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Date:   Mon, 4 Dec 2023 10:19:36 +0800
From:   Baoquan He <bhe@redhat.com>
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>, akpm@linux-foundation.org,
        ignat@cloudflare.com, linux-next@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org,
        kexec@lists.infradead.org, eric_devolder@yahoo.com
Subject: [PATCH 1/2] riscv, crash: don't export some symbols when CONFIG_MMU=n
Message-ID: <ZW03ODUKGGhP1ZGU@MiWiFi-R3L-srv>
References: <ZW00/Cfk47Cc3kGo@MiWiFi-R3L-srv>
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In-Reply-To: <ZW00/Cfk47Cc3kGo@MiWiFi-R3L-srv>
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When dropping select of KEXEC and dependency on ARCH_SUPPORTS_KEXEC
from CRASH_DUMP, compiling error is reported when below config items are
set:
-----------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
......
-----------------------

-------------------------------------------------------------------------------------------------
arch/riscv/kernel/crash_core.c:8:27: error: 'VA_BITS' undeclared (first use in this function)
 8 |         VMCOREINFO_NUMBER(VA_BITS);
   |                           ^~~~~~~
include/linux/crash_core.h:78:64: note: in definition of macro 'VMCOREINFO_NUMBER'
78 |         vmcoreinfo_append_str("NUMBER(%s)=%ld\n", #name, (long)name)
   |                                                                ^~~~

arch/riscv/kernel/crash_core.c:14:64: error: 'VMEMMAP_START' undeclared (first use in this function)
14 |         vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", VMEMMAP_START);
   |                                                                ^~~~~~~~~~~~~
arch/riscv/kernel/crash_core.c:15:62: error: 'VMEMMAP_END' undeclared (first use in this function); did you mean 'MEMREMAP_ENC'?
15 |         vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END);
   |                                                              ^~~~~~~~~~~
   |                                                              MEMREMAP_ENC
arch/riscv/kernel/crash_core.c:17:64: error: 'MODULES_VADDR' undeclared (first use in this function)
17 |         vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
   |                                                                ^~~~~~~~~~~~~
arch/riscv/kernel/crash_core.c:18:62: error: 'MODULES_END' undeclared (first use in this function)
18 |         vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
-------------------------------------------------------------------------------------------------

Currently, riscv's ARCH_SUPPORTS_KEXEC has dependency on MMU. Before
dropping ARCH_SUPPORTS_KEXEC, disabling CONFIG_MMU will unset
CONFIG_CRASH_DUMP, CONFIG_KEXEC_CORE, CONFIG_CRASH_CORE. Hence
crash_core related codes won't be compiled.

---------------------
arch/riscv/Kconfig:
config ARCH_SUPPORTS_KEXEC
        def_bool MMU
---------------------

After dropping ARCH_SUPPORTS_KEXEC, CONFIG_CRASH_DUMP, CONFIG_KEXEC_CORE,
CONFIG_CRASH_CORE can be set independently of CONFIG_MMU. However, there
are several macro definitions, such as VA_BITS, VMEMMAP_START, VMEMMAP_END,
MODULES_VADDR, MODULES_END are only available when CONFIG_MMU=y. Then
compiling errors are triggered.

Here, add CONFIG_MMU ifdeffery in arch_crash_save_vmcoreinfo() to export
those symbols when CONFIG_MMU is enabled.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 arch/riscv/kernel/crash_core.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/riscv/kernel/crash_core.c b/arch/riscv/kernel/crash_core.c
index 55f1d7856b54..8706736fd4e2 100644
--- a/arch/riscv/kernel/crash_core.c
+++ b/arch/riscv/kernel/crash_core.c
@@ -5,17 +5,19 @@
 
 void arch_crash_save_vmcoreinfo(void)
 {
-	VMCOREINFO_NUMBER(VA_BITS);
 	VMCOREINFO_NUMBER(phys_ram_base);
 
 	vmcoreinfo_append_str("NUMBER(PAGE_OFFSET)=0x%lx\n", PAGE_OFFSET);
 	vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
 	vmcoreinfo_append_str("NUMBER(VMALLOC_END)=0x%lx\n", VMALLOC_END);
+#ifdef CONFIG_MMU
+	VMCOREINFO_NUMBER(VA_BITS);
 	vmcoreinfo_append_str("NUMBER(VMEMMAP_START)=0x%lx\n", VMEMMAP_START);
 	vmcoreinfo_append_str("NUMBER(VMEMMAP_END)=0x%lx\n", VMEMMAP_END);
 #ifdef CONFIG_64BIT
 	vmcoreinfo_append_str("NUMBER(MODULES_VADDR)=0x%lx\n", MODULES_VADDR);
 	vmcoreinfo_append_str("NUMBER(MODULES_END)=0x%lx\n", MODULES_END);
+#endif
 #endif
 	vmcoreinfo_append_str("NUMBER(KERNEL_LINK_ADDR)=0x%lx\n", KERNEL_LINK_ADDR);
 	vmcoreinfo_append_str("NUMBER(va_kernel_pa_offset)=0x%lx\n",
-- 
2.41.0