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| author | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-08-20 12:32:02 +0300 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-08-26 22:27:02 +0300 |
| commit | 2190fed67ba6f3e8129513929f2395843645e928 (patch) | |
| tree | 45a4db5061c12e2926f7a1c89d56c7bbf47f0e61 /arch/arm/mm/abort-ev4.S | |
| parent | aa06e5c1f9c2b466712be904cc5b56a813e24cfd (diff) | |
| download | linux-2190fed67ba6f3e8129513929f2395843645e928.tar.xz | |
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>
Diffstat (limited to 'arch/arm/mm/abort-ev4.S')
| -rw-r--r-- | arch/arm/mm/abort-ev4.S | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/arm/mm/abort-ev4.S b/arch/arm/mm/abort-ev4.S index 54473cd4aba9..b3b31e30cadd 100644 --- a/arch/arm/mm/abort-ev4.S +++ b/arch/arm/mm/abort-ev4.S @@ -19,6 +19,7 @@ ENTRY(v4_early_abort) mrc p15, 0, r1, c5, c0, 0 @ get FSR mrc p15, 0, r0, c6, c0, 0 @ get FAR ldr r3, [r4] @ read aborted ARM instruction + uaccess_disable ip @ disable userspace access bic r1, r1, #1 << 11 | 1 << 10 @ clear bits 11 and 10 of FSR tst r3, #1 << 20 @ L = 1 -> write? orreq r1, r1, #1 << 11 @ yes. |