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fix(smccc): check smc_fid [23:17] bits

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As per SMCCC spec Table 2.1 bit 23:17 must be zero (MBZ),
for all Fast Calls, when bit[31] == 1.
Adding this check to ensure SMC FIDs when get to the SMC handler
have these bits (23:17) cleared, if not capture and report them
as an unknown SMCs at the core.

Also the C runtime stack is copied to the stackpointer well in
advance, to leverage the existing el3_exit routine for unknown SMC.

Change-Id: I9972216db5ac164815011177945fb34dadc871b0
Signed-off-by: Jayanth Dodderi Chidanand <jayanthdodderi.chidanand@arm.com>
This commit is contained in:
Jayanth Dodderi Chidanand 2023-03-09 13:56:03 +00:00
parent c41b8e90f7
commit f8a35797b9
2 changed files with 22 additions and 8 deletions
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18
bl31/aarch64/runtime_exceptions.S
View file

@ -55,7 +55,7 @@
* delegated to platform EA handler.
*
* Without RAS_EXTENSION, this macro synchronizes pending errors using
* a DSB, unmasks Asynchronous External Aborts and saves X30 before
* a DSB, unmasks Asynchronous External Aborts and saves X30 before
* setting the flag CTX_IS_IN_EL3.
*/
.macro check_and_unmask_ea
@ -506,6 +506,17 @@ sync_handler64:
/* Copy SCR_EL3.NS bit to the flag to indicate caller's security */
bfi x7, x18, #0, #1
mov sp, x12
/*
* Per SMCCC documentation, bits [23:17] must be zero for Fast
* SMCs. Other values are reserved for future use. Ensure that
* these bits are zeroes, if not report as unknown SMC.
*/
tbz x0, #FUNCID_TYPE_SHIFT, 2f /* Skip check if its a Yield Call*/
tst x0, #(FUNCID_FC_RESERVED_MASK << FUNCID_FC_RESERVED_SHIFT)
b.ne smc_unknown
/*
* Per SMCCCv1.3 a caller can set the SVE hint bit in the SMC FID
* passed through x0. Copy the SVE hint bit to flags and mask the
@ -513,11 +524,10 @@ sync_handler64:
* A service/dispatcher can retrieve the SVE hint bit state from
* flags using the appropriate helper.
*/
2:
bfi x7, x0, #FUNCID_SVE_HINT_SHIFT, #FUNCID_SVE_HINT_MASK
bic x0, x0, #(FUNCID_SVE_HINT_MASK << FUNCID_SVE_HINT_SHIFT)
mov sp, x12
/* Get the unique owning entity number */
ubfx x16, x0, #FUNCID_OEN_SHIFT, #FUNCID_OEN_WIDTH
ubfx x15, x0, #FUNCID_TYPE_SHIFT, #FUNCID_TYPE_WIDTH
@ -584,7 +594,7 @@ smc_unknown:
* Unknown SMC call. Populate return value with SMC_UNK and call
* el3_exit() which will restore the remaining architectural state
* i.e., SYS, GP and PAuth registers(if any) prior to issuing the ERET
* to the desired lower EL.
* to the desired lower EL.
*/
mov x0, #SMC_UNK
str x0, [x6, #CTX_GPREGS_OFFSET + CTX_GPREG_X0]

12
include/lib/smccc.h
View file

@ -1,5 +1,5 @@
/*
* Copyright (c) 2016-2022, ARM Limited and Contributors. All rights reserved.
* Copyright (c) 2016-2023, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
@ -37,9 +37,13 @@
#define FUNCID_OEN_MASK U(0x3f)
#define FUNCID_OEN_WIDTH U(6)
#define FUNCID_SVE_HINT_SHIFT U(16)
#define FUNCID_SVE_HINT_MASK U(1)
#define FUNCID_SVE_HINT_WIDTH U(1)
#define FUNCID_FC_RESERVED_SHIFT U(17)
#define FUNCID_FC_RESERVED_MASK U(0x7f)
#define FUNCID_FC_RESERVED_WIDTH U(7)
#define FUNCID_SVE_HINT_SHIFT U(16)
#define FUNCID_SVE_HINT_MASK U(1)
#define FUNCID_SVE_HINT_WIDTH U(1)
#define FUNCID_NUM_SHIFT U(0)
#define FUNCID_NUM_MASK U(0xffff)