From 203e9e41219b4e7357104e525e91ac609fba2c6c Mon Sep 17 00:00:00 2001 From: Xunlei Pang Date: Wed, 12 Jul 2017 14:33:14 -0700 Subject: kexec: move vmcoreinfo out of the kernel's .bss section As Eric said, "what we need to do is move the variable vmcoreinfo_note out of the kernel's .bss section. And modify the code to regenerate and keep this information in something like the control page. Definitely something like this needs a page all to itself, and ideally far away from any other kernel data structures. I clearly was not watching closely the data someone decided to keep this silly thing in the kernel's .bss section." This patch allocates extra pages for these vmcoreinfo_XXX variables, one advantage is that it enhances some safety of vmcoreinfo, because vmcoreinfo now is kept far away from other kernel data structures. Link: http://lkml.kernel.org/r/1493281021-20737-1-git-send-email-xlpang@redhat.com Signed-off-by: Xunlei Pang Tested-by: Michael Holzheu Reviewed-by: Juergen Gross Suggested-by: Eric Biederman Cc: Benjamin Herrenschmidt Cc: Dave Young Cc: Hari Bathini Cc: Mahesh Salgaonkar Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/crash_core.c | 26 ++++++++++++++++++++++---- 1 file changed, 22 insertions(+), 4 deletions(-) (limited to 'kernel/crash_core.c') diff --git a/kernel/crash_core.c b/kernel/crash_core.c index fcbd568f1e95..2837d6164db8 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -14,10 +14,10 @@ #include /* vmcoreinfo stuff */ -static unsigned char vmcoreinfo_data[VMCOREINFO_BYTES]; -u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4]; +static unsigned char *vmcoreinfo_data; size_t vmcoreinfo_size; -size_t vmcoreinfo_max_size = sizeof(vmcoreinfo_data); +size_t vmcoreinfo_max_size = VMCOREINFO_BYTES; +u32 *vmcoreinfo_note; /* * parsing the "crashkernel" commandline @@ -326,6 +326,9 @@ static void update_vmcoreinfo_note(void) void crash_save_vmcoreinfo(void) { + if (!vmcoreinfo_note) + return; + vmcoreinfo_append_str("CRASHTIME=%ld\n", get_seconds()); update_vmcoreinfo_note(); } @@ -356,11 +359,26 @@ void __weak arch_crash_save_vmcoreinfo(void) phys_addr_t __weak paddr_vmcoreinfo_note(void) { - return __pa_symbol((unsigned long)(char *)&vmcoreinfo_note); + return __pa(vmcoreinfo_note); } static int __init crash_save_vmcoreinfo_init(void) { + vmcoreinfo_data = (unsigned char *)get_zeroed_page(GFP_KERNEL); + if (!vmcoreinfo_data) { + pr_warn("Memory allocation for vmcoreinfo_data failed\n"); + return -ENOMEM; + } + + vmcoreinfo_note = alloc_pages_exact(VMCOREINFO_NOTE_SIZE, + GFP_KERNEL | __GFP_ZERO); + if (!vmcoreinfo_note) { + free_page((unsigned long)vmcoreinfo_data); + vmcoreinfo_data = NULL; + pr_warn("Memory allocation for vmcoreinfo_note failed\n"); + return -ENOMEM; + } + VMCOREINFO_OSRELEASE(init_uts_ns.name.release); VMCOREINFO_PAGESIZE(PAGE_SIZE); -- cgit v1.2.3