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author | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-08-20 09:32:02 (GMT) |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2015-08-26 19:27:02 (GMT) |
commit | 2190fed67ba6f3e8129513929f2395843645e928 (patch) | |
tree | 45a4db5061c12e2926f7a1c89d56c7bbf47f0e61 /arch/arm/include | |
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/include')
-rw-r--r-- | arch/arm/include/asm/assembler.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/arm/include/asm/assembler.h b/arch/arm/include/asm/assembler.h index 4abe572..a911770 100644 --- a/arch/arm/include/asm/assembler.h +++ b/arch/arm/include/asm/assembler.h @@ -445,6 +445,23 @@ THUMB( orr \reg , \reg , #PSR_T_BIT ) #endif .endm + .macro uaccess_disable, tmp, isb=1 + .endm + + .macro uaccess_enable, tmp, isb=1 + .endm + + .macro uaccess_save, tmp + .endm + + .macro uaccess_restore + .endm + + .macro uaccess_save_and_disable, tmp + uaccess_save \tmp + uaccess_disable \tmp + .endm + .irp c,,eq,ne,cs,cc,mi,pl,vs,vc,hi,ls,ge,lt,gt,le,hs,lo .macro ret\c, reg #if __LINUX_ARM_ARCH__ < 6 |