perf(cpus): inline the reset function

Similar to the cpu_rev_var and cpu_ger_rev_var functions, inline the
call_reset_handler handler. This way we skip the costly branch at no
extra cost as this is the only place where this is called.

While we're at it, drop the options for CPU_NO_RESET_FUNC. The only cpus
that need that are virtual cpus which can spare the tiny bit of
performance lost. The rest are real cores which can save on the check
for zero.

Now is a good time to put the assert for a missing cpu in the
get_cpu_ops_ptr function so that it's a bit better encapsulated.

Change-Id: Ia7c3dcd13b75e5d7c8bafad4698994ea65f42406
Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
diff --git a/docs/design/firmware-design.rst b/docs/design/firmware-design.rst
index cda80ca..975c1f2 100644
--- a/docs/design/firmware-design.rst
+++ b/docs/design/firmware-design.rst
@@ -247,7 +247,7 @@
 
 -  CPU initialization
 
-   BL1 calls the ``reset_handler()`` function which in turn calls the CPU
+   BL1 calls the ``reset_handler`` macro/function which in turn calls the CPU
    specific reset handler function (see the section: "CPU specific operations
    framework").
 
@@ -1337,7 +1337,7 @@
 
 TF-A implements a framework that allows CPU and platform ports to perform
 actions very early after a CPU is released from reset in both the cold and warm
-boot paths. This is done by calling the ``reset_handler()`` function in both
+boot paths. This is done by calling the ``reset_handler`` macro/function in both
 the BL1 and BL31 images. It in turn calls the platform and CPU specific reset
 handling functions.
 
@@ -2904,7 +2904,7 @@
 
 --------------
 
-*Copyright (c) 2013-2024, Arm Limited and Contributors. All rights reserved.*
+*Copyright (c) 2013-2025, Arm Limited and Contributors. All rights reserved.*
 
 .. _SMCCC: https://developer.arm.com/docs/den0028/latest
 .. _PSCI: https://developer.arm.com/documentation/den0022/latest/
diff --git a/include/arch/aarch64/asm_macros.S b/include/arch/aarch64/asm_macros.S
index ff01278..dce07d9 100644
--- a/include/arch/aarch64/asm_macros.S
+++ b/include/arch/aarch64/asm_macros.S
@@ -8,6 +8,7 @@
 
 #include <arch.h>
 #include <common/asm_macros_common.S>
+#include <lib/cpus/cpu_ops.h>
 #include <lib/spinlock.h>
 
 /*
@@ -340,4 +341,26 @@
 	mrs	\reg, ID_AA64ISAR2_EL1
 	ands	\reg, \reg, #(ID_AA64ISAR2_SYSREG128_MASK << ID_AA64ISAR2_SYSREG128_SHIFT)
 	.endm
+
+.macro call_reset_handler
+#if !(defined(IMAGE_BL2) && ENABLE_RME)
+	/* ---------------------------------------------------------------------
+	 * It is a cold boot.
+	 * Perform any processor specific actions upon reset e.g. cache, TLB
+	 * invalidations etc.
+	 * ---------------------------------------------------------------------
+	 */
+	/* The plat_reset_handler can clobber x0 - x18, x30 */
+	bl	plat_reset_handler
+
+	/* Get the matching cpu_ops pointer */
+	bl	get_cpu_ops_ptr
+
+	/* Get the cpu_ops reset handler */
+	ldr	x2, [x0, #CPU_RESET_FUNC]
+
+	/* The cpu_ops reset handler can clobber x0 - x19, x30 */
+	blr	x2
+#endif
+.endm
 #endif /* ASM_MACROS_S */
diff --git a/include/arch/aarch64/el2_common_macros.S b/include/arch/aarch64/el2_common_macros.S
index b9b0e3d..5db6831 100644
--- a/include/arch/aarch64/el2_common_macros.S
+++ b/include/arch/aarch64/el2_common_macros.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2021-2024, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2021-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -293,7 +293,7 @@
 	 * invalidations etc.
 	 * ---------------------------------------------------------------------
 	 */
-	bl	reset_handler
+	call_reset_handler
 
 	el2_arch_init_common
 
diff --git a/include/arch/aarch64/el3_common_macros.S b/include/arch/aarch64/el3_common_macros.S
index 204625c..fd16fb5 100644
--- a/include/arch/aarch64/el3_common_macros.S
+++ b/include/arch/aarch64/el3_common_macros.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -219,15 +219,7 @@
 	msr	vbar_el3, x0
 	isb
 
-#if !(defined(IMAGE_BL2) && ENABLE_RME)
-	/* ---------------------------------------------------------------------
-	 * It is a cold boot.
-	 * Perform any processor specific actions upon reset e.g. cache, TLB
-	 * invalidations etc.
-	 * ---------------------------------------------------------------------
-	 */
-	bl	reset_handler
-#endif
+	call_reset_handler
 
 	el3_arch_init_common
 
diff --git a/include/lib/cpus/aarch32/cpu_macros.S b/include/lib/cpus/aarch32/cpu_macros.S
index cfa5831..a878a5f 100644
--- a/include/lib/cpus/aarch32/cpu_macros.S
+++ b/include/lib/cpus/aarch32/cpu_macros.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -48,8 +48,7 @@
 	 * _midr:
 	 *	Numeric value expected to read from CPU's MIDR
 	 * _resetfunc:
-	 *	Reset function for the CPU. If there's no CPU reset function,
-	 *	specify CPU_NO_RESET_FUNC
+	 *	Reset function for the CPU
 	 * _power_down_ops:
 	 *	Comma-separated list of functions to perform power-down
 	 *	operatios on the CPU. At least one, and up to
diff --git a/include/lib/cpus/aarch64/cpu_macros.S b/include/lib/cpus/aarch64/cpu_macros.S
index 17592d3..c8f4bde 100644
--- a/include/lib/cpus/aarch64/cpu_macros.S
+++ b/include/lib/cpus/aarch64/cpu_macros.S
@@ -49,8 +49,7 @@
 	 * _midr:
 	 *	Numeric value expected to read from CPU's MIDR
 	 * _resetfunc:
-	 *	Reset function for the CPU. If there's no CPU reset function,
-	 *	specify CPU_NO_RESET_FUNC
+	 *	Reset function for the CPU.
 	 * _extra1:
 	 *	This is a placeholder for future per CPU operations.  Currently,
 	 *	some CPUs use this entry to set a test function to determine if
diff --git a/include/lib/cpus/cpu_ops.h b/include/lib/cpus/cpu_ops.h
index c1bdf8d..0b08919 100644
--- a/include/lib/cpus/cpu_ops.h
+++ b/include/lib/cpus/cpu_ops.h
@@ -21,8 +21,6 @@
 
 /* The number of CPU operations allowed */
 #define CPU_MAX_PWR_DWN_OPS		2
-/* Special constant to specify that CPU has no reset function */
-#define CPU_NO_RESET_FUNC		0
 
 #if __aarch64__
 #define CPU_NO_EXTRA1_FUNC		0
diff --git a/lib/cpus/aarch32/aem_generic.S b/lib/cpus/aarch32/aem_generic.S
index f4dc0d1..a424575 100644
--- a/lib/cpus/aarch32/aem_generic.S
+++ b/lib/cpus/aarch32/aem_generic.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2016-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -40,8 +40,11 @@
 	b	dcsw_op_all
 endfunc aem_generic_cluster_pwr_dwn
 
+func aem_generic_reset_func
+	bx	lr
+endfunc aem_generic_reset_func
 
 /* cpu_ops for Base AEM FVP */
-declare_cpu_ops aem_generic, BASE_AEM_MIDR, CPU_NO_RESET_FUNC, \
+declare_cpu_ops aem_generic, BASE_AEM_MIDR, aem_generic_reset_func, \
 	aem_generic_core_pwr_dwn, \
 	aem_generic_cluster_pwr_dwn
diff --git a/lib/cpus/aarch64/a64fx.S b/lib/cpus/aarch64/a64fx.S
index 4893a44..a53467a 100644
--- a/lib/cpus/aarch64/a64fx.S
+++ b/lib/cpus/aarch64/a64fx.S
@@ -29,12 +29,15 @@
 a64fx_regs:  /* The ascii list of register names to be reported */
         .asciz  ""
 
+cpu_reset_func_start a64fx
+cpu_reset_func_end a64fx
+
 func a64fx_cpu_reg_dump
         adr     x6, a64fx_regs
         ret
 endfunc a64fx_cpu_reg_dump
 
-declare_cpu_ops a64fx, A64FX_MIDR, CPU_NO_RESET_FUNC \
+declare_cpu_ops a64fx, A64FX_MIDR, a64fx_reset_func \
                 a64fx_core_pwr_dwn, \
                 a64fx_cluster_pwr_dwn
 
diff --git a/lib/cpus/aarch64/aem_generic.S b/lib/cpus/aarch64/aem_generic.S
index d5634cf..9002da6 100644
--- a/lib/cpus/aarch64/aem_generic.S
+++ b/lib/cpus/aarch64/aem_generic.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -74,6 +74,9 @@
 	b	dcsw_op_all
 endfunc aem_generic_cluster_pwr_dwn
 
+cpu_reset_func_start aem_generic
+cpu_reset_func_end aem_generic
+
 	/* ---------------------------------------------
 	 * This function provides cpu specific
 	 * register information for crash reporting.
@@ -94,11 +97,11 @@
 
 
 /* cpu_ops for Base AEM FVP */
-declare_cpu_ops aem_generic, BASE_AEM_MIDR, CPU_NO_RESET_FUNC, \
+declare_cpu_ops aem_generic, BASE_AEM_MIDR, aem_generic_reset_func, \
 	aem_generic_core_pwr_dwn, \
 	aem_generic_cluster_pwr_dwn
 
 /* cpu_ops for Foundation FVP */
-declare_cpu_ops aem_generic, FOUNDATION_AEM_MIDR, CPU_NO_RESET_FUNC, \
+declare_cpu_ops aem_generic, FOUNDATION_AEM_MIDR, aem_generic_reset_func, \
 	aem_generic_core_pwr_dwn, \
 	aem_generic_cluster_pwr_dwn
diff --git a/lib/cpus/aarch64/cpu_helpers.S b/lib/cpus/aarch64/cpu_helpers.S
index ead91c3..e608422 100644
--- a/lib/cpus/aarch64/cpu_helpers.S
+++ b/lib/cpus/aarch64/cpu_helpers.S
@@ -14,47 +14,6 @@
 #include <lib/cpus/errata.h>
 #include <lib/el3_runtime/cpu_data.h>
 
- /* Reset fn is needed in BL at reset vector */
-#if defined(IMAGE_BL1) || defined(IMAGE_BL31) ||	\
-	(defined(IMAGE_BL2) && RESET_TO_BL2)
-	/*
-	 * The reset handler common to all platforms.  After a matching
-	 * cpu_ops structure entry is found, the correponding reset_handler
-	 * in the cpu_ops is invoked.
-	 * Clobbers: x0 - x19, x30
-	 */
-	.globl	reset_handler
-func reset_handler
-	mov	x19, x30
-
-	/* The plat_reset_handler can clobber x0 - x18, x30 */
-	bl	plat_reset_handler
-
-	/* Get the matching cpu_ops pointer */
-	bl	get_cpu_ops_ptr
-
-#if ENABLE_ASSERTIONS
-	/*
-	 * Assert if invalid cpu_ops obtained. If this is not valid, it may
-	 * suggest that the proper CPU file hasn't been included.
-	 */
-	cmp	x0, #0
-	ASM_ASSERT(ne)
-#endif
-
-	/* Get the cpu_ops reset handler */
-	ldr	x2, [x0, #CPU_RESET_FUNC]
-	mov	x30, x19
-	cbz	x2, 1f
-
-	/* The cpu_ops reset handler can clobber x0 - x19, x30 */
-	br	x2
-1:
-	ret
-endfunc reset_handler
-
-#endif
-
 #ifdef IMAGE_BL31 /* The power down core and cluster is needed only in  BL31 */
 	/*
 	 * void prepare_cpu_pwr_dwn(unsigned int power_level)
@@ -213,6 +172,14 @@
 	b	1b
 error_exit:
 #endif
+#if ENABLE_ASSERTIONS
+	/*
+	 * Assert if invalid cpu_ops obtained. If this is not valid, it may
+	 * suggest that the proper CPU file hasn't been included.
+	 */
+	cmp	x0, #0
+	ASM_ASSERT(ne)
+#endif
 	ret
 endfunc get_cpu_ops_ptr
 
diff --git a/lib/cpus/aarch64/generic.S b/lib/cpus/aarch64/generic.S
index 5d7a857..849056f 100644
--- a/lib/cpus/aarch64/generic.S
+++ b/lib/cpus/aarch64/generic.S
@@ -80,7 +80,9 @@
  * ---------------------------------------------
  */
 .equ	generic_cpu_reg_dump,		0
-.equ	generic_reset_func,		0
+
+cpu_reset_func_start generic
+cpu_reset_func_end generic
 
 declare_cpu_ops generic, AARCH64_GENERIC_MIDR, \
 	generic_reset_func, \
diff --git a/lib/cpus/aarch64/qemu_max.S b/lib/cpus/aarch64/qemu_max.S
index fb03cf1..529bb4f 100644
--- a/lib/cpus/aarch64/qemu_max.S
+++ b/lib/cpus/aarch64/qemu_max.S
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2014-2024, Arm Limited and Contributors. All rights reserved.
+ * Copyright (c) 2014-2025, Arm Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -47,6 +47,9 @@
 	b	dcsw_op_all
 endfunc qemu_max_cluster_pwr_dwn
 
+cpu_reset_func_start qemu_max
+cpu_reset_func_end qemu_max
+
 	/* ---------------------------------------------
 	 * This function provides cpu specific
 	 * register information for crash reporting.
@@ -67,6 +70,6 @@
 
 
 /* cpu_ops for QEMU MAX */
-declare_cpu_ops qemu_max, QEMU_MAX_MIDR, CPU_NO_RESET_FUNC, \
+declare_cpu_ops qemu_max, QEMU_MAX_MIDR, qemu_max_reset_func, \
 	qemu_max_core_pwr_dwn, \
 	qemu_max_cluster_pwr_dwn