Refactor ARMv8.3 Pointer Authentication support code
This patch provides the following features and makes modifications
listed below:
- Individual APIAKey key generation for each CPU.
- New key generation on every BL31 warm boot and TSP CPU On event.
- Per-CPU storage of APIAKey added in percpu_data[]
of cpu_data structure.
- `plat_init_apiakey()` function replaced with `plat_init_apkey()`
which returns 128-bit value and uses Generic timer physical counter
value to increase the randomness of the generated key.
The new function can be used for generation of all ARMv8.3-PAuth keys
- ARMv8.3-PAuth specific code placed in `lib\extensions\pauth`.
- New `pauth_init_enable_el1()` and `pauth_init_enable_el3()` functions
generate, program and enable APIAKey_EL1 for EL1 and EL3 respectively;
pauth_disable_el1()` and `pauth_disable_el3()` functions disable
PAuth for EL1 and EL3 respectively;
`pauth_load_bl31_apiakey()` loads saved per-CPU APIAKey_EL1 from
cpu-data structure.
- Combined `save_gp_pauth_registers()` function replaces calls to
`save_gp_registers()` and `pauth_context_save()`;
`restore_gp_pauth_registers()` replaces `pauth_context_restore()`
and `restore_gp_registers()` calls.
- `restore_gp_registers_eret()` function removed with corresponding
code placed in `el3_exit()`.
- Fixed the issue when `pauth_t pauth_ctx` structure allocated space
for 12 uint64_t PAuth registers instead of 10 by removal of macro
CTX_PACGAKEY_END from `include/lib/el3_runtime/aarch64/context.h`
and assigning its value to CTX_PAUTH_REGS_END.
- Use of MODE_SP_ELX and MODE_SP_EL0 macro definitions
in `msr spsel` instruction instead of hard-coded values.
- Changes in documentation related to ARMv8.3-PAuth and ARMv8.5-BTI.
Change-Id: Id18b81cc46f52a783a7e6a09b9f149b6ce803211
Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
diff --git a/plat/arm/common/aarch64/arm_pauth.c b/plat/arm/common/aarch64/arm_pauth.c
index a685c31..7cea8a0 100644
--- a/plat/arm/common/aarch64/arm_pauth.c
+++ b/plat/arm/common/aarch64/arm_pauth.c
@@ -4,27 +4,25 @@
* SPDX-License-Identifier: BSD-3-Clause
*/
+#include <arch_helpers.h>
#include <cdefs.h>
#include <stdint.h>
/*
- * Instruction pointer authentication key A. The low 64-bit are at [0], and the
- * high bits at [1].
+ * This is only a toy implementation to generate a seemingly random
+ * 128-bit key from sp, x30 and cntpct_el0 values.
+ * A production system must re-implement this function to generate
+ * keys from a reliable randomness source.
*/
-uint64_t plat_apiakey[2];
-
-/*
- * This is only a toy implementation to generate a seemingly random 128-bit key
- * from sp and x30 values. A production system must re-implement this function
- * to generate keys from a reliable randomness source.
- */
-uint64_t *plat_init_apiakey(void)
+uint128_t plat_init_apkey(void)
{
- uintptr_t return_addr = (uintptr_t)__builtin_return_address(0U);
- uintptr_t frame_addr = (uintptr_t)__builtin_frame_address(0U);
+ uint64_t return_addr = (uint64_t)__builtin_return_address(0U);
+ uint64_t frame_addr = (uint64_t)__builtin_frame_address(0U);
+ uint64_t cntpct = read_cntpct_el0();
- plat_apiakey[0] = (return_addr << 13) ^ frame_addr;
- plat_apiakey[1] = (frame_addr << 15) ^ return_addr;
+ /* Generate 128-bit key */
+ uint64_t key_lo = (return_addr << 13) ^ frame_addr ^ cntpct;
+ uint64_t key_hi = (frame_addr << 15) ^ return_addr ^ cntpct;
- return plat_apiakey;
+ return ((uint128_t)(key_hi) << 64) | key_lo;
}