kernel/crash: handle multi-page vmcoreinfo in crash kernel copy

kimage_crash_copy_vmcoreinfo() currently assumes vmcoreinfo fits in a
single page.  This breaks if VMCOREINFO_BYTES exceeds PAGE_SIZE.

Allocate the required order of control pages and vmap all pages needed to
safely copy vmcoreinfo into the crash kernel image.

Link: https://lkml.kernel.org/r/20251216132801.807260-3-pnina.feder@mobileye.com
Signed-off-by: Pnina Feder <pnina.feder@mobileye.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/kernel/crash_core.c b/kernel/crash_core.c
index 99dac1aa972af0db10e90627815632d43f563d06..3952b3e102e0d2d3fb6d403666af7400e0a4f9ff 100644 (file)
--- a/kernel/crash_core.c
+++ b/kernel/crash_core.c
@@ -44,9 +44,15 @@ note_buf_t __percpu *crash_notes;
 
 int kimage_crash_copy_vmcoreinfo(struct kimage *image)
 {
-       struct page *vmcoreinfo_page;
+       struct page *vmcoreinfo_base;
+       struct page *vmcoreinfo_pages[DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE)];
+       unsigned int order, nr_pages;
+       int i;
        void *safecopy;
 
+       nr_pages = DIV_ROUND_UP(VMCOREINFO_BYTES, PAGE_SIZE);
+       order = get_order(VMCOREINFO_BYTES);
+
        if (!IS_ENABLED(CONFIG_CRASH_DUMP))
                return 0;
        if (image->type != KEXEC_TYPE_CRASH)
@@ -61,12 +67,15 @@ int kimage_crash_copy_vmcoreinfo(struct kimage *image)
         * happens to generate vmcoreinfo note, hereby we rely on
         * vmap for this purpose.
         */
-       vmcoreinfo_page = kimage_alloc_control_pages(image, 0);
-       if (!vmcoreinfo_page) {
+       vmcoreinfo_base = kimage_alloc_control_pages(image, order);
+       if (!vmcoreinfo_base) {
                pr_warn("Could not allocate vmcoreinfo buffer\n");
                return -ENOMEM;
        }
-       safecopy = vmap(&vmcoreinfo_page, 1, VM_MAP, PAGE_KERNEL);
+       for (i = 0; i < nr_pages; i++)
+               vmcoreinfo_pages[i] = vmcoreinfo_base + i;
+
+       safecopy = vmap(vmcoreinfo_pages, nr_pages, VM_MAP, PAGE_KERNEL);
        if (!safecopy) {
                pr_warn("Could not vmap vmcoreinfo buffer\n");
                return -ENOMEM;