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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/kernel/entry-header.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/kernel/entry-header.S')
-rw-r--r--arch/arm/kernel/entry-header.S3
1 files changed, 3 insertions, 0 deletions
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index d47b5161b029..0d22ad206d52 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -215,6 +215,7 @@
blne trace_hardirqs_off
#endif
.endif
+ uaccess_restore
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode SVC restore
@@ -258,6 +259,7 @@
@ on the stack remains correct).
@
.macro svc_exit_via_fiq
+ uaccess_restore
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode restore
mov r0, sp
@@ -287,6 +289,7 @@
.macro restore_user_regs, fast = 0, offset = 0
+ uaccess_enable r1, isb=0
#ifndef CONFIG_THUMB2_KERNEL
@ ARM mode restore
mov r2, sp