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

bl31/aarch64/crash_reporting.S

 /*
- * Copyright (c) 2014-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -244,6 +244,11 @@ func do_crash_reporting
 	mrs	x0, tpidr_el3
 	/* report x30 first from the crash buf */
 	ldr	x4, [x0, #REGSZ * 7]
+
+#if ENABLE_PAUTH
+	/* Demangle address */
+	xpaci	x4
+#endif
 	bl	asm_print_hex
 	bl	asm_print_newline
 	/* Load the crash buf address */

common/backtrace/backtrace.c

 /*
- * 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.

docs/getting_started/build-options.rst

@@ -189,7 +189,7 @@ Common build options
    that is only required for the assertion and does not fit in the assertion
    itself.
 
--  ``ENABLE_BACKTRACE``: This option controls whether to enables backtrace
+-  ``ENABLE_BACKTRACE``: This option controls whether to enable backtrace
    dumps or not. It is supported in both AArch64 and AArch32. However, in
    AArch32 the format of the frame records are not defined in the AAPCS and they
    are defined by the implementation. This implementation of backtrace only

include/arch/aarch64/arch_helpers.h

 /*
- * Copyright (c) 2013-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2013-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -69,6 +69,13 @@ static inline void _op(void)				\
 	__asm__ (#_op);					\
 }
 
+/* Define function for system instruction with register parameter */
+#define DEFINE_SYSOP_PARAM_FUNC(_op)			\
+static inline void _op(uint64_t v)			\
+{							\
+	 __asm__ (#_op "  %0" : : "r" (v));		\
+}
+
 /* Define function for system instruction with type specifier */
 #define DEFINE_SYSOP_TYPE_FUNC(_op, _type)		\
 static inline void _op ## _type(void)			\
@@ -211,6 +218,11 @@ DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s1e1r)
 DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s1e2r)
 DEFINE_SYSOP_TYPE_PARAM_FUNC(at, s1e3r)
 
+/*******************************************************************************
+ * Strip Pointer Authentication Code
+ ******************************************************************************/
+DEFINE_SYSOP_PARAM_FUNC(xpaci)
+
 void flush_dcache_range(uintptr_t addr, size_t size);
 void clean_dcache_range(uintptr_t addr, size_t size);
 void inv_dcache_range(uintptr_t addr, size_t size);