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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/kernel/armv8_deprecated.c
parent9ded63aaf83eba76e1a54ac02581c2badc497f1a (diff)
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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 'arch/arm64/kernel/armv8_deprecated.c')
-rw-r--r--arch/arm64/kernel/armv8_deprecated.c8
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/arm64/kernel/armv8_deprecated.c b/arch/arm64/kernel/armv8_deprecated.c
index 78d56bff91fd..bcee7abac68e 100644
--- a/arch/arm64/kernel/armv8_deprecated.c
+++ b/arch/arm64/kernel/armv8_deprecated.c
@@ -14,6 +14,8 @@
#include <linux/slab.h>
#include <linux/sysctl.h>
+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
#include <asm/insn.h>
#include <asm/opcodes.h>
#include <asm/sysreg.h>
@@ -280,6 +282,8 @@ static void register_insn_emulation_sysctl(struct ctl_table *table)
*/
#define __user_swpX_asm(data, addr, res, temp, B) \
__asm__ __volatile__( \
+ ALTERNATIVE("nop", SET_PSTATE_PAN(0), ARM64_HAS_PAN, \
+ CONFIG_ARM64_PAN) \
" mov %w2, %w1\n" \
"0: ldxr"B" %w1, [%3]\n" \
"1: stxr"B" %w0, %w2, [%3]\n" \
@@ -295,7 +299,9 @@ static void register_insn_emulation_sysctl(struct ctl_table *table)
" .align 3\n" \
" .quad 0b, 3b\n" \
" .quad 1b, 3b\n" \
- " .popsection" \
+ " .popsection\n" \
+ ALTERNATIVE("nop", SET_PSTATE_PAN(1), ARM64_HAS_PAN, \
+ CONFIG_ARM64_PAN) \
: "=&r" (res), "+r" (data), "=&r" (temp) \
: "r" (addr), "i" (-EAGAIN), "i" (-EFAULT) \
: "memory")