Make PAC demangling more generic

At the moment, address demangling is only used by the backtrace
functionality. However, at some point, other parts of the TF-A
codebase may want to use it.
The 'demangle_address' function is replaced with a single XPACI
instruction which is also added in 'do_crash_reporting()'.

Signed-off-by: Alexei Fedorov <Alexei.Fedorov@arm.com>
Change-Id: I4424dcd54d5bf0a5f9b2a0a84c4e565eec7329ec

1 files changed, 3 insertions, 46 deletions

diff --git a/common/backtrace/backtrace.c b/common/backtrace/backtrace.c
index 506d4a482..907117f36 100644
--- a/common/backtrace/backtrace.c
+++ b/common/backtrace/backtrace.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2018-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -37,47 +37,6 @@ struct frame_record {
 	uintptr_t return_addr;
 };
 
-/*
- * Strip the Pointer Authentication Code (PAC) from the address to retrieve the
- * original one.
- *
- * The PAC field is stored on the high bits of the address and defined as:
- * - PAC field = Xn[54:bottom_PAC_bit], when address tagging is used.
- * - PAC field = Xn[63:56, 54:bottom_PAC_bit], without address tagging.
- *
- * With bottom_PAC_bit = 64 - TCR_ELx.TnSZ
- */
-#if ENABLE_PAUTH
-static uintptr_t demangle_address(uintptr_t addr)
-{
-	unsigned int el, t0sz, bottom_pac_bit;
-	uint64_t tcr, pac_mask;
-
-	/*
-	 * Different virtual address space size can be defined for each EL.
-	 * Ensure that we use the proper one by reading the corresponding
-	 * TCR_ELx register.
-	 */
-	el = get_current_el();
-
-	if (el == 3U) {
-		tcr = read_tcr_el3();
-	} else if (el == 2U) {
-		tcr = read_tcr_el2();
-	} else {
-		tcr = read_tcr_el1();
-	}
-
-	/* T0SZ = TCR_ELx[5:0] */
-	t0sz = tcr & 0x1f;
-	bottom_pac_bit = 64 - t0sz;
-	pac_mask = (1ULL << bottom_pac_bit) - 1;
-
-	/* demangle the address with the computed mask */
-	return (addr & pac_mask);
-}
-#endif /* ENABLE_PAUTH */
-
 static const char *get_el_str(unsigned int el)
 {
 	if (el == 3U) {
@@ -104,9 +63,8 @@ static bool is_address_readable(uintptr_t addr)
 	 * stack contains a PAC. It must be stripped to retrieve the return
 	 * address.
 	 */
-	addr = demangle_address(addr);
+	xpaci(addr);
 #endif
-
 	if (el == 3U) {
 		ats1e3r(addr);
 	} else if (el == 2U) {
@@ -257,9 +215,8 @@ static void unwind_stack(struct frame_record *fr, uintptr_t current_pc,
 		 * the stack contains a PAC. It must be stripped to retrieve the
 		 * return address.
 		 */
-		call_site = demangle_address(call_site);
+		xpaci(call_site);
 #endif
-
 		/*
 		 * If the address is invalid it means that the frame record is
 		 * probably corrupted.