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-rw-r--r--include/linux/kexec.h2
-rw-r--r--kernel/kexec.c59
-rw-r--r--kernel/ksysfs.c21
3 files changed, 82 insertions, 0 deletions
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index adc34f2..c356b69 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -206,6 +206,8 @@ extern size_t vmcoreinfo_max_size;
int __init parse_crashkernel(char *cmdline, unsigned long long system_ram,
unsigned long long *crash_size, unsigned long long *crash_base);
+int crash_shrink_memory(unsigned long new_size);
+size_t crash_get_memory_size(void);
#else /* !CONFIG_KEXEC */
struct pt_regs;
diff --git a/kernel/kexec.c b/kernel/kexec.c
index f336e21..433e9fc 100644
--- a/kernel/kexec.c
+++ b/kernel/kexec.c
@@ -31,6 +31,7 @@
#include <linux/cpu.h>
#include <linux/console.h>
#include <linux/vmalloc.h>
+#include <linux/swap.h>
#include <asm/page.h>
#include <asm/uaccess.h>
@@ -1082,6 +1083,64 @@ void crash_kexec(struct pt_regs *regs)
}
}
+size_t crash_get_memory_size(void)
+{
+ size_t size;
+ mutex_lock(&kexec_mutex);
+ size = crashk_res.end - crashk_res.start + 1;
+ mutex_unlock(&kexec_mutex);
+ return size;
+}
+
+static void free_reserved_phys_range(unsigned long begin, unsigned long end)
+{
+ unsigned long addr;
+
+ for (addr = begin; addr < end; addr += PAGE_SIZE) {
+ ClearPageReserved(pfn_to_page(addr >> PAGE_SHIFT));
+ init_page_count(pfn_to_page(addr >> PAGE_SHIFT));
+ free_page((unsigned long)__va(addr));
+ totalram_pages++;
+ }
+}
+
+int crash_shrink_memory(unsigned long new_size)
+{
+ int ret = 0;
+ unsigned long start, end;
+
+ mutex_lock(&kexec_mutex);
+
+ if (kexec_crash_image) {
+ ret = -ENOENT;
+ goto unlock;
+ }
+ start = crashk_res.start;
+ end = crashk_res.end;
+
+ if (new_size >= end - start + 1) {
+ ret = -EINVAL;
+ if (new_size == end - start + 1)
+ ret = 0;
+ goto unlock;
+ }
+
+ start = roundup(start, PAGE_SIZE);
+ end = roundup(start + new_size, PAGE_SIZE);
+
+ free_reserved_phys_range(end, crashk_res.end);
+
+ if (start == end) {
+ crashk_res.end = end;
+ release_resource(&crashk_res);
+ } else
+ crashk_res.end = end - 1;
+
+unlock:
+ mutex_unlock(&kexec_mutex);
+ return ret;
+}
+
static u32 *append_elf_note(u32 *buf, char *name, unsigned type, void *data,
size_t data_len)
{
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 528dd78..3feaf5a 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -100,6 +100,26 @@ static ssize_t kexec_crash_loaded_show(struct kobject *kobj,
}
KERNEL_ATTR_RO(kexec_crash_loaded);
+static ssize_t kexec_crash_size_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%zu\n", crash_get_memory_size());
+}
+static ssize_t kexec_crash_size_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ unsigned long cnt;
+ int ret;
+
+ if (strict_strtoul(buf, 0, &cnt))
+ return -EINVAL;
+
+ ret = crash_shrink_memory(cnt);
+ return ret < 0 ? ret : count;
+}
+KERNEL_ATTR_RW(kexec_crash_size);
+
static ssize_t vmcoreinfo_show(struct kobject *kobj,
struct kobj_attribute *attr, char *buf)
{
@@ -147,6 +167,7 @@ static struct attribute * kernel_attrs[] = {
#ifdef CONFIG_KEXEC
&kexec_loaded_attr.attr,
&kexec_crash_loaded_attr.attr,
+ &kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
NULL
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