kexec_file: Allow arch-specific memory walking for kexec_add_buffer

Allow architectures to specify a different memory walking function for
kexec_add_buffer. x86 uses iomem to track reserved memory ranges, but
PowerPC uses the memblock subsystem.
Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Acked-by: Dave Young <dyoung@redhat.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

include/linux/kexec.h

@@ -148,7 +148,34 @@ struct kexec_file_ops {
 	kexec_verify_sig_t *verify_sig;
 #endif
 };
-#endif
+
+/**
+ * struct kexec_buf - parameters for finding a place for a buffer in memory
+ * @image:	kexec image in which memory to search.
+ * @buffer:	Contents which will be copied to the allocated memory.
+ * @bufsz:	Size of @buffer.
+ * @mem:	On return will have address of the buffer in memory.
+ * @memsz:	Size for the buffer in memory.
+ * @buf_align:	Minimum alignment needed.
+ * @buf_min:	The buffer can't be placed below this address.
+ * @buf_max:	The buffer can't be placed above this address.
+ * @top_down:	Allocate from top of memory.
+ */
+struct kexec_buf {
+	struct kimage *image;
+	char *buffer;
+	unsigned long bufsz;
+	unsigned long mem;
+	unsigned long memsz;
+	unsigned long buf_align;
+	unsigned long buf_min;
+	unsigned long buf_max;
+	bool top_down;
+};
+
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *));
+#endif /* CONFIG_KEXEC_FILE */
 
 struct kimage {
 	kimage_entry_t head;

kernel/kexec_file.c

@@ -428,6 +428,27 @@ static int locate_mem_hole_callback(u64 start, u64 end, void *arg)
 	return locate_mem_hole_bottom_up(start, end, kbuf);
 }
 
+/**
+ * arch_kexec_walk_mem - call func(data) on free memory regions
+ * @kbuf:	Context info for the search. Also passed to @func.
+ * @func:	Function to call for each memory region.
+ *
+ * Return: The memory walk will stop when func returns a non-zero value
+ * and that value will be returned. If all free regions are visited without
+ * func returning non-zero, then zero will be returned.
+ */
+int __weak arch_kexec_walk_mem(struct kexec_buf *kbuf,
+			       int (*func)(u64, u64, void *))
+{
+	if (kbuf->image->type == KEXEC_TYPE_CRASH)
+		return walk_iomem_res_desc(crashk_res.desc,
+					   IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
+					   crashk_res.start, crashk_res.end,
+					   kbuf, func);
+	else
+		return walk_system_ram_res(0, ULONG_MAX, kbuf, func);
+}
+
 /*
  * Helper function for placing a buffer in a kexec segment. This assumes
  * that kexec_mutex is held.
@@ -474,14 +495,7 @@ int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz,
 	kbuf->top_down = top_down;
 
 	/* Walk the RAM ranges and allocate a suitable range for the buffer */
-	if (image->type == KEXEC_TYPE_CRASH)
-		ret = walk_iomem_res_desc(crashk_res.desc,
-				IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY,
-				crashk_res.start, crashk_res.end, kbuf,
-				locate_mem_hole_callback);
-	else
-		ret = walk_system_ram_res(0, -1, kbuf,
-					  locate_mem_hole_callback);
+	ret = arch_kexec_walk_mem(kbuf, locate_mem_hole_callback);
 	if (ret != 1) {
 		/* A suitable memory range could not be found for buffer */
 		return -EADDRNOTAVAIL;

kernel/kexec_internal.h

@@ -20,22 +20,6 @@ struct kexec_sha_region {
 	unsigned long len;
 };
 
-/*
- * Keeps track of buffer parameters as provided by caller for requesting
- * memory placement of buffer.
- */
-struct kexec_buf {
-	struct kimage *image;
-	char *buffer;
-	unsigned long bufsz;
-	unsigned long mem;
-	unsigned long memsz;
-	unsigned long buf_align;
-	unsigned long buf_min;
-	unsigned long buf_max;
-	bool top_down;		/* allocate from top of memory hole */
-};
-
 void kimage_file_post_load_cleanup(struct kimage *image);
 #else /* CONFIG_KEXEC_FILE */
 static inline void kimage_file_post_load_cleanup(struct kimage *image) { }