mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-11-17 09:14:19 +08:00
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>
This commit is contained in:
Helge Deller
parent
554bfeceb8
commit
d19f5e41b3
@ -64,6 +64,15 @@ struct exception_table_entry {
|
||||
".word (" #fault_addr " - .), (" #except_addr " - .)\n\t" \
|
||||
".previous\n"
|
||||
|
||||
/*
|
||||
* ASM_EXCEPTIONTABLE_ENTRY_EFAULT() creates a special exception table entry
|
||||
* (with lowest bit set) for which the fault handler in fixup_exception() will
|
||||
* load -EFAULT into %r8 for a read or write fault, and zeroes the target
|
||||
* register in case of a read fault in get_user().
|
||||
*/
|
||||
#define ASM_EXCEPTIONTABLE_ENTRY_EFAULT( fault_addr, except_addr )\
|
||||
ASM_EXCEPTIONTABLE_ENTRY( fault_addr, except_addr + 1)
|
||||
|
||||
/*
|
||||
* The page fault handler stores, in a per-cpu area, the following information
|
||||
* if a fixup routine is available.
|
||||
@ -91,7 +100,7 @@ struct exception_data {
|
||||
#define __get_user(x, ptr) \
|
||||
({ \
|
||||
register long __gu_err __asm__ ("r8") = 0; \
|
||||
register long __gu_val __asm__ ("r9") = 0; \
|
||||
register long __gu_val; \
|
||||
\
|
||||
load_sr2(); \
|
||||
switch (sizeof(*(ptr))) { \
|
||||
@ -107,22 +116,23 @@ struct exception_data {
|
||||
})
|
||||
|
||||
#define __get_user_asm(ldx, ptr) \
|
||||
__asm__("\n1:\t" ldx "\t0(%%sr2,%2),%0\n\t" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_get_user_skip_1)\
|
||||
__asm__("1: " ldx " 0(%%sr2,%2),%0\n" \
|
||||
"9:\n" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
|
||||
: "=r"(__gu_val), "=r"(__gu_err) \
|
||||
: "r"(ptr), "1"(__gu_err) \
|
||||
: "r1");
|
||||
: "r"(ptr), "1"(__gu_err));
|
||||
|
||||
#if !defined(CONFIG_64BIT)
|
||||
|
||||
#define __get_user_asm64(ptr) \
|
||||
__asm__("\n1:\tldw 0(%%sr2,%2),%0" \
|
||||
"\n2:\tldw 4(%%sr2,%2),%R0\n\t" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_get_user_skip_2)\
|
||||
ASM_EXCEPTIONTABLE_ENTRY(2b, fixup_get_user_skip_1)\
|
||||
__asm__(" copy %%r0,%R0\n" \
|
||||
"1: ldw 0(%%sr2,%2),%0\n" \
|
||||
"2: ldw 4(%%sr2,%2),%R0\n" \
|
||||
"9:\n" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
|
||||
: "=r"(__gu_val), "=r"(__gu_err) \
|
||||
: "r"(ptr), "1"(__gu_err) \
|
||||
: "r1");
|
||||
: "r"(ptr), "1"(__gu_err));
|
||||
|
||||
#endif /* !defined(CONFIG_64BIT) */
|
||||
|
||||
@ -148,32 +158,31 @@ struct exception_data {
|
||||
* The "__put_user/kernel_asm()" macros tell gcc they read from memory
|
||||
* instead of writing. This is because they do not write to any memory
|
||||
* gcc knows about, so there are no aliasing issues. These macros must
|
||||
* also be aware that "fixup_put_user_skip_[12]" are executed in the
|
||||
* context of the fault, and any registers used there must be listed
|
||||
* as clobbers. In this case only "r1" is used by the current routines.
|
||||
* r8/r9 are already listed as err/val.
|
||||
* also be aware that fixups are executed in the context of the fault,
|
||||
* and any registers used there must be listed as clobbers.
|
||||
* r8 is already listed as err.
|
||||
*/
|
||||
|
||||
#define __put_user_asm(stx, x, ptr) \
|
||||
__asm__ __volatile__ ( \
|
||||
"\n1:\t" stx "\t%2,0(%%sr2,%1)\n\t" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_1)\
|
||||
"1: " stx " %2,0(%%sr2,%1)\n" \
|
||||
"9:\n" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
|
||||
: "=r"(__pu_err) \
|
||||
: "r"(ptr), "r"(x), "0"(__pu_err) \
|
||||
: "r1")
|
||||
: "r"(ptr), "r"(x), "0"(__pu_err))
|
||||
|
||||
|
||||
#if !defined(CONFIG_64BIT)
|
||||
|
||||
#define __put_user_asm64(__val, ptr) do { \
|
||||
__asm__ __volatile__ ( \
|
||||
"\n1:\tstw %2,0(%%sr2,%1)" \
|
||||
"\n2:\tstw %R2,4(%%sr2,%1)\n\t" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY(1b, fixup_put_user_skip_2)\
|
||||
ASM_EXCEPTIONTABLE_ENTRY(2b, fixup_put_user_skip_1)\
|
||||
"1: stw %2,0(%%sr2,%1)\n" \
|
||||
"2: stw %R2,4(%%sr2,%1)\n" \
|
||||
"9:\n" \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(1b, 9b) \
|
||||
ASM_EXCEPTIONTABLE_ENTRY_EFAULT(2b, 9b) \
|
||||
: "=r"(__pu_err) \
|
||||
: "r"(ptr), "r"(__val), "0"(__pu_err) \
|
||||
: "r1"); \
|
||||
: "r"(ptr), "r"(__val), "0"(__pu_err)); \
|
||||
} while (0)
|
||||
|
||||
#endif /* !defined(CONFIG_64BIT) */
|
||||
|
||||
@ -47,16 +47,6 @@ EXPORT_SYMBOL(__cmpxchg_u64);
|
||||
EXPORT_SYMBOL(lclear_user);
|
||||
EXPORT_SYMBOL(lstrnlen_user);
|
||||
|
||||
/* Global fixups - defined as int to avoid creation of function pointers */
|
||||
extern int fixup_get_user_skip_1;
|
||||
extern int fixup_get_user_skip_2;
|
||||
extern int fixup_put_user_skip_1;
|
||||
extern int fixup_put_user_skip_2;
|
||||
EXPORT_SYMBOL(fixup_get_user_skip_1);
|
||||
EXPORT_SYMBOL(fixup_get_user_skip_2);
|
||||
EXPORT_SYMBOL(fixup_put_user_skip_1);
|
||||
EXPORT_SYMBOL(fixup_put_user_skip_2);
|
||||
|
||||
#ifndef CONFIG_64BIT
|
||||
/* Needed so insmod can set dp value */
|
||||
extern int $global$;
|
||||
|
||||
@ -2,7 +2,7 @@
|
||||
# Makefile for parisc-specific library files
|
||||
#
|
||||
|
||||
lib-y := lusercopy.o bitops.o checksum.o io.o memset.o fixup.o memcpy.o \
|
||||
lib-y := lusercopy.o bitops.o checksum.o io.o memset.o memcpy.o \
|
||||
ucmpdi2.o delay.o
|
||||
|
||||
obj-y := iomap.o
|
||||
|
||||
@ -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)
|
||||
|
||||
@ -150,6 +150,23 @@ int fixup_exception(struct pt_regs *regs)
|
||||
d->fault_space = regs->isr;
|
||||
d->fault_addr = regs->ior;
|
||||
|
||||
/*
|
||||
* Fix up get_user() and put_user().
|
||||
* ASM_EXCEPTIONTABLE_ENTRY_EFAULT() sets the least-significant
|
||||
* bit in the relative address of the fixup routine to indicate
|
||||
* that %r8 should be loaded with -EFAULT to report a userspace
|
||||
* access error.
|
||||
*/
|
||||
if (fix->fixup & 1) {
|
||||
regs->gr[8] = -EFAULT;
|
||||
|
||||
/* zero target register for get_user() */
|
||||
if (parisc_acctyp(0, regs->iir) == VM_READ) {
|
||||
int treg = regs->iir & 0x1f;
|
||||
regs->gr[treg] = 0;
|
||||
}
|
||||
}
|
||||
|
||||
regs->iaoq[0] = (unsigned long)&fix->fixup + fix->fixup;
|
||||
regs->iaoq[0] &= ~3;
|
||||
/*
|
||||
|
||||
Loading…
Reference in New Issue
Block a user