refactor(cm): clean up SCR_EL3 and CPTR_EL3 initialization
As with MDCR_EL3, setting some bits of these registers is redundant at
reset since they do not matter for EL3 execution and the registers get
context switched so they get overwritten anyway.
The SCR_EL3.{TWE, TWI, SMD, API, APK} bits only affect lower ELs so
their place is in context management. The API and APK bits are a bit
special as they would get implicitly unset for secure world when
CTX_INCLUDE_PAUTH_REGS is unset. This is now explicit with their normal
world values being always set as PAuth defaults to enabled. The same
sequence is also added to realm world too. The reasoning is the same as
for Secure world - PAuth will be enabled for NS, and unless explicitly
handled by firmware, it should not leak to realm.
The CPTR_EL3.{ESM, EZ, TAM} bits are set by the relevant
feat_enable()s in lib/extensions so they can be skipped too.
CPTR_EL3.TFP is special as it's needed for access to generic floating
point registers even when SVE is not present. So keep it but move to
context management.
This leaves CPTR_EL3.TCPAC which affects several extensions. This bit
was set centrally at reset, however the earliest need for it is in BL2.
So set it in cm_setup_context_common(). However, this CPTR_EL3 is only
restored for BL31 which is clearly not the case. So always restore it.
Finally, setting CPTR_EL3 to a fresh RESET_VAL for each security state
prevents any bits from leaking between them.
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
Change-Id: Ie7095e967bd4a6d6ca6acf314c7086d89fec8900
diff --git a/include/arch/aarch64/el3_common_macros.S b/include/arch/aarch64/el3_common_macros.S
index fa9310e..d15feb0 100644
--- a/include/arch/aarch64/el3_common_macros.S
+++ b/include/arch/aarch64/el3_common_macros.S
@@ -59,36 +59,14 @@
* zero here but are updated ahead of transitioning to a lower EL in the
* function cm_init_context_common().
*
- * SCR_EL3.TWE: Set to zero so that execution of WFE instructions at
- * EL2, EL1 and EL0 are not trapped to EL3.
- *
- * SCR_EL3.TWI: Set to zero so that execution of WFI instructions at
- * EL2, EL1 and EL0 are not trapped to EL3.
- *
* SCR_EL3.SIF: Set to one to disable instruction fetches from
* Non-secure memory.
*
- * SCR_EL3.SMD: Set to zero to enable SMC calls at EL1 and above, from
- * both Security states and both Execution states.
- *
* SCR_EL3.EA: Set to one to route External Aborts and SError Interrupts
* to EL3 when executing at any EL.
- *
- * SCR_EL3.{API,APK}: For Armv8.3 pointer authentication feature,
- * disable traps to EL3 when accessing key registers or using pointer
- * authentication instructions from lower ELs.
* ---------------------------------------------------------------------
*/
- mov_imm x0, ((SCR_RESET_VAL | SCR_EA_BIT | SCR_SIF_BIT) \
- & ~(SCR_TWE_BIT | SCR_TWI_BIT | SCR_SMD_BIT))
-#if CTX_INCLUDE_PAUTH_REGS
- /*
- * If the pointer authentication registers are saved during world
- * switches, enable pointer authentication everywhere, as it is safe to
- * do so.
- */
- orr x0, x0, #(SCR_API_BIT | SCR_APK_BIT)
-#endif
+ mov_imm x0, (SCR_RESET_VAL | SCR_EA_BIT | SCR_SIF_BIT)
#if ENABLE_RME
/*
* TODO: Settting the EEL2 bit to allow EL3 access to secure only registers
@@ -132,25 +110,9 @@
/* ---------------------------------------------------------------------
* Initialise CPTR_EL3, setting all fields rather than relying on hw.
* All fields are architecturally UNKNOWN on reset.
- *
- * CPTR_EL3.TCPAC: Set to zero so that any accesses to CPACR_EL1,
- * CPTR_EL2, CPACR, or HCPTR do not trap to EL3.
- *
- * CPTR_EL3.TFP: Set to zero so that accesses to the V- or Z- registers
- * by Advanced SIMD, floating-point or SVE instructions (if implemented)
- * do not trap to EL3.
- *
- * CPTR_EL3.TAM: Set to one so that Activity Monitor access is
- * trapped to EL3 by default.
- *
- * CPTR_EL3.EZ: Set to zero so that all SVE functionality is trapped
- * to EL3 by default.
- *
- * CPTR_EL3.ESM: Set to zero so that all SME functionality is trapped
- * to EL3 by default.
+ * ---------------------------------------------------------------------
*/
-
- mov_imm x0, (CPTR_EL3_RESET_VAL & ~(TCPAC_BIT | TFP_BIT))
+ mov_imm x0, CPTR_EL3_RESET_VAL
msr cptr_el3, x0
/*