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>
47 lines
1 KiB
ArmAsm
47 lines
1 KiB
ArmAsm
#include <linux/linkage.h>
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#include <asm/assembler.h>
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/*
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* Function: v7_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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*/
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.align 5
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ENTRY(v7_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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uaccess_disable ip @ disable userspace access
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/*
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* V6 code adjusts the returned DFSR.
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* New designs should not need to patch up faults.
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*/
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#if defined(CONFIG_VERIFY_PERMISSION_FAULT)
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/*
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* Detect erroneous permission failures and fix
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*/
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ldr r3, =0x40d @ On permission fault
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and r3, r1, r3
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cmp r3, #0x0d
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bne do_DataAbort
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mcr p15, 0, r0, c7, c8, 0 @ Retranslate FAR
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isb
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mrc p15, 0, ip, c7, c4, 0 @ Read the PAR
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and r3, ip, #0x7b @ On translation fault
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cmp r3, #0x0b
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bne do_DataAbort
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bic r1, r1, #0xf @ Fix up FSR FS[5:0]
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and ip, ip, #0x7e
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orr r1, r1, ip, LSR #1
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#endif
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b do_DataAbort
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ENDPROC(v7_early_abort)
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