Message ID | 20211028065019.3247061-1-maskray@google.com |
---|---|
State | New |
Headers | show |
Series | riscv: Fix incorrect jal with HIDDEN_JUMPTARGET | expand |
On 28/10/2021 03:50, Fangrui Song wrote: > 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. LGTM, thanks. I am testing a patch similar to this locally to make ldd build glibc. 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 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) >
On Wed, 27 Oct 2021 23:50:19 PDT (-0700), maskray@google.com wrote: > 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) Acked-by: Palmer Dabbelt <palmer@dabbelt.com> Thanks. Fangrui said he'd be able to commit this, which is fine with me.
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)