From d19f5e41b344a057bb2450024a807476f30978d2 Mon Sep 17 00:00:00 2001 From: Helge Deller Date: Sat, 25 Mar 2017 11:59:15 +0100 Subject: 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 Cc: # v4.9+ Signed-off-by: Helge Deller --- arch/parisc/lib/fixup.S | 98 ------------------------------------------------- 1 file changed, 98 deletions(-) delete mode 100644 arch/parisc/lib/fixup.S (limited to 'arch/parisc/lib/fixup.S') 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 - * - * 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 -#include -#include -#include - -#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) - -- cgit v1.2.3-59-g8ed1b