From 78fe3625f6b8ed4de28527d71c4a98d70e5b3035 Mon Sep 17 00:00:00 2001
From: Mark Wielaard <mark@klomp.org>
Date: Mon, 18 Aug 2025 15:30:47 +0200
Subject: [PATCH] Add ppc64le linux hardwire for ld64.so.2 strcmp

When dlopen is used we might end up in an assembly powerpc/strcmp.S
variant that is optimized in a way memcheck cannot proof correct. We
try to intercept strcmp in ld.so, but might fail when strcmp is called
before our interception code is loaded. Having an hardwire for ld.so
strcmp (earlier intercept) would solve this.

https://bugs.kde.org/show_bug.cgi?id=508145
---
 coregrind/m_redir.c             |  6 +++++
 coregrind/m_trampoline.S        | 45 +++++++++++++++++++++++++++++++++
 coregrind/pub_core_trampoline.h |  1 +
 3 files changed, 52 insertions(+)

diff --git a/coregrind/m_redir.c b/coregrind/m_redir.c
index 63172b971..857f910cb 100644
--- a/coregrind/m_redir.c
+++ b/coregrind/m_redir.c
@@ -1508,6 +1508,12 @@ void VG_(redir_initialise) ( void )
          NULL /* not mandatory - so why bother at all? */
          /* glibc-2.5 (FC6, ppc64) seems fine without it */
       );
+
+      add_hardwired_spec(
+         "ld64.so.2", "strcmp",
+         (Addr)&VG_(ppc64_linux_REDIR_FOR_strcmp),
+         NULL
+      );
    }
 
 #  elif defined(VGP_arm_linux)
diff --git a/coregrind/m_trampoline.S b/coregrind/m_trampoline.S
index 2c2cc0dc2..af25c8f7a 100644
--- a/coregrind/m_trampoline.S
+++ b/coregrind/m_trampoline.S
@@ -604,6 +604,51 @@ VG_(ppc64_linux_REDIR_FOR_strchr):
 .L1end:
 
 	
+	/* this function is written using the "dotless" ABI convention */
+	.align 2
+	.globl VG_(ppc64_linux_REDIR_FOR_strcmp)
+#if !defined VGP_ppc64be_linux || _CALL_ELF == 2
+        /* Little Endian uses ELF version 2 */
+        .type VG_(ppc64_linux_REDIR_FOR_strcmp),@function
+VG_(ppc64_linux_REDIR_FOR_strcmp):
+#else
+        /* Big Endian uses ELF version 1 */
+	.section        ".opd","aw"
+	.align 3
+VG_(ppc64_linux_REDIR_FOR_strcmp):
+	.quad   .L.VG_(ppc64_linux_REDIR_FOR_strcmp),.TOC.@tocbase,0
+	.previous
+	.size	VG_(ppc64_linux_REDIR_FOR_strcmp), \
+			.LFE0-.L.VG_(ppc64_linux_REDIR_FOR_strcmp)
+	.type	VG_(ppc64_linux_REDIR_FOR_strcmp), @function
+
+.L.VG_(ppc64_linux_REDIR_FOR_strcmp):
+#endif
+#if _CALL_ELF == 2
+0:      addis        2,12,.TOC.-0b@ha
+        addi         2,2,.TOC.-0b@l
+        .localentry  VG_(ppc64_linux_REDIR_FOR_strcmp), .-VG_(ppc64_linux_REDIR_FOR_strcmp)
+#endif
+.LFB0:
+        .cfi_startproc
+        li 10,0
+.L3:
+        lbzx 8,3,10
+        lbzx 9,4,10
+        cmpwi 0,8,0
+        beq 0,.L2
+        cmpw 0,8,9
+        addi 10,10,1
+        beq 0,.L3
+.L2:
+        subf 3,9,8
+        extsw 3,3
+        blr
+        .long 0
+        .byte 0,0,0,0,0,0,0,0
+        .cfi_endproc
+.LFE0:
+
 .global VG_(trampoline_stuff_end)
 VG_(trampoline_stuff_end):
 
diff --git a/coregrind/pub_core_trampoline.h b/coregrind/pub_core_trampoline.h
index 11d791df7..92b4fc67b 100644
--- a/coregrind/pub_core_trampoline.h
+++ b/coregrind/pub_core_trampoline.h
@@ -97,6 +97,7 @@ extern void* VG_(ppc32_linux_REDIR_FOR_strchr)( void*, Int );
 #if defined(VGP_ppc64be_linux) || defined(VGP_ppc64le_linux)
 extern Addr  VG_(ppc64_linux_SUBST_FOR_rt_sigreturn);
 extern UInt  VG_(ppc64_linux_REDIR_FOR_strlen)( void* );
+extern UInt  VG_(ppc64_linux_REDIR_FOR_strcmp)( void*, void* );
 extern void* VG_(ppc64_linux_REDIR_FOR_strchr)( void*, Int );
 /* A label (sans dot) marking the ultra-magical return stub via which
    all redirected and wrapped functions are made to "return" on
-- 
2.47.3