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Message-ID: <20260708131932.718636-1-alex@alexrp.com>
Date: Wed, 8 Jul 2026 15:19:32 +0200
From: Alex Rønne Petersen <alex@...xrp.com>
To: musl@...ts.openwall.com
Cc: Alex Rønne Petersen <alex@...xrp.com>
Subject: [PATCH v2] powerpc64: add nop after b/bl to fix power10 linking
Previously discussed in [0] and [1].
The proper fix here is to use b/bl sym@...oc. As noted in the previous threads,
it seems like the assembler really should be able to infer the @notoc in these
cases, but since LLVM's assembler doesn't in practice, we need to deal with it
somehow.
Unfortunately, binutils only gained support for @notoc in 2018, and lld in 2020.
I'm not sure that we want to take a hard dependency on toolchains that recent,
so simply adding the nop seems like the lesser evil to me, especially
considering these are not particularly hot code paths.
[0] https://www.openwall.com/lists/musl/2025/12/11/4
[1] https://www.openwall.com/lists/musl/2025/12/12/1
---
arch/powerpc64/crt_arch.h | 1 +
src/ldso/powerpc64/dlsym.s | 1 +
2 files changed, 2 insertions(+)
diff --git a/arch/powerpc64/crt_arch.h b/arch/powerpc64/crt_arch.h
index 168669a9..c3817def 100644
--- a/arch/powerpc64/crt_arch.h
+++ b/arch/powerpc64/crt_arch.h
@@ -13,6 +13,7 @@ START ": \n"
" stdu 0, -32(1) \n"
" mtlr 0 \n"
" bl " START "_c \n"
+" nop \n"
".weak _DYNAMIC \n"
".hidden _DYNAMIC \n"
"1: .long _DYNAMIC-" START "\n"
diff --git a/src/ldso/powerpc64/dlsym.s b/src/ldso/powerpc64/dlsym.s
index a14715fd..73e70db9 100644
--- a/src/ldso/powerpc64/dlsym.s
+++ b/src/ldso/powerpc64/dlsym.s
@@ -8,4 +8,5 @@ dlsym:
.localentry dlsym,.-dlsym
mflr 5 # The return address is arg3.
b __dlsym
+ nop
.size dlsym, .-dlsym
--
2.53.0
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