From 8757dc970f550dc399f899be0e7a2c00b7e82e8f Mon Sep 17 00:00:00 2001 From: Omar Sandoval Date: Fri, 20 Dec 2019 08:22:49 -0800 Subject: [PATCH] x86/crash: Define arch_crash_save_vmcoreinfo() if CONFIG_CRASH_CORE=y 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: https://github.com/osandov/drgn/blob/73dd7def1217e24cc83d8ca95c995decbd9ba24c/libdrgn/program.c#L385 2: https://github.com/crash-utility/crash/commit/60a42d709280cdf38ab06327a5b4fa9d9208ef86 Signed-off-by: Omar Sandoval Signed-off-by: Borislav Petkov Cc: Andy Lutomirski Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Kairui Song Cc: Lianbo Jiang Cc: Masahiro Yamada Cc: "Peter Zijlstra (Intel)" Cc: Thomas Gleixner Cc: x86-ml Link: https://lkml.kernel.org/r/0589961254102cca23e3618b96541b89f2b249e2.1576858905.git.osandov@fb.com --- arch/x86/kernel/Makefile | 1 + arch/x86/kernel/crash_core_32.c | 17 +++++++++++++++++ arch/x86/kernel/crash_core_64.c | 24 ++++++++++++++++++++++++ arch/x86/kernel/machine_kexec_32.c | 12 ------------ arch/x86/kernel/machine_kexec_64.c | 19 ------------------- 5 files changed, 42 insertions(+), 31 deletions(-) create mode 100644 arch/x86/kernel/crash_core_32.c create mode 100644 arch/x86/kernel/crash_core_64.c diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 6175e370ee4a..9b294c13809a 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -94,6 +94,7 @@ obj-$(CONFIG_FUNCTION_TRACER) += ftrace_$(BITS).o obj-$(CONFIG_FUNCTION_GRAPH_TRACER) += ftrace.o obj-$(CONFIG_FTRACE_SYSCALLS) += ftrace.o obj-$(CONFIG_X86_TSC) += trace_clock.o +obj-$(CONFIG_CRASH_CORE) += crash_core_$(BITS).o obj-$(CONFIG_KEXEC_CORE) += machine_kexec_$(BITS).o obj-$(CONFIG_KEXEC_CORE) += relocate_kernel_$(BITS).o crash.o obj-$(CONFIG_KEXEC_FILE) += kexec-bzimage64.o diff --git a/arch/x86/kernel/crash_core_32.c b/arch/x86/kernel/crash_core_32.c new file mode 100644 index 000000000000..c0159a7bca6d --- /dev/null +++ b/arch/x86/kernel/crash_core_32.c @@ -0,0 +1,17 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include + +#include +#include + +void arch_crash_save_vmcoreinfo(void) +{ +#ifdef CONFIG_NUMA + VMCOREINFO_SYMBOL(node_data); + VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); +#endif +#ifdef CONFIG_X86_PAE + VMCOREINFO_CONFIG(X86_PAE); +#endif +} diff --git a/arch/x86/kernel/crash_core_64.c b/arch/x86/kernel/crash_core_64.c new file mode 100644 index 000000000000..845a57eb4eb7 --- /dev/null +++ b/arch/x86/kernel/crash_core_64.c @@ -0,0 +1,24 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include + +#include +#include + +void arch_crash_save_vmcoreinfo(void) +{ + u64 sme_mask = sme_me_mask; + + VMCOREINFO_NUMBER(phys_base); + VMCOREINFO_SYMBOL(init_top_pgt); + vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n", + pgtable_l5_enabled()); + +#ifdef CONFIG_NUMA + VMCOREINFO_SYMBOL(node_data); + VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); +#endif + vmcoreinfo_append_str("KERNELOFFSET=%lx\n", kaslr_offset()); + VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE); + VMCOREINFO_NUMBER(sme_mask); +} diff --git a/arch/x86/kernel/machine_kexec_32.c b/arch/x86/kernel/machine_kexec_32.c index 7b45e8daad22..02bddfc122a4 100644 --- a/arch/x86/kernel/machine_kexec_32.c +++ b/arch/x86/kernel/machine_kexec_32.c @@ -250,15 +250,3 @@ void machine_kexec(struct kimage *image) __ftrace_enabled_restore(save_ftrace_enabled); } - -void arch_crash_save_vmcoreinfo(void) -{ -#ifdef CONFIG_NUMA - VMCOREINFO_SYMBOL(node_data); - VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); -#endif -#ifdef CONFIG_X86_PAE - VMCOREINFO_CONFIG(X86_PAE); -#endif -} - diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index 16e125a50b33..ad5cdd6a5f23 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -398,25 +398,6 @@ void machine_kexec(struct kimage *image) __ftrace_enabled_restore(save_ftrace_enabled); } -void arch_crash_save_vmcoreinfo(void) -{ - u64 sme_mask = sme_me_mask; - - VMCOREINFO_NUMBER(phys_base); - VMCOREINFO_SYMBOL(init_top_pgt); - vmcoreinfo_append_str("NUMBER(pgtable_l5_enabled)=%d\n", - pgtable_l5_enabled()); - -#ifdef CONFIG_NUMA - VMCOREINFO_SYMBOL(node_data); - VMCOREINFO_LENGTH(node_data, MAX_NUMNODES); -#endif - vmcoreinfo_append_str("KERNELOFFSET=%lx\n", - kaslr_offset()); - VMCOREINFO_NUMBER(KERNEL_IMAGE_SIZE); - VMCOREINFO_NUMBER(sme_mask); -} - /* arch-dependent functionality related to kexec file-based syscall */ #ifdef CONFIG_KEXEC_FILE