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| author | Christopher Covington <cov@codeaurora.org> | 2017-02-08 23:08:37 +0300 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2017-02-10 14:22:12 +0300 |
| commit | 38fd94b0275c91071157a03cc27676909b23dcde (patch) | |
| tree | bd035ae9cfee02889ec65bcc1f94aef66a8c6a08 /arch/arm64/mm | |
| parent | 2bf47e194608192b7346baea1d57929a87ced3f9 (diff) | |
| download | linux-38fd94b0275c91071157a03cc27676909b23dcde.tar.xz | |
arm64: Work around Falkor erratum 1003
The Qualcomm Datacenter Technologies Falkor v1 CPU may allocate TLB entries
using an incorrect ASID when TTBRx_EL1 is being updated. When the erratum
is triggered, page table entries using the new translation table base
address (BADDR) will be allocated into the TLB using the old ASID. All
circumstances leading to the incorrect ASID being cached in the TLB arise
when software writes TTBRx_EL1[ASID] and TTBRx_EL1[BADDR], a memory
operation is in the process of performing a translation using the specific
TTBRx_EL1 being written, and the memory operation uses a translation table
descriptor designated as non-global. EL2 and EL3 code changing the EL1&0
ASID is not subject to this erratum because hardware is prohibited from
performing translations from an out-of-context translation regime.
Consider the following pseudo code.
write new BADDR and ASID values to TTBRx_EL1
Replacing the above sequence with the one below will ensure that no TLB
entries with an incorrect ASID are used by software.
write reserved value to TTBRx_EL1[ASID]
ISB
write new value to TTBRx_EL1[BADDR]
ISB
write new value to TTBRx_EL1[ASID]
ISB
When the above sequence is used, page table entries using the new BADDR
value may still be incorrectly allocated into the TLB using the reserved
ASID. Yet this will not reduce functionality, since TLB entries incorrectly
tagged with the reserved ASID will never be hit by a later instruction.
Based on work by Shanker Donthineni <shankerd@codeaurora.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/mm')
| -rw-r--r-- | arch/arm64/mm/context.c | 11 | ||||
| -rw-r--r-- | arch/arm64/mm/proc.S | 1 |
2 files changed, 12 insertions, 0 deletions
diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index 4c63cb154859..68634c630cdd 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -79,6 +79,13 @@ void verify_cpu_asid_bits(void) } } +static void set_reserved_asid_bits(void) +{ + if (IS_ENABLED(CONFIG_QCOM_FALKOR_ERRATUM_1003) && + cpus_have_const_cap(ARM64_WORKAROUND_QCOM_FALKOR_E1003)) + __set_bit(FALKOR_RESERVED_ASID, asid_map); +} + static void flush_context(unsigned int cpu) { int i; @@ -87,6 +94,8 @@ static void flush_context(unsigned int cpu) /* Update the list of reserved ASIDs and the ASID bitmap. */ bitmap_clear(asid_map, 0, NUM_USER_ASIDS); + set_reserved_asid_bits(); + /* * Ensure the generation bump is observed before we xchg the * active_asids. @@ -244,6 +253,8 @@ static int asids_init(void) panic("Failed to allocate bitmap for %lu ASIDs\n", NUM_USER_ASIDS); + set_reserved_asid_bits(); + pr_info("ASID allocator initialised with %lu entries\n", NUM_USER_ASIDS); return 0; } diff --git a/arch/arm64/mm/proc.S b/arch/arm64/mm/proc.S index 32682be978e0..cd4d53d7e458 100644 --- a/arch/arm64/mm/proc.S +++ b/arch/arm64/mm/proc.S @@ -138,6 +138,7 @@ ENDPROC(cpu_do_resume) * - pgd_phys - physical address of new TTB */ ENTRY(cpu_do_switch_mm) + pre_ttbr0_update_workaround x0, x1, x2 mmid x1, x1 // get mm->context.id bfi x0, x1, #48, #16 // set the ASID msr ttbr0_el1, x0 // set TTBR0 |