2190fed67b
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>
27 lines
832 B
ArmAsm
27 lines
832 B
ArmAsm
#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* Function: v4_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(v4_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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ldr r3, [r4] @ read aborted ARM instruction
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uaccess_disable ip @ disable userspace access
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bic r1, r1, #1 << 11 | 1 << 10 @ clear bits 11 and 10 of FSR
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tst r3, #1 << 20 @ L = 1 -> write?
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orreq r1, r1, #1 << 11 @ yes.
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b do_DataAbort
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