From: Pingfan Liu <piliu@xxxxxxxxxx>
Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
Cc: Jiri Bohac <jbohac@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Philipp Rudo <prudo@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
To: kexec@xxxxxxxxxxxxxxxxxxx
---
include/linux/kexec.h | 1 +
init/main.c | 4 +++
kernel/crash_dump.c | 80 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 85 insertions(+)
diff --git a/include/linux/kexec.h b/include/linux/kexec.h
index 8227455192b7..95e19c814c93 100644
--- a/include/linux/kexec.h
+++ b/include/linux/kexec.h
@@ -410,6 +410,7 @@ extern bool kexec_in_progress;
int crash_shrink_memory(unsigned long new_size);
ssize_t crash_get_memory_size(void);
+void kdump_kernel_reuse_mem(void);
#ifndef arch_kexec_protect_crashkres
/*
diff --git a/init/main.c b/init/main.c
index e24b0780fdff..ed90097caaa8 100644
--- a/init/main.c
+++ b/init/main.c
@@ -99,6 +99,7 @@
#include <linux/init_syscalls.h>
#include <linux/stackdepot.h>
#include <linux/randomize_kstack.h>
+#include <linux/kexec.h>
#include <net/net_namespace.h>
#include <asm/io.h>
@@ -1068,6 +1069,9 @@ void start_kernel(void)
arch_post_acpi_subsys_init();
kcsan_init();
+ /* */
+ kdump_kernel_reuse_mem();
+
/* Do the rest non-__init'ed, we're now alive */
arch_call_rest_init();
diff --git a/kernel/crash_dump.c b/kernel/crash_dump.c
index 92da32275af5..4605005f9534 100644
--- a/kernel/crash_dump.c
+++ b/kernel/crash_dump.c
@@ -4,6 +4,7 @@
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/export.h>
+#include <linux/cc_platform.h>
/*
* stores the physical address of elf header of crash image
@@ -39,3 +40,82 @@ static int __init setup_elfcorehdr(char *arg)
return end > arg ? 0 : -EINVAL;
}
early_param("elfcorehdr", setup_elfcorehdr);
+
+u64 kdump_cma_pfn;
+u64 kdump_cma_pg_cnt;
+u64 kdump_cma_pg_paddr;
+
+/* In old kernel, wreck should correspond to pfn */
+static void check_poison_page(struct page *wreck, int cnt, unsigned long pfn)
+{
+ int i = 0;
+ int order;
+ /* Info copied from old kernel */
+ struct page *check = wreck;
+ struct page *p;
+
+ /*
+ * Strictly check, but there is still a rare case, where both _refcnt and
+ * _mapcount are forged by some wrong code
+ */
+ for (; i < cnt; i += 1 << order) {
+ order = folio_order((struct folio *)check);
+ if (PageBuddy(check)) {
+ if (page_count(check) != 0 || total_mapcount(check) != 0)
+ goto fail;
+ if (check->index != 0)
+ goto fail;
+ if (check->lru.next != LIST_POISON1 ||
+ check->lru.prev != LIST_POISON2)
+ goto fail;
+
+ } else if (folio_test_anon((struct folio *)check)) {
+ /* check PAGE_MAPPING_ANON bit in mapping */
+ if (!((unsigned long)check->mapping & PAGE_MAPPING_ANON))
+ goto fail;
+ if (page_count(check) == 0)
+ goto fail;
+ if (total_mapcount(check) != page_count(check))
+ goto fail;
+ } else {
+ goto fail;
+ }
+
+ p = pfn_to_page(pfn);
+ for (int j = 0; j < 1 << order; j++)
+ ClearPageReserved(p + j);
+ __free_pages(p, order);
+
+fail:
+ check += 1 << order;
+ pfn += 1 << order;
+ }
+}
+
+void kdump_kernel_reuse_mem(void)
+{
+ u64 size;
+ struct page *wreck;
+ struct kvec kvec;
+ struct iov_iter iter;
+ char *buf;
+
+ if (!is_kdump_kernel())
+ return;
+
+ if (!kdump_cma_pfn || !kdump_cma_pg_cnt || !kdump_cma_pg_paddr)
+ return;
+
+ size = kdump_cma_pg_cnt * sizeof(struct page);
+ /* copy the wreck's page[] */
+ buf = kmalloc(size, GFP_KERNEL);
+ if (!buf)
+ return;
+ wreck = (struct page *)buf;
+ kvec.iov_base = buf;
+ kvec.iov_len = size;
+ iov_iter_kvec(&iter, ITER_DEST, &kvec, 1, size);
+ read_from_oldmem(&iter, size, &kdump_cma_pg_paddr,
+ cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
+ check_poison_page(wreck, kdump_cma_pg_cnt, kdump_cma_pfn);
+}
--
2.31.1
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