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authorJames Morse <james.morse@arm.com>2016-02-05 14:58:48 +0000
committerCatalin Marinas <catalin.marinas@arm.com>2016-02-18 17:27:04 +0000
commit57f4959bad0a154aeca125b7d38d1d9471a12422 (patch)
tree6d75f86840bb0bd2d3f4928993f696c44e2033c0 /arch/arm64/lib/clear_user.S
parentarm64: add ARMv8.2 id_aa64mmfr2 boiler plate (diff)
downloadlinux-dev-57f4959bad0a154aeca125b7d38d1d9471a12422.tar.xz
linux-dev-57f4959bad0a154aeca125b7d38d1d9471a12422.zip
arm64: kernel: Add support for User Access Override
'User Access Override' is a new ARMv8.2 feature which allows the unprivileged load and store instructions to be overridden to behave in the normal way. This patch converts {get,put}_user() and friends to use ldtr*/sttr* instructions - so that they can only access EL0 memory, then enables UAO when fs==KERNEL_DS so that these functions can access kernel memory. This allows user space's read/write permissions to be checked against the page tables, instead of testing addr<USER_DS, then using the kernel's read/write permissions. Signed-off-by: James Morse <james.morse@arm.com> [catalin.marinas@arm.com: move uao_thread_switch() above dsb()] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to '')
-rw-r--r--arch/arm64/lib/clear_user.S8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/lib/clear_user.S b/arch/arm64/lib/clear_user.S
index a9723c71c52b..3f950b677c07 100644
--- a/arch/arm64/lib/clear_user.S
+++ b/arch/arm64/lib/clear_user.S
@@ -39,20 +39,20 @@ ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(0)), ARM64_HAS_PAN, \
subs x1, x1, #8
b.mi 2f
1:
-USER(9f, str xzr, [x0], #8 )
+uao_user_alternative 9f, str, sttr, xzr, x0, 8
subs x1, x1, #8
b.pl 1b
2: adds x1, x1, #4
b.mi 3f
-USER(9f, str wzr, [x0], #4 )
+uao_user_alternative 9f, str, sttr, wzr, x0, 4
sub x1, x1, #4
3: adds x1, x1, #2
b.mi 4f
-USER(9f, strh wzr, [x0], #2 )
+uao_user_alternative 9f, strh, sttrh, wzr, x0, 2
sub x1, x1, #2
4: adds x1, x1, #1
b.mi 5f
-USER(9f, strb wzr, [x0] )
+uao_user_alternative 9f, strb, sttrb, wzr, x0, 0
5: mov x0, #0
ALTERNATIVE("nop", __stringify(SET_PSTATE_PAN(1)), ARM64_HAS_PAN, \
CONFIG_ARM64_PAN)