Commit 203e9e41 authored by Xunlei Pang's avatar Xunlei Pang Committed by Linus Torvalds

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.comSigned-off-by: 's avatarXunlei Pang <xlpang@redhat.com>
Tested-by: 's avatarMichael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: 's avatarJuergen Gross <jgross@suse.com>
Suggested-by: 's avatarEric Biederman <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Dave Young <dyoung@redhat.com>
Cc: Hari Bathini <hbathini@linux.vnet.ibm.com>
Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>
Signed-off-by: 's avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: 's avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 112166f8
......@@ -163,8 +163,3 @@ void arch_crash_save_vmcoreinfo(void)
#endif
}
phys_addr_t paddr_vmcoreinfo_note(void)
{
return ia64_tpa((unsigned long)(char *)&vmcoreinfo_note);
}
......@@ -246,6 +246,7 @@ void arch_crash_save_vmcoreinfo(void)
VMCOREINFO_SYMBOL(lowcore_ptr);
VMCOREINFO_SYMBOL(high_memory);
VMCOREINFO_LENGTH(lowcore_ptr, NR_CPUS);
mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
}
void machine_shutdown(void)
......
......@@ -496,11 +496,6 @@ static void __init setup_memory_end(void)
pr_notice("The maximum memory size is %luMB\n", memory_end >> 20);
}
static void __init setup_vmcoreinfo(void)
{
mem_assign_absolute(S390_lowcore.vmcore_info, paddr_vmcoreinfo_note());
}
#ifdef CONFIG_CRASH_DUMP
/*
......@@ -939,7 +934,6 @@ void __init setup_arch(char **cmdline_p)
#endif
setup_resources();
setup_vmcoreinfo();
setup_lowcore();
smp_fill_possible_mask();
cpu_detect_mhz_feature();
......
......@@ -457,7 +457,7 @@ static int prepare_elf64_headers(struct crash_elf_data *ced,
bufp += sizeof(Elf64_Phdr);
phdr->p_type = PT_NOTE;
phdr->p_offset = phdr->p_paddr = paddr_vmcoreinfo_note();
phdr->p_filesz = phdr->p_memsz = sizeof(vmcoreinfo_note);
phdr->p_filesz = phdr->p_memsz = VMCOREINFO_NOTE_SIZE;
(ehdr->e_phnum)++;
#ifdef CONFIG_X86_64
......
......@@ -2693,8 +2693,8 @@ EXPORT_SYMBOL_GPL(xen_destroy_contiguous_region);
phys_addr_t paddr_vmcoreinfo_note(void)
{
if (xen_pv_domain())
return virt_to_machine(&vmcoreinfo_note).maddr;
return virt_to_machine(vmcoreinfo_note).maddr;
else
return __pa_symbol(&vmcoreinfo_note);
return __pa(vmcoreinfo_note);
}
#endif /* CONFIG_KEXEC_CORE */
......@@ -19,7 +19,7 @@
CRASH_CORE_NOTE_NAME_BYTES + \
CRASH_CORE_NOTE_DESC_BYTES)
#define VMCOREINFO_BYTES (4096)
#define VMCOREINFO_BYTES PAGE_SIZE
#define VMCOREINFO_NOTE_NAME "VMCOREINFO"
#define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4)
#define VMCOREINFO_NOTE_SIZE ((CRASH_CORE_NOTE_HEAD_BYTES * 2) + \
......@@ -56,7 +56,7 @@ phys_addr_t paddr_vmcoreinfo_note(void);
#define VMCOREINFO_CONFIG(name) \
vmcoreinfo_append_str("CONFIG_%s=y\n", #name)
extern u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
extern u32 *vmcoreinfo_note;
extern size_t vmcoreinfo_size;
extern size_t vmcoreinfo_max_size;
......
......@@ -14,10 +14,10 @@
#include <asm/sections.h>
/* 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);
......
......@@ -134,7 +134,7 @@ static ssize_t vmcoreinfo_show(struct kobject *kobj,
{
phys_addr_t vmcore_base = paddr_vmcoreinfo_note();
return sprintf(buf, "%pa %x\n", &vmcore_base,
(unsigned int)sizeof(vmcoreinfo_note));
(unsigned int)VMCOREINFO_NOTE_SIZE);
}
KERNEL_ATTR_RO(vmcoreinfo);
......
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