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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>
44 lines
1.2 KiB
ArmAsm
44 lines
1.2 KiB
ArmAsm
#include <linux/linkage.h>
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#include <asm/assembler.h>
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#include "abort-macro.S"
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/*
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* Function: v6_early_abort
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*
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* Params : r2 = pt_regs
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* : r4 = aborted context pc
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* : r5 = aborted context psr
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*
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* Returns : r4 - r11, r13 preserved
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*
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* Purpose : obtain information about current aborted instruction.
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* Note: we read user space. This means we might cause a data
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* abort here if the I-TLB and D-TLB aren't seeing the same
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* picture. Unfortunately, this does happen. We live with it.
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*/
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.align 5
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ENTRY(v6_early_abort)
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mrc p15, 0, r1, c5, c0, 0 @ get FSR
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mrc p15, 0, r0, c6, c0, 0 @ get FAR
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/*
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* Faulty SWP instruction on 1136 doesn't set bit 11 in DFSR.
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*/
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#ifdef CONFIG_ARM_ERRATA_326103
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ldr ip, =0x4107b36
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mrc p15, 0, r3, c0, c0, 0 @ get processor id
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teq ip, r3, lsr #4 @ r0 ARM1136?
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bne 1f
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tst r5, #PSR_J_BIT @ Java?
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tsteq r5, #PSR_T_BIT @ Thumb?
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bne 1f
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bic r1, r1, #1 << 11 @ clear bit 11 of FSR
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ldr r3, [r4] @ read aborted ARM instruction
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ARM_BE8(rev r3, r3)
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teq_ldrd tmp=ip, insn=r3 @ insn was LDRD?
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beq 1f @ yes
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tst r3, #1 << 20 @ L = 0 -> write
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orreq r1, r1, #1 << 11 @ yes.
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#endif
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1: uaccess_disable ip @ disable userspace access
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b do_DataAbort
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