfile)
                        /* PE symbols can only have 4 bytes, so use .text high bits */
                        dso->text_offset = section->vma - (u32)section->vma;
                        dso->text_offset += (u32)bfd_asymbol_value(symbols[i]);
+                       dso->text_end = (section->vma - dso->text_offset) + section->size;
                } else {
                        dso->text_offset = section->vma - section->filepos;
+                       dso->text_end = section->filepos + section->size;
                }
        }