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8757dc970f
On x86 kernels configured with CONFIG_PROC_KCORE=y and CONFIG_KEXEC_CORE=n, the vmcoreinfo note in /proc/kcore is incomplete. Specifically, it is missing arch-specific information like the KASLR offset and whether 5-level page tables are enabled. This breaks applications like drgn [1] and crash [2], which need this information for live debugging via /proc/kcore. This happens because: 1. CONFIG_PROC_KCORE selects CONFIG_CRASH_CORE. 2. kernel/crash_core.c (compiled if CONFIG_CRASH_CORE=y) calls arch_crash_save_vmcoreinfo() to get the arch-specific parts of vmcoreinfo. If it is not defined, then it uses a no-op fallback. 3. x86 defines arch_crash_save_vmcoreinfo() in arch/x86/kernel/machine_kexec_*.c, which is only compiled if CONFIG_KEXEC_CORE=y. Therefore, an x86 kernel with CONFIG_CRASH_CORE=y and CONFIG_KEXEC_CORE=n uses the no-op fallback and gets incomplete vmcoreinfo data. This isn't relevant to kdump, which requires CONFIG_KEXEC_CORE. It only affects applications which read vmcoreinfo at runtime, like the ones mentioned above. Fix it by moving arch_crash_save_vmcoreinfo() into two new arch/x86/kernel/crash_core_*.c files, which are gated behind CONFIG_CRASH_CORE. 1:73dd7def12/libdrgn/program.c (L385)2:60a42d7092Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Andy Lutomirski <luto@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Kairui Song <kasong@redhat.com> Cc: Lianbo Jiang <lijiang@redhat.com> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: x86-ml <x86@kernel.org> Link: https://lkml.kernel.org/r/0589961254102cca23e3618b96541b89f2b249e2.1576858905.git.osandov@fb.com
25 lines
583 B
C
25 lines
583 B
C
// SPDX-License-Identifier: GPL-2.0-only
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#include <linux/crash_core.h>
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#include <asm/pgtable.h>
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#include <asm/setup.h>
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void arch_crash_save_vmcoreinfo(void)
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{
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u64 sme_mask = sme_me_mask;
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VMCOREINFO_NUMBER(phys_base);
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VMCOREINFO_SYMBOL(init_top_pgt);
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vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n",
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pgtable_l5_enabled());
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#ifdef CONFIG_NUMA
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VMCOREINFO_SYMBOL(node_data);
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VMCOREINFO_LENGTH(node_data, MAX_NUMNODES);
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#endif
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vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset());
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VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE);
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VMCOREINFO_NUMBER(sme_mask);
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}
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