[glibc/maskray/relr] riscv: Fix incorrect jal with HIDDEN_JUMPTARGET

[glibc/maskray/relr] riscv: Fix incorrect jal with HIDDEN_JUMPTARGET

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=68389203832ab39dd0dbaabbc4059e7fff51c29b

commit 68389203832ab39dd0dbaabbc4059e7fff51c29b
Author: Fangrui Song <maskray@google.com>
Date:   Thu Oct 28 11:39:49 2021 -0700

    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>

Diff:
---
 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)