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From:   Max Filippov <jcmvbkbc@gmail.com>
To:     linux-xtensa@linux-xtensa.org
Cc:     Chris Zankel <chris@zankel.net>, linux-kernel@vger.kernel.org,
        Max Filippov <jcmvbkbc@gmail.com>
Subject: [PATCH] xtensa: make secondary reset vector support conditional
Date:   Wed,  9 Mar 2022 16:59:35 -0800
Message-Id: <20220310005935.1260003-1-jcmvbkbc@gmail.com>
MIME-Version: 1.0
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Precedence: bulk

Whether xtensa cores start from primary or secondary reset vector is
configurable and may be chosen by board designer or controlled at
runtime. When secondary reset vector is unused its location in memory
may not be writable.
Make secondary reset vector support conditional and don't build and load
secondary reset vector code when it is disabled.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
---
 arch/xtensa/Kconfig              | 9 +++++++++
 arch/xtensa/kernel/Makefile      | 3 ++-
 arch/xtensa/kernel/setup.c       | 2 +-
 arch/xtensa/kernel/vmlinux.lds.S | 4 ++--
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
index cf03ed54c8f0..a02c3388f521 100644
--- a/arch/xtensa/Kconfig
+++ b/arch/xtensa/Kconfig
@@ -227,6 +227,15 @@ config HOTPLUG_CPU
 
 	  Say N if you want to disable CPU hotplug.
 
+config SECONDARY_RESET_VECTOR
+	bool "Secondary cores use alternative reset vector"
+	default y
+	depends on HAVE_SMP
+	help
+	  Secondary cores may be configured to use alternative reset vector,
+	  or all cores may use primary reset vector.
+	  Say Y here to supply handler for the alternative reset location.
+
 config FAST_SYSCALL_XTENSA
 	bool "Enable fast atomic syscalls"
 	default n
diff --git a/arch/xtensa/kernel/Makefile b/arch/xtensa/kernel/Makefile
index d4082c6a121b..5fd6cd15e0fb 100644
--- a/arch/xtensa/kernel/Makefile
+++ b/arch/xtensa/kernel/Makefile
@@ -13,7 +13,8 @@ obj-$(CONFIG_MMU) += pci-dma.o
 obj-$(CONFIG_PCI) += pci.o
 obj-$(CONFIG_MODULES) += xtensa_ksyms.o module.o
 obj-$(CONFIG_FUNCTION_TRACER) += mcount.o
-obj-$(CONFIG_SMP) += smp.o mxhead.o
+obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_SECONDARY_RESET_VECTOR) += mxhead.o
 obj-$(CONFIG_XTENSA_VARIANT_HAVE_PERF_EVENTS) += perf_event.o
 obj-$(CONFIG_HAVE_HW_BREAKPOINT) += hw_breakpoint.o
 obj-$(CONFIG_S32C1I_SELFTEST) += s32c1i_selftest.o
diff --git a/arch/xtensa/kernel/setup.c b/arch/xtensa/kernel/setup.c
index 3f1842891482..9191738f9941 100644
--- a/arch/xtensa/kernel/setup.c
+++ b/arch/xtensa/kernel/setup.c
@@ -349,7 +349,7 @@ void __init setup_arch(char **cmdline_p)
 
 #endif /* CONFIG_VECTORS_ADDR */
 
-#ifdef CONFIG_SMP
+#ifdef CONFIG_SECONDARY_RESET_VECTOR
 	mem_reserve(__pa(_SecondaryResetVector_text_start),
 		    __pa(_SecondaryResetVector_text_end));
 #endif
diff --git a/arch/xtensa/kernel/vmlinux.lds.S b/arch/xtensa/kernel/vmlinux.lds.S
index eee270a039a4..965a3952c47b 100644
--- a/arch/xtensa/kernel/vmlinux.lds.S
+++ b/arch/xtensa/kernel/vmlinux.lds.S
@@ -207,7 +207,7 @@ SECTIONS
     RELOCATE_ENTRY(_xip_data, .data);
     RELOCATE_ENTRY(_xip_init_data, .init.data);
 #endif
-#if defined(CONFIG_SMP)
+#if defined(CONFIG_SECONDARY_RESET_VECTOR)
     RELOCATE_ENTRY(_SecondaryResetVector_text,
 		   .SecondaryResetVector.text);
 #endif
@@ -303,7 +303,7 @@ SECTIONS
 #define LAST .DoubleExceptionVector.text
 
 #endif
-#if defined(CONFIG_SMP)
+#if defined(CONFIG_SECONDARY_RESET_VECTOR)
 
   SECTION_VECTOR4 (_SecondaryResetVector_text,
 		  .SecondaryResetVector.text,
-- 
2.30.2