powerpc/kexec_file: Avoid stomping memory used by special regions

crashkernel region could have an overlap with special memory regions
like OPAL, RTAS, TCE table & such. These regions are referred to as
excluded memory ranges. Setup these ranges during image probe in order
to avoid them while finding the buffer for different kdump segments.
Override arch_kexec_locate_mem_hole() to locate a memory hole taking
these ranges into account.

Signed-off-by: Hari Bathini <hbathini@linux.ibm.com>
Reviewed-by: Thiago Jung Bauermann <bauerman@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/159602281047.575379.6636807148335160795.stgit@hbathini

arch/powerpc/include/asm/kexec.h

@@ -100,14 +100,16 @@ void relocate_new_kernel(unsigned long indirection_page, unsigned long reboot_co
 #ifdef CONFIG_KEXEC_FILE
 extern const struct kexec_file_ops kexec_elf64_ops;
 
-#ifdef CONFIG_IMA_KEXEC
 #define ARCH_HAS_KIMAGE_ARCH
 
 struct kimage_arch {
+	struct crash_mem *exclude_ranges;
+
+#ifdef CONFIG_IMA_KEXEC
 	phys_addr_t ima_buffer_addr;
 	size_t ima_buffer_size;
-};
 #endif
+};
 
 int setup_purgatory(struct kimage *image, const void *slave_code,
 		    const void *fdt, unsigned long kernel_load_addr,
@@ -125,6 +127,7 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
 			unsigned long initrd_load_addr,
 			unsigned long initrd_len, const char *cmdline);
 #endif /* CONFIG_PPC64 */
+
 #endif /* CONFIG_KEXEC_FILE */
 
 #else /* !CONFIG_KEXEC_CORE */

arch/powerpc/include/asm/kexec_ranges.h

@@ -7,5 +7,19 @@
 void sort_memory_ranges(struct crash_mem *mrngs, bool merge);
 struct crash_mem *realloc_mem_ranges(struct crash_mem **mem_ranges);
 int add_mem_range(struct crash_mem **mem_ranges, u64 base, u64 size);
+int add_tce_mem_ranges(struct crash_mem **mem_ranges);
+int add_initrd_mem_range(struct crash_mem **mem_ranges);
+#ifdef CONFIG_PPC_BOOK3S_64
+int add_htab_mem_range(struct crash_mem **mem_ranges);
+#else
+static inline int add_htab_mem_range(struct crash_mem **mem_ranges)
+{
+	return 0;
+}
+#endif
+int add_kernel_mem_range(struct crash_mem **mem_ranges);
+int add_rtas_mem_range(struct crash_mem **mem_ranges);
+int add_opal_mem_range(struct crash_mem **mem_ranges);
+int add_reserved_mem_ranges(struct crash_mem **mem_ranges);
 
 #endif /* _ASM_POWERPC_KEXEC_RANGES_H */

arch/powerpc/kexec/elf_64.c

@@ -46,6 +46,14 @@ static void *elf64_load(struct kimage *image, char *kernel_buf,
 	if (ret)
 		goto out;
 
+	if (image->type == KEXEC_TYPE_CRASH) {
+		/* min & max buffer values for kdump case */
+		kbuf.buf_min = pbuf.buf_min = crashk_res.start;
+		kbuf.buf_max = pbuf.buf_max =
+				((crashk_res.end < ppc64_rma_size) ?
+				 crashk_res.end : (ppc64_rma_size - 1));
+	}
+
 	ret = kexec_elf_load(image, &ehdr, &elf_info, &kbuf, &kernel_load_addr);
 	if (ret)
 		goto out;