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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/kernel/entry-header.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/kernel/entry-header.S')
| -rw-r--r-- | arch/arm/kernel/entry-header.S | 3 |
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 |