From: miod <miod@openbsd.org>
Date: Mon, 1 Jun 2015 19:02:11 +0000 (+0000)
Subject: Since the __{div,rem}{l,q}{,u} special libc entry points use a specific
X-Git-Url: http://artulab.com/gitweb/?a=commitdiff_plain;h=ba4624ee143a0c6453f7aa6bfc68d9c16c7e984c;p=openbsd

Since the __{div,rem}{l,q}{,u} special libc entry points use a specific
calling convention which conflicts over t11 usage with the secureplt
calling convention, force these symbols to be `notype' rather `function', so
that the linker will not attempt to use plt relocations for them in the
absence of explicit relocation information.

Note that these symbols are still public and still callable with the old plt
convention, so existing binaries will still work with an updated libc, and
no libc version change is necessary.
---

diff --git a/lib/libc/arch/alpha/gen/divrem.m4 b/lib/libc/arch/alpha/gen/divrem.m4
index 94ec9201379..cb3501075ca 100644
--- a/lib/libc/arch/alpha/gen/divrem.m4
+++ b/lib/libc/arch/alpha/gen/divrem.m4
@@ -1,4 +1,4 @@
-/*	$OpenBSD: divrem.m4,v 1.4 2003/03/01 00:19:08 miod Exp $	*/
+/*	$OpenBSD: divrem.m4,v 1.5 2015/06/01 19:02:11 miod Exp $	*/
 /*	$NetBSD: divrem.m4,v 1.7 1996/10/17 03:08:04 cgd Exp $	*/
 
 /*
@@ -57,16 +57,41 @@ ifelse(S, `true', `define(NEG, `t4')')
 
 #include <machine/asm.h>
 
-LEAF(NAME, 0)					/* XXX */
+/*
+ * These functions use t11 as an input, which makes them incompatible with
+ * the secureplt calling sequence. The compiler knows about this, and will
+ * ask for a call through a got relocation. But this can only work if the
+ * linker omits creating a plt entry for the symbol. In order to achieve
+ * this, we need to declare it as `notype' instead of `function', which
+ * means that LEAF(NAME, 0) can't be used as it uses .ent which forces the
+ * `function' type.
+ */
+	.globl	NAME
+	.type	NAME, @notype
+	.usepv	NAME, no
+
+	.cfi_startproc
+	.cfi_return_column ra
+NAME:
+	MCOUNT
 	lda	sp, -64(sp)
+	.cfi_def_cfa_offset 64
 	stq	BIT, 0(sp)
+	.cfi_rel_offset BIT, 0
 	stq	I, 8(sp)
+	.cfi_rel_offset I, 8
 	stq	CC, 16(sp)
+	.cfi_rel_offset CC, 16
 	stq	T_0, 24(sp)
-ifelse(S, `true',
-`	stq	NEG, 32(sp)')
+	.cfi_rel_offset T_0, 24
+ifelse(S, `true',`dnl
+	stq	NEG, 32(sp)
+	.cfi_rel_offset NEG, 32
+')dnl
 	stq	A, 40(sp)
+	.cfi_rel_offset A, 40
 	stq	B, 48(sp)
+	.cfi_rel_offset B, 48
 	mov	zero, RESULT			/* Initialize result to zero */
 
 ifelse(S, `true',
@@ -177,14 +202,23 @@ ifelse(S, `true',
 ')
 
 	ldq	BIT, 0(sp)
+	.cfi_restore BIT
 	ldq	I, 8(sp)
+	.cfi_restore I
 	ldq	CC, 16(sp)
+	.cfi_restore CC
 	ldq	T_0, 24(sp)
-ifelse(S, `true',
-`	ldq	NEG, 32(sp)')
+	.cfi_restore T_0
+ifelse(S, `true',`dnl
+	ldq	NEG, 32(sp)
+	.cfi_restore NEG
+')dnl
 	ldq	A, 40(sp)
+	.cfi_restore A
 	ldq	B, 48(sp)
+	.cfi_restore B
 	lda	sp, 64(sp)
+	.cfi_def_cfa_offset 0
 	ret	zero, (t9), 1
 
 Ldotrap:
@@ -195,4 +229,9 @@ ifelse(OP, `div',
 ')
 	br	zero, Lret_result
 
-END(NAME)
+/*
+ * For the reasons stated above, we can not use END(NAME) either, as it
+ * expands to .end which requires a matching .ent.
+ */
+	.cfi_endproc
+	.size	NAME, . - NAME