kexec_file: Fix kexec_file.c build error for riscv platform

When CONFIG_KEXEC_FILE is set for riscv platform, the compilation of
kernel/kexec_file.c generate build error:

kernel/kexec_file.c: In function 'crash_prepare_elf64_headers':
./arch/riscv/include/asm/page.h:110:71: error: request for member 'virt_addr' in something not a structure or union
  110 |  ((x) >= PAGE_OFFSET && (!IS_ENABLED(CONFIG_64BIT) || (x) < kernel_map.virt_addr))
      |                                                                       ^
./arch/riscv/include/asm/page.h:131:2: note: in expansion of macro 'is_linear_mapping'
  131 |  is_linear_mapping(_x) ?       \
      |  ^~~~~~~~~~~~~~~~~
./arch/riscv/include/asm/page.h:140:31: note: in expansion of macro '__va_to_pa_nodebug'
  140 | #define __phys_addr_symbol(x) __va_to_pa_nodebug(x)
      |                               ^~~~~~~~~~~~~~~~~~
./arch/riscv/include/asm/page.h:143:24: note: in expansion of macro '__phys_addr_symbol'
  143 | #define __pa_symbol(x) __phys_addr_symbol(RELOC_HIDE((unsigned long)(x), 0))
      |                        ^~~~~~~~~~~~~~~~~~
kernel/kexec_file.c:1327:36: note: in expansion of macro '__pa_symbol'
 1327 |   phdr->p_offset = phdr->p_paddr = __pa_symbol(_text);

This occurs is because the "kernel_map" referenced in macro
is_linear_mapping()  is suppose to be the one of struct kernel_mapping
defined in arch/riscv/mm/init.c, but the 2nd argument of
crash_prepare_elf64_header() has same symbol name, in expansion of macro
is_linear_mapping in function crash_prepare_elf64_header(), "kernel_map"
actually is the local variable.
Signed-off-by: Liao Chang <liaochang1@huawei.com>
Link: https://lore.kernel.org/r/20220408100914.150110-2-lizhengyu3@huawei.comSigned-off-by: Palmer Dabbelt <palmer@rivosinc.com>

include/linux/kexec.h

@@ -227,7 +227,7 @@ struct crash_mem {
 extern int crash_exclude_mem_range(struct crash_mem *mem,
 				   unsigned long long mstart,
 				   unsigned long long mend);
-extern int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
+extern int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 				       void **addr, unsigned long *sz);
 #endif /* CONFIG_KEXEC_FILE */
 

kernel/kexec_file.c

@@ -1260,7 +1260,7 @@ int crash_exclude_mem_range(struct crash_mem *mem,
 	return 0;
 }
 
-int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
+int crash_prepare_elf64_headers(struct crash_mem *mem, int need_kernel_map,
 			  void **addr, unsigned long *sz)
 {
 	Elf64_Ehdr *ehdr;
@@ -1324,7 +1324,7 @@ int crash_prepare_elf64_headers(struct crash_mem *mem, int kernel_map,
 	phdr++;
 
 	/* Prepare PT_LOAD type program header for kernel text region */
-	if (kernel_map) {
+	if (need_kernel_map) {
 		phdr->p_type = PT_LOAD;
 		phdr->p_flags = PF_R|PF_W|PF_X;
 		phdr->p_vaddr = (unsigned long) _text;