runtime_exceptions: Update AT speculative workaround
As per latest mailing communication [1], we decided to
update AT speculative workaround implementation in order to
disable page table walk for lower ELs(EL1 or EL0) immediately
after context switching to EL3 from lower ELs.
Previous implementation of AT speculative workaround is available
here: 45aecff00
AT speculative workaround is updated as below:
1. Avoid saving and restoring of SCTLR and TCR registers for EL1
in context save and restore routine respectively.
2. On EL3 entry, save SCTLR and TCR registers for EL1.
3. On EL3 entry, update EL1 system registers to disable stage 1
page table walk for lower ELs (EL1 and EL0) and enable EL1
MMU.
4. On EL3 exit, restore SCTLR and TCR registers for EL1 which
are saved in step 2.
[1]:
https://lists.trustedfirmware.org/pipermail/tf-a/2020-July/000586.html
Change-Id: Iee8de16f81dc970a8f492726f2ddd57e7bd9ffb5
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/bl31/aarch64/runtime_exceptions.S b/bl31/aarch64/runtime_exceptions.S
index 5b37388..bfe13f3 100644
--- a/bl31/aarch64/runtime_exceptions.S
+++ b/bl31/aarch64/runtime_exceptions.S
@@ -12,6 +12,7 @@
#include <bl31/interrupt_mgmt.h>
#include <common/runtime_svc.h>
#include <context.h>
+#include <el3_common_macros.S>
#include <lib/el3_runtime/cpu_data.h>
#include <lib/smccc.h>
@@ -285,21 +286,25 @@
* to a valid cpu context where the general purpose and system register
* state can be saved.
*/
+ apply_at_speculative_wa
check_and_unmask_ea
handle_sync_exception
end_vector_entry sync_exception_aarch64
vector_entry irq_aarch64
+ apply_at_speculative_wa
check_and_unmask_ea
handle_interrupt_exception irq_aarch64
end_vector_entry irq_aarch64
vector_entry fiq_aarch64
+ apply_at_speculative_wa
check_and_unmask_ea
handle_interrupt_exception fiq_aarch64
end_vector_entry fiq_aarch64
vector_entry serror_aarch64
+ apply_at_speculative_wa
msr daifclr, #DAIF_ABT_BIT
b enter_lower_el_async_ea
end_vector_entry serror_aarch64
@@ -315,21 +320,25 @@
* to a valid cpu context where the general purpose and system register
* state can be saved.
*/
+ apply_at_speculative_wa
check_and_unmask_ea
handle_sync_exception
end_vector_entry sync_exception_aarch32
vector_entry irq_aarch32
+ apply_at_speculative_wa
check_and_unmask_ea
handle_interrupt_exception irq_aarch32
end_vector_entry irq_aarch32
vector_entry fiq_aarch32
+ apply_at_speculative_wa
check_and_unmask_ea
handle_interrupt_exception fiq_aarch32
end_vector_entry fiq_aarch32
vector_entry serror_aarch32
+ apply_at_speculative_wa
msr daifclr, #DAIF_ABT_BIT
b enter_lower_el_async_ea
end_vector_entry serror_aarch32
@@ -455,6 +464,8 @@
b el3_exit
smc_prohibited:
+ restore_ptw_el1_sys_regs
+ ldp x28, x29, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_X28]
ldr x30, [sp, #CTX_GPREGS_OFFSET + CTX_GPREG_LR]
mov x0, #SMC_UNK
exception_return