linux-kernel - [PATCH arm64/kexec] arm64: kexec_file: forbid kdump via kexec_file

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Message-Id: <20181207101439.190918-1-james.morse@arm.com>
Date:   Fri,  7 Dec 2018 10:14:39 +0000
From:   James Morse <james.morse@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        kexec@...ts.infradead.org, Will Deacon <will.deacon@....com>,
        Rob Herring <robh+dt@...nel.org>,
        AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        David Howells <dhowells@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        David Miller <davem@...emloft.net>, dyoung@...hat.com,
        Baoquan He <bhe@...hat.com>, Arnd Bergmann <arnd@...db.de>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        prudo@...ux.ibm.com, Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        bhsharma@...hat.com, Frank Rowand <frowand.list@...il.com>,
        James Morse <james.morse@....com>
Subject: [PATCH arm64/kexec] arm64: kexec_file: forbid kdump via kexec_file_load()

Now that kexec_walk_memblock() can do the crash-kernel placement itself
architectures that don't support kdump via kexe_file_load() need to
explicitly forbid it.

We don't support this on arm64 until the kernel can add the elfcorehdr
and usable-memory-range fields to the DT. Without these the crash-kernel
overwrites the previous kernel's memory during startup.

Add a check to refuse crash image loading.

Signed-off-by: James Morse <james.morse@....com>
---

Context: http://lore.kernel.org/r/20181206155424.GA4422@arm.com

 arch/arm64/kernel/kexec_image.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/kernel/kexec_image.c b/arch/arm64/kernel/kexec_image.c
index 1ad1d5f8f024..07bf740bea91 100644
--- a/arch/arm64/kernel/kexec_image.c
+++ b/arch/arm64/kernel/kexec_image.c
@@ -47,6 +47,10 @@ static void *image_load(struct kimage *image,
 	struct kexec_segment *kernel_segment;
 	int ret;
 
+	/* We don't support crash kernels yet. */
+	if (image->type == KEXEC_TYPE_CRASH)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	/*
 	 * We require a kernel with an unambiguous Image header. Per
 	 * Documentation/booting.txt, this is the case when image_size
-- 
2.19.2