[Valgrind-developers] [valgrind] riscv64: Add hardwire for ld-linux-riscv64-lp64d.so.1 strcmp

[Mark W. <ma...@so...>]

https://sourceware.org/git/gitweb.cgi?p=valgrind.git;h=2d09ef48e22061b143cd4765e8defb63f5d5024a

commit 2d09ef48e22061b143cd4765e8defb63f5d5024a
Author: Mark Wielaard <ma...@kl...>
Date:   Sat Dec 28 01:29:58 2024 +0100

    riscv64: Add hardwire for ld-linux-riscv64-lp64d.so.1 strcmp
    
    When using dlopen ld.so can end up in glibc strcmp_unaligned_loop
    which causes undefined reads. Hardwire strcmp for ld.so with a simple
    assembly implementation.

Diff:
---
 coregrind/m_redir.c             |  5 +++++
 coregrind/m_trampoline.S        | 17 +++++++++++++++++
 coregrind/pub_core_trampoline.h |  1 +
 3 files changed, 23 insertions(+)

diff --git a/coregrind/m_redir.c b/coregrind/m_redir.c
index 958f3e7c46..5e7bc42f97 100644
--- a/coregrind/m_redir.c
+++ b/coregrind/m_redir.c
@@ -1714,6 +1714,11 @@ void VG_(redir_initialise) ( void )
          (Addr)&VG_(riscv64_linux_REDIR_FOR_index),
          complain_about_stripped_glibc_ldso
       );
+      add_hardwired_spec(
+         "ld-linux-riscv64-lp64d.so.1", "strcmp",
+         (Addr)&VG_(riscv64_linux_REDIR_FOR_strcmp),
+         complain_about_stripped_glibc_ldso
+      );
    }
 
 #  elif defined(VGP_x86_solaris)
diff --git a/coregrind/m_trampoline.S b/coregrind/m_trampoline.S
index c506070d6a..4860a2259f 100644
--- a/coregrind/m_trampoline.S
+++ b/coregrind/m_trampoline.S
@@ -1647,6 +1647,23 @@ VG_(riscv64_linux_REDIR_FOR_index):
 	ret
 .size VG_(riscv64_linux_REDIR_FOR_index), .-VG_(riscv64_linux_REDIR_FOR_index)
 
+.global VG_(riscv64_linux_REDIR_FOR_strcmp)
+.type   VG_(riscv64_linux_REDIR_FOR_strcmp), @function
+VG_(riscv64_linux_REDIR_FOR_strcmp):
+0:
+	lbu a5, 0(a0)          /* load *s1 */
+	lbu a4, 0(a1)          /* load *s2 */
+	beqz a5, 1f            /* check end of s1 */
+	beq a5, a4, 2f         /* loop if *s1 == *s2 */
+1:
+	subw a0, a5, a4        /* return value is *s1 - *s2 */
+	ret
+2:
+	addi a0, a0, 1         /* next char in s1 */
+	addi a1, a1, 1         /* next char in s2 */
+        j 0b                   /* and back to the start */
+.size VG_(riscv64_linux_REDIR_FOR_strcmp), .-VG_(riscv64_linux_REDIR_FOR_strcmp)
+
 .global VG_(trampoline_stuff_end)
 VG_(trampoline_stuff_end):
 
diff --git a/coregrind/pub_core_trampoline.h b/coregrind/pub_core_trampoline.h
index 7e9e2d76be..db497c51a5 100644
--- a/coregrind/pub_core_trampoline.h
+++ b/coregrind/pub_core_trampoline.h
@@ -180,6 +180,7 @@ extern UInt  VG_(nanomips_linux_REDIR_FOR_strlen)( void* );
 extern Addr   VG_(riscv64_linux_SUBST_FOR_rt_sigreturn);
 extern HChar* VG_(riscv64_linux_REDIR_FOR_index)( const HChar*, Int );
 extern SizeT  VG_(riscv64_linux_REDIR_FOR_strlen)( const HChar* );
+extern Int    VG_(riscv64_linux_REDIR_FOR_strcmp)( const HChar*, const HChar* );
 #endif
 
 #if defined(VGP_x86_solaris)