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Date:   Wed, 28 Sep 2022 18:38:53 +0200
From:   Borislav Petkov <bp@alien8.de>
To:     Eric DeVolder <eric.devolder@oracle.com>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        kexec@lists.infradead.org, ebiederm@xmission.com,
        dyoung@redhat.com, bhe@redhat.com, vgoyal@redhat.com,
        tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com,
        hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com,
        robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com,
        sourabhjain@linux.ibm.com, konrad.wilk@oracle.com,
        boris.ostrovsky@oracle.com
Subject: Re: [PATCH v12 7/7] x86/crash: Add x86 crash hotplug support
Message-ID: <YzR4neYLNB8tByNa@zn.tnic>
References: <20220909210509.6286-1-eric.devolder@oracle.com>
 <20220909210509.6286-8-eric.devolder@oracle.com>
 <Yx7XEcXZ8PwwQW95@nazgul.tnic>
 <cb343eef-46be-2d67-b93a-84c75be86325@oracle.com>
 <YzRxPAoN+XmOfJzV@zn.tnic>
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On Wed, Sep 28, 2022 at 06:07:24PM +0200, Borislav Petkov wrote:
>  #if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
>  	/* Ensure elfcorehdr segment large enough for hotplug changes */
> @@ -407,9 +408,8 @@ int crash_load_segments(struct kimage *image)
>  	image->elf_headers_sz = kbuf.memsz;
>  	image->elfcorehdr_index = image->nr_segments;
>  	image->elfcorehdr_index_valid = true;

And that ifdeffery above can be made more readable too:

diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index a526c893abe8..7aab6e942761 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -399,16 +399,15 @@ int crash_load_segments(struct kimage *image)
 	image->elf_headers_sz	= kbuf.bufsz;
 	kbuf.memsz		= kbuf.bufsz;
 
-#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
 	/* Ensure elfcorehdr segment large enough for hotplug changes */
-	kbuf.memsz =
-		(CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES) *
-			sizeof(Elf64_Phdr);
-	/* Mark as usable to crash kernel, else crash kernel fails on boot */
-	image->elf_headers_sz = kbuf.memsz;
-	image->elfcorehdr_index = image->nr_segments;
-	image->elfcorehdr_index_valid = true;
-#endif
+	if (IS_ENABLED(CONFIG_CRASH_MAX_MEMORY_RANGES)) {
+		kbuf.memsz = (CONFIG_NR_CPUS_DEFAULT + CONFIG_CRASH_MAX_MEMORY_RANGES) * sizeof(Elf64_Phdr);
+
+		/* Mark as usable to crash kernel, else crash kernel fails on boot */
+		image->elf_headers_sz = kbuf.memsz;
+		image->elfcorehdr_index = image->nr_segments;
+		image->elfcorehdr_index_valid = true;
+	}
 
 	kbuf.buf_align = ELF_CORE_HEADER_ALIGN;
 	kbuf.mem = KEXEC_BUF_MEM_UNKNOWN;

-- 
Regards/Gruss,
    Boris.

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