From 203e9e41219b4e7357104e525e91ac609fba2c6c Mon Sep 17 00:00:00 2001
From: Xunlei Pang <xlpang@redhat.com>
Date: Wed, 12 Jul 2017 14:33:14 -0700
Subject: [PATCH] kexec: move vmcoreinfo out of the kernel's .bss section
References: bsc#1051137
Patch-mainline: v4.13-rc1
Git-commit: 203e9e41219b4e7357104e525e91ac609fba2c6c
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 <xlpang@redhat.com>
Tested-by: Michael Holzheu <holzheu@linux.vnet.ibm.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Suggested-by: Eric 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
arch/ia64/kernel/machine_kexec.c | 5 -----
arch/s390/kernel/machine_kexec.c | 1 +
arch/s390/kernel/setup.c | 6 ------
arch/x86/kernel/crash.c | 2 +-
arch/x86/xen/mmu_pv.c | 4 ++--
include/linux/crash_core.h | 4 ++--
kernel/crash_core.c | 26 ++++++++++++++++++++++----
kernel/ksysfs.c | 2 +-
8 files changed, 29 insertions(+), 21 deletions(-)
diff --git a/arch/ia64/kernel/machine_kexec.c b/arch/ia64/kernel/machine_kexec.c
index 599507bcec91..c14815dca747 100644
--- a/arch/ia64/kernel/machine_kexec.c
+++ b/arch/ia64/kernel/machine_kexec.c
@@ -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);
-}
-
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 49a6bd45957b..3d0b14afa232 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -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)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 3ae756c0db3d..3d1d808ea8a9 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -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();
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 22217ece26c8..44404e2307bb 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -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
diff --git a/arch/x86/xen/mmu_pv.c b/arch/x86/xen/mmu_pv.c
index 1d7a7213a310..cab28cf2cffb 100644
--- a/arch/x86/xen/mmu_pv.c
+++ b/arch/x86/xen/mmu_pv.c
@@ -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 */
diff --git a/include/linux/crash_core.h b/include/linux/crash_core.h
index 4090a42578a8..87506a02e914 100644
--- a/include/linux/crash_core.h
+++ b/include/linux/crash_core.h
@@ -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;
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 <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);
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index df1a9aa602a0..46ba853656f6 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -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);
--
2.10.2