From: Julian Seward <jseward@acm.org>
Date: Mon, 10 Sep 2007 16:52:09 +0000 (+0000)
Subject: ppc64-linux equivalent to r6813 (use sigframe return stub in
X-Git-Tag: svn/VALGRIND_3_3_0~219
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6e8fce154898a219a01a119ea18d85654d6ccfe3;p=thirdparty%2Fvalgrind.git

ppc64-linux equivalent to r6813 (use sigframe return stub in
m_trampoline, not on the stack)



git-svn-id: svn://svn.valgrind.org/valgrind/trunk@6814
---

diff --git a/coregrind/m_sigframe/sigframe-ppc64-linux.c b/coregrind/m_sigframe/sigframe-ppc64-linux.c
index 530df2a6d3..437b3e7c93 100644
--- a/coregrind/m_sigframe/sigframe-ppc64-linux.c
+++ b/coregrind/m_sigframe/sigframe-ppc64-linux.c
@@ -260,8 +260,16 @@ void VG_(sigframe_create)( ThreadId tid,
    /* XXX should do FP and vector regs */
 
    /* set up signal return trampoline */
-   frame->tramp[0] = 0x38000000U + __NR_rt_sigreturn; /* li 0,__NR_rt_sigreturn */
-   frame->tramp[1] = 0x44000002U;                     /* sc */
+   /* NB.  5 Sept 07.  mc->mc_pad[0..1] used to contain a the code to
+      which the signal handler returns, and it just did sys_sigreturn
+      or sys_rt_sigreturn.  But this doesn't work if the stack is
+      non-executable, and it isn't consistent with the x86-linux and
+      amd64-linux scheme for removing the stack frame.  So instead be
+      consistent and use a stub in m_trampoline.  Then it doesn't
+      matter whether or not the (guest) stack is executable.  This
+      fixes #149519 and #145837. */
+   frame->tramp[0] = 0; /* invalid */
+   frame->tramp[1] = 0; /* invalid */
    VG_TRACK(post_mem_write, Vg_CoreSignal, tst->tid,
             (Addr)&frame->tramp, sizeof(frame->tramp));
 
@@ -270,7 +278,7 @@ void VG_(sigframe_create)( ThreadId tid,
                               sizeof(frame->tramp), "stack_mcontext" );   
 
    /* set the signal handler to return to the trampoline */
-   SET_SIGNAL_LR(tst, (Addr) &frame->tramp[0]);
+   SET_SIGNAL_LR(tst, (Addr)&VG_(ppc64_linux_SUBST_FOR_rt_sigreturn));
 
    /* Stack pointer for the handler .. (note, back chain set
       earlier) */
diff --git a/coregrind/m_trampoline.S b/coregrind/m_trampoline.S
index 10d5ec4036..7b6f7a3abe 100644
--- a/coregrind/m_trampoline.S
+++ b/coregrind/m_trampoline.S
@@ -365,6 +365,12 @@ VG_(trampoline_stuff_end):
 .global VG_(trampoline_stuff_start)
 VG_(trampoline_stuff_start):
 
+.global VG_(ppc64_linux_SUBST_FOR_rt_sigreturn)
+VG_(ppc64_linux_SUBST_FOR_rt_sigreturn):
+	li 0,__NR_rt_sigreturn
+        sc
+        .long 0	/*illegal insn*/
+
 	/* See comment in pub_core_trampoline.h for what this is for */
 .global VG_(ppctoc_magic_redirect_return_stub)
 VG_(ppctoc_magic_redirect_return_stub):
diff --git a/coregrind/pub_core_trampoline.h b/coregrind/pub_core_trampoline.h
index da9ff416ec..6aac398bbf 100644
--- a/coregrind/pub_core_trampoline.h
+++ b/coregrind/pub_core_trampoline.h
@@ -77,6 +77,7 @@ extern void* VG_(ppc32_linux_REDIR_FOR_strchr)( void*, Int );
 #endif
 
 #if defined(VGP_ppc64_linux)
+extern void  VG_(ppc64_linux_SUBST_FOR_rt_sigreturn);
 extern UInt  VG_(ppc64_linux_REDIR_FOR_strlen)( void* );
 extern void* VG_(ppc64_linux_REDIR_FOR_strchr)( void*, Int );
 /* A label (sans dot) marking the ultra-magical return stub via which