linux/arch/arm/mm/abort-ev7.S
Russell King 2190fed67b ARM: entry: provide uaccess assembly macro hooks
Provide hooks into the kernel entry and exit paths to permit control
of userspace visibility to the kernel.  The intended use is:

- on entry to kernel from user, uaccess_disable will be called to
  disable userspace visibility
- on exit from kernel to user, uaccess_enable will be called to
  enable userspace visibility
- on entry from a kernel exception, uaccess_save_and_disable will be
  called to save the current userspace visibility setting, and disable
  access
- on exit from a kernel exception, uaccess_restore will be called to
  restore the userspace visibility as it was before the exception
  occurred.

These hooks allows us to keep userspace visibility disabled for the
vast majority of the kernel, except for localised regions where we
want to explicitly access userspace.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2015-08-26 20:27:02 +01:00

47 lines
1.0 KiB
ArmAsm

#include <linux/linkage.h>
#include <asm/assembler.h>
/*
* Function: v7_early_abort
*
* Params : r2 = pt_regs
* : r4 = aborted context pc
* : r5 = aborted context psr
*
* Returns : r4 - r11, r13 preserved
*
* Purpose : obtain information about current aborted instruction.
*/
.align 5
ENTRY(v7_early_abort)
mrc p15, 0, r1, c5, c0, 0 @ get FSR
mrc p15, 0, r0, c6, c0, 0 @ get FAR
uaccess_disable ip @ disable userspace access
/*
* V6 code adjusts the returned DFSR.
* New designs should not need to patch up faults.
*/
#if defined(CONFIG_VERIFY_PERMISSION_FAULT)
/*
* Detect erroneous permission failures and fix
*/
ldr r3, =0x40d @ On permission fault
and r3, r1, r3
cmp r3, #0x0d
bne do_DataAbort
mcr p15, 0, r0, c7, c8, 0 @ Retranslate FAR
isb
mrc p15, 0, ip, c7, c4, 0 @ Read the PAR
and r3, ip, #0x7b @ On translation fault
cmp r3, #0x0b
bne do_DataAbort
bic r1, r1, #0xf @ Fix up FSR FS[5:0]
and ip, ip, #0x7e
orr r1, r1, ip, LSR #1
#endif
b do_DataAbort
ENDPROC(v7_early_abort)