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authorJames Morse <james.morse@arm.com>2015-07-22 19:05:54 +0100
committerWill Deacon <will.deacon@arm.com>2015-07-27 11:08:41 +0100
commit338d4f49d6f7114a017d294ccf7374df4f998edc (patch)
treeaf0b5cedc6e042623346d4e82be24eda190626a1 /arch/arm64/include/asm/futex.h
parentarm64: Generalise msr_s/mrs_s operations (diff)
downloadlinux-dev-338d4f49d6f7114a017d294ccf7374df4f998edc.tar.xz
linux-dev-338d4f49d6f7114a017d294ccf7374df4f998edc.zip
arm64: kernel: Add support for Privileged Access Never
'Privileged Access Never' is a new arm8.1 feature which prevents privileged code from accessing any virtual address where read or write access is also permitted at EL0. This patch enables the PAN feature on all CPUs, and modifies {get,put}_user helpers temporarily to permit access. This will catch kernel bugs where user memory is accessed directly. 'Unprivileged loads and stores' using ldtrb et al are unaffected by PAN. Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: James Morse <james.morse@arm.com> [will: use ALTERNATIVE in asm and tidy up pan_enable check] Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to '')
-rw-r--r--arch/arm64/include/asm/futex.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/futex.h b/arch/arm64/include/asm/futex.h
index 74069b3bd919..775e85b9d1f2 100644
--- a/arch/arm64/include/asm/futex.h
+++ b/arch/arm64/include/asm/futex.h
@@ -20,10 +20,16 @@
#include <linux/futex.h>
#include <linux/uaccess.h>
+
+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
#include <asm/errno.h>
+#include <asm/sysreg.h>
#define __futex_atomic_op(insn, ret, oldval, uaddr, tmp, oparg) \
asm volatile( \
+ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \
+ CONFIG_ARM64_PAN) \
"1: ldxr %w1, %2\n" \
insn "\n" \
"2: stlxr %w3, %w0, %2\n" \
@@ -39,6 +45,8 @@
" .align 3\n" \
" .quad 1b, 4b, 2b, 4b\n" \
" .popsection\n" \
+ ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \
+ CONFIG_ARM64_PAN) \
: "=&r" (ret), "=&r" (oldval), "+Q" (*uaddr), "=&r" (tmp) \
: "r" (oparg), "Ir" (-EFAULT) \
: "memory")