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authorHelge Deller <deller@gmx.de>2017-03-25 11:59:15 +0100
committerHelge Deller <deller@gmx.de>2017-03-29 21:50:36 +0200
commitd19f5e41b344a057bb2450024a807476f30978d2 (patch)
tree4f7f4fa52e5e845ec0abe38d1906404d575ca8ab /arch/parisc/lib/fixup.S
parentparisc: Fix access fault handling in pa_memcpy() (diff)
downloadlinux-dev-d19f5e41b344a057bb2450024a807476f30978d2.tar.xz
linux-dev-d19f5e41b344a057bb2450024a807476f30978d2.zip
parisc: Clean up fixup routines for get_user()/put_user()
Al Viro noticed that userspace accesses via get_user()/put_user() can be simplified a lot with regard to usage of the exception handling. This patch implements a fixup routine for get_user() and put_user() in such that the exception handler will automatically load -EFAULT into the register %r8 (the error value) in case on a fault on userspace. Additionally the fixup routine will zero the target register on fault in case of a get_user() call. The target register is extracted out of the faulting assembly instruction. This patch brings a few benefits over the old implementation: 1. Exception handling gets much cleaner, easier and smaller in size. 2. Helper functions like fixup_get_user_skip_1 (all of fixup.S) can be dropped. 3. No need to hardcode %r9 as target register for get_user() any longer. This helps the compiler register allocator and thus creates less assembler statements. 4. No dependency on the exception_data contents any longer. 5. Nested faults will be handled cleanly. Reported-by: Al Viro <viro@ZenIV.linux.org.uk> Cc: <stable@vger.kernel.org> # v4.9+ Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to '')
-rw-r--r--arch/parisc/lib/fixup.S98
1 files changed, 0 insertions, 98 deletions
diff --git a/arch/parisc/lib/fixup.S b/arch/parisc/lib/fixup.S
deleted file mode 100644
index a5b72f22c7a6..000000000000
--- a/arch/parisc/lib/fixup.S
+++ /dev/null
@@ -1,98 +0,0 @@
-/*
- * Linux/PA-RISC Project (http://www.parisc-linux.org/)
- *
- * Copyright (C) 2004 Randolph Chung <tausq@debian.org>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
- *
- * Fixup routines for kernel exception handling.
- */
-#include <asm/asm-offsets.h>
-#include <asm/assembly.h>
-#include <asm/errno.h>
-#include <linux/linkage.h>
-
-#ifdef CONFIG_SMP
- .macro get_fault_ip t1 t2
- loadgp
- addil LT%__per_cpu_offset,%r27
- LDREG RT%__per_cpu_offset(%r1),\t1
- /* t2 = smp_processor_id() */
- mfctl 30,\t2
- ldw TI_CPU(\t2),\t2
-#ifdef CONFIG_64BIT
- extrd,u \t2,63,32,\t2
-#endif
- /* t2 = &__per_cpu_offset[smp_processor_id()]; */
- LDREGX \t2(\t1),\t2
- addil LT%exception_data,%r27
- LDREG RT%exception_data(%r1),\t1
- /* t1 = this_cpu_ptr(&exception_data) */
- add,l \t1,\t2,\t1
- /* %r27 = t1->fault_gp - restore gp */
- LDREG EXCDATA_GP(\t1), %r27
- /* t1 = t1->fault_ip */
- LDREG EXCDATA_IP(\t1), \t1
- .endm
-#else
- .macro get_fault_ip t1 t2
- loadgp
- /* t1 = this_cpu_ptr(&exception_data) */
- addil LT%exception_data,%r27
- LDREG RT%exception_data(%r1),\t2
- /* %r27 = t2->fault_gp - restore gp */
- LDREG EXCDATA_GP(\t2), %r27
- /* t1 = t2->fault_ip */
- LDREG EXCDATA_IP(\t2), \t1
- .endm
-#endif
-
- .level LEVEL
-
- .text
- .section .fixup, "ax"
-
- /* get_user() fixups, store -EFAULT in r8, and 0 in r9 */
-ENTRY_CFI(fixup_get_user_skip_1)
- get_fault_ip %r1,%r8
- ldo 4(%r1), %r1
- ldi -EFAULT, %r8
- bv %r0(%r1)
- copy %r0, %r9
-ENDPROC_CFI(fixup_get_user_skip_1)
-
-ENTRY_CFI(fixup_get_user_skip_2)
- get_fault_ip %r1,%r8
- ldo 8(%r1), %r1
- ldi -EFAULT, %r8
- bv %r0(%r1)
- copy %r0, %r9
-ENDPROC_CFI(fixup_get_user_skip_2)
-
- /* put_user() fixups, store -EFAULT in r8 */
-ENTRY_CFI(fixup_put_user_skip_1)
- get_fault_ip %r1,%r8
- ldo 4(%r1), %r1
- bv %r0(%r1)
- ldi -EFAULT, %r8
-ENDPROC_CFI(fixup_put_user_skip_1)
-
-ENTRY_CFI(fixup_put_user_skip_2)
- get_fault_ip %r1,%r8
- ldo 8(%r1), %r1
- bv %r0(%r1)
- ldi -EFAULT, %r8
-ENDPROC_CFI(fixup_put_user_skip_2)
-