From: Fangrui Song <maskray@google.com>
To: libc-alpha@sourceware.org, Darius Rad <darius@bluespec.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: [PATCH] riscv: Fix incorrect jal with HIDDEN_JUMPTARGET
Date: Wed, 27 Oct 2021 23:50:19 -0700 [thread overview]
Message-ID: <20211028065019.3247061-1-maskray@google.com> (raw)
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.
---
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 0b92016b31..bec7ff80f4 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 9510518750..e44a68aad4 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)
--
2.33.0.1079.g6e70778dc9-goog
next reply other threads:[~2021-10-28 6:50 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-28 6:50 Fangrui Song [this message]
2021-10-28 13:31 ` Adhemerval Zanella
2021-10-28 18:05 ` Palmer Dabbelt
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