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| author | James Morse <james.morse@arm.com> | 2015-07-22 20:05:54 +0200 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-07-27 12:08:41 +0200 |
| commit | 338d4f49d6f7114a017d294ccf7374df4f998edc (patch) | |
| tree | af0b5cedc6e042623346d4e82be24eda190626a1 /arch/arm64/kernel/armv8_deprecated.c | |
| parent | arm64: Generalise msr_s/mrs_s operations (diff) | |
| download | linux-338d4f49d6f7114a017d294ccf7374df4f998edc.tar.xz linux-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 'arch/arm64/kernel/armv8_deprecated.c')
| -rw-r--r-- | arch/arm64/kernel/armv8_deprecated.c | 8 |
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") |