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From b88a116d880eebf8b0ff52146ddd5c8120d55545 Mon Sep 17 00:00:00 2001
Message-ID: <b88a116d880eebf8b0ff52146ddd5c8120d55545.1743754811.git.rsworktech@outlook.com>
From: Fangrui Song <maskray@google.com>
Date: Thu, 28 Oct 2021 11:39:49 -0700
Subject: [PATCH] riscv: Fix incorrect jal with HIDDEN_JUMPTARGET
A non-local STV_DEFAULT defined symbol is by default preemptible in a
shared object. j/jal cannot target a preemptible symbol. On other
architectures, such a jump instruction either causes PLT [BZ #18822], or
if short-ranged, sometimes rejected by the linker (but not by GNU ld's
riscv port [ld PR/28509]).
Use HIDDEN_JUMPTARGET to target a non-preemptible symbol instead.
With this patch, ld.so and libc.so can be linked with LLD if source
files are compiled/assembled with -mno-relax/-Wa,-mno-relax.
Acked-by: Palmer Dabbelt <palmer@dabbelt.com>
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---
sysdeps/riscv/setjmp.S | 2 +-
sysdeps/unix/sysv/linux/riscv/setcontext.S | 5 +++--
2 files changed, 4 insertions(+), 3 deletions(-)
diff --git a/sysdeps/riscv/setjmp.S b/sysdeps/riscv/setjmp.S
index 38a93b78e8..435e25d044 100644
--- a/sysdeps/riscv/setjmp.S
+++ b/sysdeps/riscv/setjmp.S
@@ -21,7 +21,7 @@
ENTRY (_setjmp)
li a1, 0
- j __sigsetjmp
+ j HIDDEN_JUMPTARGET (__sigsetjmp)
END (_setjmp)
ENTRY (setjmp)
li a1, 1
diff --git a/sysdeps/unix/sysv/linux/riscv/setcontext.S b/sysdeps/unix/sysv/linux/riscv/setcontext.S
index a494b100be..f0dce4fbad 100644
--- a/sysdeps/unix/sysv/linux/riscv/setcontext.S
+++ b/sysdeps/unix/sysv/linux/riscv/setcontext.S
@@ -95,6 +95,7 @@ LEAF (__setcontext)
99: j __syscall_error
END (__setcontext)
+libc_hidden_def (__setcontext)
weak_alias (__setcontext, setcontext)
LEAF (__start_context)
@@ -108,7 +109,7 @@ LEAF (__start_context)
/* Invoke subsequent context if present, else exit(0). */
mv a0, s2
beqz s2, 1f
- jal __setcontext
-1: j exit
+ jal HIDDEN_JUMPTARGET (__setcontext)
+1: j HIDDEN_JUMPTARGET (exit)
END (__start_context)
--
2.49.0
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