diff options
| author | Jonathan Austin <Jonathan.Austin@arm.com> | 2012-04-12 17:45:25 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2012-04-15 22:00:31 +0100 |
| commit | 078c04545ba56da21567728a909a496df5ff730d (patch) | |
| tree | 08d0f061a972f426ef7d7c2ae227ac998ffca013 /arch | |
| parent | e5ab85800820edd907d3f43f285e1232f84d5a41 (diff) | |
ARM: 7384/1: ThumbEE: Disable userspace TEEHBR access for !CONFIG_ARM_THUMBEE
Currently when ThumbEE is not enabled (!CONFIG_ARM_THUMBEE) the ThumbEE
register states are not saved/restored at context switch. The default state
of the ThumbEE Ctrl register (TEECR) allows userspace accesses to the
ThumbEE Base Handler register (TEEHBR). This can cause unexpected behaviour
when people use ThumbEE on !CONFIG_ARM_THUMBEE kernels, as well as allowing
covert communication - eg between userspace tasks running inside chroot
jails.
This patch sets up TEECR in order to prevent user-space access to TEEHBR
when !CONFIG_ARM_THUMBEE. In this case, tasks are sent SIGILL if they try to
access TEEHBR.
Cc: stable@vger.kernel.org
Reviewed-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Jonathan Austin <jonathan.austin@arm.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/mm/proc-v7.S | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S index f1c8486f7501..c2e2b66f72b5 100644 --- a/arch/arm/mm/proc-v7.S +++ b/arch/arm/mm/proc-v7.S @@ -255,6 +255,18 @@ __v7_setup: mcr p15, 0, r5, c10, c2, 0 @ write PRRR mcr p15, 0, r6, c10, c2, 1 @ write NMRR #endif +#ifndef CONFIG_ARM_THUMBEE + mrc p15, 0, r0, c0, c1, 0 @ read ID_PFR0 for ThumbEE + and r0, r0, #(0xf << 12) @ ThumbEE enabled field + teq r0, #(1 << 12) @ check if ThumbEE is present + bne 1f + mov r5, #0 + mcr p14, 6, r5, c1, c0, 0 @ Initialize TEEHBR to 0 + mrc p14, 6, r0, c0, c0, 0 @ load TEECR + orr r0, r0, #1 @ set the 1st bit in order to + mcr p14, 6, r0, c0, c0, 0 @ stop userspace TEEHBR access +1: +#endif adr r5, v7_crval ldmia r5, {r5, r6} #ifdef CONFIG_CPU_ENDIAN_BE8 |