Bug 359733

This was suggested about a year ago in the Fosdem easy hacks presentation:
https://archive.fosdem.org/2015/schedule/event/valgrind_easy_hack/attachments/slides/731/export/events/attachments/valgrind_easy_hack/slides/731/valgrind_easy_hacks.html#slide16

The suppression and redirection isn't needed for x86. When testing a newer glibc or calling the ld.so through an alternative path neither the suppression (doesn't match path/name) nor the redirection (triggers too late) works. Since there is already an hardwire override for strlen in amd64 ld.so it makes sense to also hardware index (it is always called when ld.so loads the preload images)

Reproducible: Always




Suggested patch:

diff --git a/coregrind/m_redir.c b/coregrind/m_redir.c
index dcf1fb4..dae47f1 100644
--- a/coregrind/m_redir.c
+++ b/coregrind/m_redir.c
@@ -1353,6 +1353,9 @@ void VG_(redir_initialise) ( void )
    if (0==VG_(strcmp)("Memcheck", VG_(details).name)) {
 
       add_hardwired_spec(
+         "ld-linux-x86-64.so.2", "index",
+         (Addr)&VG_(amd64_linux_REDIR_FOR_index), NULL);
+      add_hardwired_spec(
          "ld-linux-x86-64.so.2", "strlen",
          (Addr)&VG_(amd64_linux_REDIR_FOR_strlen),
 #        ifndef GLIBC_MANDATORY_STRLEN_REDIRECT
diff --git a/coregrind/m_trampoline.S b/coregrind/m_trampoline.S
index cac2288..176ea66 100644
--- a/coregrind/m_trampoline.S
+++ b/coregrind/m_trampoline.S
@@ -220,6 +220,30 @@ VG_(amd64_linux_REDIR_FOR_strlen):
 .LfnE5:
 .size VG_(amd64_linux_REDIR_FOR_strlen), .-VG_(amd64_linux_REDIR_FOR_strlen)
 
+.global VG_(amd64_linux_REDIR_FOR_index)
+.type   VG_(amd64_linux_REDIR_FOR_index), @function
+VG_(amd64_linux_REDIR_FOR_index):
+        movzbl  (%rdi), %eax
+        movl    %esi, %edx
+        cmpb    %sil, %al
+        jne     .L4
+        jmp     .L5
+.L10:
+        addq    $1, %rdi
+        movzbl  (%rdi), %eax
+        cmpb    %dl, %al
+        je      .L5
+.L4:
+        testb   %al, %al
+        jne     .L10
+        xorl    %eax, %eax
+        ret
+.L5:
+        movq    %rdi, %rax
+        ret
+.size VG_(amd64_linux_REDIR_FOR_index), .-VG_(amd64_linux_REDIR_FOR_index)
+
+
 
 /* A CIE for the above four functions, followed by their FDEs */
 	.section .eh_frame,"a",@progbits
diff --git a/coregrind/pub_core_trampoline.h b/coregrind/pub_core_trampoline.h
index eda5ec6..1396519 100644
--- a/coregrind/pub_core_trampoline.h
+++ b/coregrind/pub_core_trampoline.h
@@ -71,6 +71,7 @@ extern Addr VG_(amd64_linux_REDIR_FOR_vgettimeofday);
 extern Addr VG_(amd64_linux_REDIR_FOR_vtime);
 extern Addr VG_(amd64_linux_REDIR_FOR_vgetcpu);
 extern UInt VG_(amd64_linux_REDIR_FOR_strlen)( void* );
+extern Char* VG_(amd64_linux_REDIR_FOR_index) ( const Char*, Int );
 #endif
 
 #if defined(VGP_ppc32_linux)
diff --git a/shared/vg_replace_strmem.c b/shared/vg_replace_strmem.c
index 005b679..8de085a 100644
--- a/shared/vg_replace_strmem.c
+++ b/shared/vg_replace_strmem.c
@@ -247,7 +247,7 @@ static inline void my_exit ( int x )
  STRCHR(VG_Z_LIBC_SONAME,          __strchr_sse2)
  STRCHR(VG_Z_LIBC_SONAME,          __strchr_sse2_no_bsf)
  STRCHR(VG_Z_LIBC_SONAME,          index)
-# if !defined(VGP_x86_linux)
+# if !defined(VGP_x86_linux) && !defined(VGP_amd64_linux)
   STRCHR(VG_Z_LD_LINUX_SO_2,        strchr)
   STRCHR(VG_Z_LD_LINUX_SO_2,        index)
   STRCHR(VG_Z_LD_LINUX_X86_64_SO_2, strchr)