ARM: entry: provide uaccess assembly macro hooks
authorRussell King <rmk+kernel@arm.linux.org.uk>
Thu, 20 Aug 2015 09:32:02 +0000 (10:32 +0100)
committerRussell King <rmk+kernel@arm.linux.org.uk>
Wed, 26 Aug 2015 19:27:02 +0000 (20:27 +0100)
commit2190fed67ba6f3e8129513929f2395843645e928
tree45a4db5061c12e2926f7a1c89d56c7bbf47f0e61
parentaa06e5c1f9c2b466712be904cc5b56a813e24cfd
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>
arch/arm/include/asm/assembler.h
arch/arm/kernel/entry-armv.S
arch/arm/kernel/entry-common.S
arch/arm/kernel/entry-header.S
arch/arm/mm/abort-ev4.S
arch/arm/mm/abort-ev5t.S
arch/arm/mm/abort-ev5tj.S
arch/arm/mm/abort-ev6.S
arch/arm/mm/abort-ev7.S
arch/arm/mm/abort-lv4t.S
arch/arm/mm/abort-macro.S