I ran into this issue while trying to debug a _different_ issue witin
the uClinc(-ng) arc dynamic linker. I turned on debugging support
within the dynamic linker, and the linker would no longer complete its
bootstrap phase due to a lack of support for the R_ARC_JMP_SLOT
relocation type.
To reproduce this issue it should be enough to configure uClibc(-ng)
for ARC with 'DODEBUG=y', then try to run anything that requires
dynamic linking.
The R_ARC_JMP_SLOT relocation type is used within the .plt, so I
believe it makes sense for these relocations to be generated.
I updated the associated comment above the boostrap patching code so
that it makes more sense (to me at least) with the extra relocation
support.
I wonder if you would consider merging this patch?
Thanks,
Andrew
---
This commit adds support for R_ARC_JMP_SLOT relocations during the
bootstrap phase of the dynamic linker. These relocations will be
generated if uClibc is configured with 'DODEBUG=y'.
---
ldso/ldso/arc/dl-startup.h | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/ldso/ldso/arc/dl-startup.h b/ldso/ldso/arc/dl-startup.h
index ef89b53..fadc433 100644
--- a/ldso/ldso/arc/dl-startup.h
+++ b/ldso/ldso/arc/dl-startup.h
@@ -64,10 +64,11 @@ __asm__(
/*
* Dynamic loader bootstrapping:
- * Since we don't modify text at runtime, these can only be data relos
- * (so safe to assume that they are word aligned).
- * And also they HAVE to be RELATIVE relos only
- * @RELP is the relo entry being processed
+ * The only relocations that should be found are either R_ARC_RELATIVE for
+ * data relocations (.got, etc) or R_ARC_JMP_SLOT for code relocations
+ * (.plt). It is safe to assume that all of these relocations are word
+ * aligned.
+ * @RELP is the reloc entry being processed
* @REL is the pointer to the address we are relocating.
* @SYMBOL is the symbol involved in the relocation
* @LOAD is the load address.
@@ -78,6 +79,8 @@ do {
\
int type = ELF32_R_TYPE((RELP)->r_info); \
if (likely(type == R_ARC_RELATIVE)) \
*REL += (unsigned long) LOAD; \
+ else if (type == R_ARC_JMP_SLOT) \
+ *REL = SYMBOL; \
else \
_dl_exit(1); \
}while(0)
--
2.5.1
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