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authorRussell King <rmk+kernel@arm.linux.org.uk>2015-08-20 12:32:02 +0300
committerRussell King <rmk+kernel@arm.linux.org.uk>2015-08-26 22:27:02 +0300
commit2190fed67ba6f3e8129513929f2395843645e928 (patch)
tree45a4db5061c12e2926f7a1c89d56c7bbf47f0e61 /arch/arm/mm/abort-ev4.S
parentaa06e5c1f9c2b466712be904cc5b56a813e24cfd (diff)
downloadlinux-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.S1
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.