[v4,2/3] scripts/localplt.awk: Handle DT_JMPREL with empty PLT (for C-SKY)
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Commit Message
On csky-linux-gnuabiv2, binutils 2.33 produces a DT_JMPREL entry
for the dynamic loader if it does not contain any PLT relocations:
Dynamic section at offset 0x1df48 contains 19 entries:
Tag Type Name/Value
0x0000000e (SONAME) Library soname: [ld-linux-cskyv2-hf.so.1]
0x00000004 (HASH) 0xd4
0x6ffffef5 (GNU_HASH) 0x1a8
0x00000005 (STRTAB) 0x4ac
0x00000006 (SYMTAB) 0x28c
0x0000000a (STRSZ) 527 (bytes)
0x0000000b (SYMENT) 16 (bytes)
0x00000003 (PLTGOT) 0x1f000
0x00000002 (PLTRELSZ) 0 (bytes)
0x00000014 (PLTREL) RELA
0x00000017 (JMPREL) 0xaa4
0x00000007 (RELA) 0x75c
0x00000008 (RELASZ) 840 (bytes)
0x00000009 (RELAENT) 12 (bytes)
0x6ffffffc (VERDEF) 0x700
0x6ffffffd (VERDEFNUM) 3
0x6ffffff0 (VERSYM) 0x6bc
0x6ffffff9 (RELACOUNT) 68
0x00000000 (NULL) 0x0
This confuses the script:
Unexpected output from check-localplt: …/elf/ld.so.jmprel:
*** DT_JMPREL does not match any section's address
This commit changes the script to record the DT_PLTRELSZ value and
reject DT_JMPREL values not a section boundary only if DT_PLTRELSZ
is present with a non-zero value.
---
scripts/localplt.awk | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
Comments
On 2022-08-29 08:26, Florian Weimer via Libc-alpha wrote:
> On csky-linux-gnuabiv2, binutils 2.33 produces a DT_JMPREL entry
> for the dynamic loader if it does not contain any PLT relocations:
>
> Dynamic section at offset 0x1df48 contains 19 entries:
> Tag Type Name/Value
> 0x0000000e (SONAME) Library soname: [ld-linux-cskyv2-hf.so.1]
> 0x00000004 (HASH) 0xd4
> 0x6ffffef5 (GNU_HASH) 0x1a8
> 0x00000005 (STRTAB) 0x4ac
> 0x00000006 (SYMTAB) 0x28c
> 0x0000000a (STRSZ) 527 (bytes)
> 0x0000000b (SYMENT) 16 (bytes)
> 0x00000003 (PLTGOT) 0x1f000
> 0x00000002 (PLTRELSZ) 0 (bytes)
> 0x00000014 (PLTREL) RELA
> 0x00000017 (JMPREL) 0xaa4
> 0x00000007 (RELA) 0x75c
> 0x00000008 (RELASZ) 840 (bytes)
> 0x00000009 (RELAENT) 12 (bytes)
> 0x6ffffffc (VERDEF) 0x700
> 0x6ffffffd (VERDEFNUM) 3
> 0x6ffffff0 (VERSYM) 0x6bc
> 0x6ffffff9 (RELACOUNT) 68
> 0x00000000 (NULL) 0x0
>
> This confuses the script:
>
> Unexpected output from check-localplt: …/elf/ld.so.jmprel:
> *** DT_JMPREL does not match any section's address
>
> This commit changes the script to record the DT_PLTRELSZ value and
> reject DT_JMPREL values not a section boundary only if DT_PLTRELSZ
> is present with a non-zero value.
> ---
> scripts/localplt.awk | 18 +++++++++++++++---
> 1 file changed, 15 insertions(+), 3 deletions(-)
LGTM.
Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>
>
> diff --git a/scripts/localplt.awk b/scripts/localplt.awk
> index beaa342922..fe79ca01ab 100644
> --- a/scripts/localplt.awk
> +++ b/scripts/localplt.awk
> @@ -4,17 +4,25 @@
> # It writes "NAME: SYMBOL" for each PLT entry in NAME that refers to a
> # symbol defined in the same object.
>
> -BEGIN { result = 0 }
> +BEGIN {
> + result = 0;
> + pltrelsize = -1;
> +}
>
> FILENAME != lastfile {
> if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) {
> print FILENAME ": *** failed to find expected output (readelf -WSdr)";
> result = 2;
> }
> + if (pltrelsz > 0 && jmprel_offset == -1) {
> + print FILENAME ": Could not find section for DT_JMPREL";
> + result = 2;
> + }
> lastfile = FILENAME;
> jmprel_offset = 0;
> rela_offset = 0;
> rel_offset = 0;
> + pltrelsz = -1;
> delete section_offset_by_address;
> }
>
> @@ -82,12 +90,16 @@ $2 == "(JMPREL)" {
> if (jmprel_addr in section_offset_by_address) {
> jmprel_offset = section_offset_by_address[jmprel_addr];
> } else {
> - print FILENAME ": *** DT_JMPREL does not match any section's address";
> - result = 2;
> + jmprel_offset = -1
> }
> next
> }
>
> +$2 == "(PLTRELSZ)" {
> + pltrelsz = strtonum($3);
> + next
> +}
> +
> $2 == "(RELA)" {
> rela_addr = strtonum($3);
> if (rela_addr in section_offset_by_address) {
@@ -4,17 +4,25 @@
# It writes "NAME: SYMBOL" for each PLT entry in NAME that refers to a
# symbol defined in the same object.
-BEGIN { result = 0 }
+BEGIN {
+ result = 0;
+ pltrelsize = -1;
+}
FILENAME != lastfile {
if (lastfile && jmprel_offset == 0 && rela_offset == 0 && rel_offset == 0) {
print FILENAME ": *** failed to find expected output (readelf -WSdr)";
result = 2;
}
+ if (pltrelsz > 0 && jmprel_offset == -1) {
+ print FILENAME ": Could not find section for DT_JMPREL";
+ result = 2;
+ }
lastfile = FILENAME;
jmprel_offset = 0;
rela_offset = 0;
rel_offset = 0;
+ pltrelsz = -1;
delete section_offset_by_address;
}
@@ -82,12 +90,16 @@ $2 == "(JMPREL)" {
if (jmprel_addr in section_offset_by_address) {
jmprel_offset = section_offset_by_address[jmprel_addr];
} else {
- print FILENAME ": *** DT_JMPREL does not match any section's address";
- result = 2;
+ jmprel_offset = -1
}
next
}
+$2 == "(PLTRELSZ)" {
+ pltrelsz = strtonum($3);
+ next
+}
+
$2 == "(RELA)" {
rela_addr = strtonum($3);
if (rela_addr in section_offset_by_address) {