From 2190fed67ba6f3e8129513929f2395843645e928 Mon Sep 17 00:00:00 2001 From: Russell King Date: Thu, 20 Aug 2015 10:32:02 +0100 Subject: 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 --- arch/arm/mm/abort-lv4t.S | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/arm/mm/abort-lv4t.S') diff --git a/arch/arm/mm/abort-lv4t.S b/arch/arm/mm/abort-lv4t.S index f3982580c273..6d8e8e3365d1 100644 --- a/arch/arm/mm/abort-lv4t.S +++ b/arch/arm/mm/abort-lv4t.S @@ -26,6 +26,7 @@ ENTRY(v4t_late_abort) #endif bne .data_thumb_abort ldr r8, [r4] @ read arm instruction + uaccess_disable ip @ disable userspace access tst r8, #1 << 20 @ L = 1 -> write? orreq r1, r1, #1 << 11 @ yes. and r7, r8, #15 << 24 @@ -155,6 +156,7 @@ ENTRY(v4t_late_abort) .data_thumb_abort: ldrh r8, [r4] @ read instruction + uaccess_disable ip @ disable userspace access tst r8, #1 << 11 @ L = 1 -> write? orreq r1, r1, #1 << 8 @ yes and r7, r8, #15 << 12 -- cgit v1.2.3-55-g7522