From 071a51cf9750489e15390d62579236acd2dcf87e Mon Sep 17 00:00:00 2001
From: Nathan Whitehorn <nwhitehorn@FreeBSD.org>
Date: Tue, 28 Dec 2010 22:31:59 +0000
Subject: [PATCH] Fix an error in the ABI in rtld_bind_start(). When passing
 arguments to a C function, the caller's stack frame must have room to store
 all of the arguments to that function. While here, fix stack frame alignment
 issues.

Without this change, the compiler will save r3 and r4 into the caller's
stack frame before calling setjmp() in _rtld_bind(). These would then
overwrite arguments to the newly-bound function, causing eventual failures.
---
 libexec/rtld-elf/powerpc64/rtld_start.S | 84 ++++++++++++-------------
 1 file changed, 42 insertions(+), 42 deletions(-)

diff --git a/libexec/rtld-elf/powerpc64/rtld_start.S b/libexec/rtld-elf/powerpc64/rtld_start.S
index c44f880f6c83..3c962c20ed35 100644
--- a/libexec/rtld-elf/powerpc64/rtld_start.S
+++ b/libexec/rtld-elf/powerpc64/rtld_start.S
@@ -35,15 +35,15 @@
 .extern _DYNAMIC
 
 _ENTRY(_rtld_start)
-	stdu    %r1,-96(%r1)	/* 16-byte aligned stack for reg saves +
+	stdu    %r1,-144(%r1)	/* 16-byte aligned stack for reg saves +
 				exit_proc & obj _rtld args +
 				backchain & lrsave stack frame */
-	std     %r3,48(%r1)	/*  argc */
-	std     %r4,56(%r1)	/*  argv */
-	std     %r5,64(%r1)	/*  envp */
-/*	std     %r6,72(%r1)   *//*  obj (always 0) */
-/*	std     %r7,80(%r1)   *//*  cleanup (always 0) */
-	std     %r8,88(%r1)	/*  ps_strings */
+	std     %r3,96(%r1)	/*  argc */
+	std     %r4,104(%r1)	/*  argv */
+	std     %r5,112(%r1)	/*  envp */
+/*	std     %r6,120(%r1)   *//*  obj (always 0) */
+/*	std     %r7,128(%r1)   *//*  cleanup (always 0) */
+	std     %r8,136(%r1)	/*  ps_strings */
 
 	/*
 	 * Perform initial relocation of ld-elf.so. Not as easy as it
@@ -75,10 +75,10 @@ _ENTRY(_rtld_start)
 	 * original stack layout has to be found by moving back a word
 	 * from the argv pointer.
 	 */
-	ld	%r4,56(%r1)
+	ld	%r4,104(%r1)
         addi    %r3,%r4,-8	/* locate argc ptr, &argv[-1] */
-	addi	%r4,%r1,80	/* &exit_proc on stack */
-	addi	%r5,%r1,72	/* &obj_main on stack */
+	addi	%r4,%r1,128	/* &exit_proc on stack */
+	addi	%r5,%r1,120	/* &obj_main on stack */
 
 	bl      ._rtld		/* &_start = _rtld(sp, &exit_proc, &obj_main)*/
 	nop
@@ -90,12 +90,12 @@ _ENTRY(_rtld_start)
 	/*
 	 * Restore args, with new obj/exit proc
 	 */
-	ld      %r3,48(%r1)     /* argc */
-	ld      %r4,56(%r1)	/* argv */
-	ld      %r5,64(%r1)	/* envp */
-	ld      %r6,72(%r1)	/* obj */
-	ld      %r7,80(%r1)	/* exit proc */
-	ld      %r8,88(%r1)	/* ps_strings */
+	ld      %r3,96(%r1)     /* argc */
+	ld      %r4,104(%r1)	/* argv */
+	ld      %r5,112(%r1)	/* envp */
+	ld      %r6,120(%r1)	/* obj */
+	ld      %r7,128(%r1)	/* exit proc */
+	ld      %r8,136(%r1)	/* ps_strings */
 
 	blrl	/* _start(argc, argv, envp, obj, cleanup, ps_strings) */
 
@@ -119,16 +119,17 @@ _ENTRY(_rtld_bind_start)
 	mfcr    %r0
 	std     %r0,8(%r1)		# save cr
 
-	stdu    %r1,-48-9*8(%r1)	# stack space for 8 regs + header
-	std	%r3,48+0*8(%r1)		# save r3-r31
-	std	%r4,48+1*8(%r1)
-	std	%r5,48+2*8(%r1)
-	std	%r6,48+3*8(%r1)
-	std	%r7,48+4*8(%r1)
-	std	%r8,48+5*8(%r1)
-	std	%r9,48+6*8(%r1)
-	std	%r10,48+7*8(%r1)
-	std	%r12,48+8*8(%r1)
+	stdu    %r1,-48-12*8(%r1)	# stack space for 8 regs + header
+					#   + 2 save regs
+	std	%r3,64+0*8(%r1)		# save r3-r31
+	std	%r4,64+1*8(%r1)
+	std	%r5,64+2*8(%r1)
+	std	%r6,64+3*8(%r1)
+	std	%r7,64+4*8(%r1)
+	std	%r8,64+5*8(%r1)
+	std	%r9,64+6*8(%r1)
+	std	%r10,64+7*8(%r1)
+	std	%r12,64+8*8(%r1)
 
 	ld	%r3,0(%r11)
 	ld	%r4,8(%r11)
@@ -140,22 +141,21 @@ _ENTRY(_rtld_bind_start)
 	ld	%r3,0(%r3)
 	mtctr   %r3			# move absolute target addr into ctr
 
-        ld	%r3,48+0*8(%r1)		# restore r3-r31
-        ld	%r4,48+1*8(%r1)
-        ld	%r5,48+2*8(%r1)
-        ld	%r6,48+3*8(%r1)
-	ld	%r7,48+4*8(%r1)
-	ld	%r8,48+5*8(%r1)
-	ld	%r9,48+6*8(%r1)
-	ld	%r10,48+7*8(%r1)
-	ld	%r12,48+8*8(%r1)
+	ld	%r3,64+0*8(%r1)		# restore r3-r31
+	ld	%r4,64+1*8(%r1)
+	ld	%r5,64+2*8(%r1)
+	ld	%r6,64+3*8(%r1)
+	ld	%r7,64+4*8(%r1)
+	ld	%r8,64+5*8(%r1)
+	ld	%r9,64+6*8(%r1)
+	ld	%r10,64+7*8(%r1)
+	ld	%r12,64+8*8(%r1)
 
-        addi    %r1,%r1,48+9*8		# restore stack
+	ld	%r1,0(%r1)		# restore stack
+	ld	%r0,8(%r1)		# restore cr
+	mtcr    %r0
+	ld	%r0,16(%r1)		# restore lr
+	mtlr    %r0
 
-        ld	%r0,8(%r1)		# restore cr
-        mtcr    %r0
-        ld	%r0,16(%r1)		# restore lr
-        mtlr    %r0
-
-        bctr				# jump to target
+	bctr				# jump to target