add dts config

hc

2023-12-06 08f87f769b595151be1afeff53e144f543faa614

 kernel/arch/x86/kernel/crash_dump_32.c
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@@ -13,8 +13,6 @@
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 #include <linux/uaccess.h>
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-static void *kdump_buf_page;
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-
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 static inline bool is_crashed_pfn_valid(unsigned long pfn)
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 {
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 #ifndef CONFIG_X86_PAE
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@@ -41,15 +39,11 @@
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  * @userbuf: if set, @buf is in user address space, use copy_to_user(),
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  *	otherwise @buf is in kernel address space, use memcpy().
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  *
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- * Copy a page from "oldmem". For this page, there is no pte mapped
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- * in the current kernel. We stitch up a pte, similar to kmap_atomic.
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- *
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- * Calling copy_to_user() in atomic context is not desirable. Hence first
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- * copying the data to a pre-allocated kernel page and then copying to user
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- * space in non-atomic context.
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+ * Copy a page from "oldmem". For this page, there might be no pte mapped
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+ * in the current kernel.
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  */
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-ssize_t copy_oldmem_page(unsigned long pfn, char *buf,
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-                               size_t csize, unsigned long offset, int userbuf)
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+ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
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+			 unsigned long offset, int userbuf)
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 {
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 	void  *vaddr;
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@@ -59,38 +53,16 @@
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 	if (!is_crashed_pfn_valid(pfn))
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 		return -EFAULT;
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-	vaddr = kmap_atomic_pfn(pfn);
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+	vaddr = kmap_local_pfn(pfn);
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 	if (!userbuf) {
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-		memcpy(buf, (vaddr + offset), csize);
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-		kunmap_atomic(vaddr);
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+		memcpy(buf, vaddr + offset, csize);
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 	} else {
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-		if (!kdump_buf_page) {
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-			printk(KERN_WARNING "Kdump: Kdump buffer page not"
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-				" allocated\n");
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-			kunmap_atomic(vaddr);
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-			return -EFAULT;
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-		}
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-		copy_page(kdump_buf_page, vaddr);
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-		kunmap_atomic(vaddr);
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-		if (copy_to_user(buf, (kdump_buf_page + offset), csize))
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-			return -EFAULT;
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+		if (copy_to_user(buf, vaddr + offset, csize))
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+			csize = -EFAULT;
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 	}
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+
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+	kunmap_local(vaddr);
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 	return csize;
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 }
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-
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-static int __init kdump_buf_page_init(void)
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-{
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-	int ret = 0;
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-
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-	kdump_buf_page = kmalloc(PAGE_SIZE, GFP_KERNEL);
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-	if (!kdump_buf_page) {
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-		printk(KERN_WARNING "Kdump: Failed to allocate kdump buffer"
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-			 " page\n");
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-		ret = -ENOMEM;
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-	}
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-
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-	return ret;
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-}
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-arch_initcall(kdump_buf_page_init);