x86/efistub: Revert to heap allocated boot_params for PE entrypoint

This is a partial revert of commit

8117961d98f ("x86/efi: Disregard setup header of loaded image")

which triggers boot issues on older Dell laptops. As it turns out,
switching back to a heap allocation for the struct boot_params
constructed by the EFI stub works around this, even though it is unclear
why.

Cc: Christian Heusel <[e-mail]>
Reported-by: <mavrix#[e-mail]>
Signed-off-by: Ard Biesheuvel <[e-mail]>

drivers/firmware/efi/libstub/x86-stub.c

···
 efi_status_t __efiapi efi_pe_entry(efi_handle_t handle,
 				   efi_system_table_t *sys_table_arg)
 {
-	static struct boot_params boot_params __page_aligned_bss;
-	struct setup_header *hdr = &boot_params.hdr;
 	efi_guid_t proto = LOADED_IMAGE_PROTOCOL_GUID;
+	struct boot_params *boot_params;
+	struct setup_header *hdr;
 	int options_size = 0;
 	efi_status_t status;
+	unsigned long alloc;
 	char *cmdline_ptr;
 
 	efi_system_table = sys_table_arg;
···
 		efi_exit(handle, status);
 	}
 
+	status = efi_allocate_pages(PARAM_SIZE, &alloc, ULONG_MAX);
+	if (status != EFI_SUCCESS)
+		efi_exit(handle, status);
+
+	boot_params = memset((void *)alloc, 0x0, PARAM_SIZE);
+	hdr	    = &boot_params->hdr;
+
 	/* Assign the setup_header fields that the kernel actually cares about */
 	hdr->root_flags	= 1;
 	hdr->vid_mode	= 0xffff;
···
 
 	/* Convert unicode cmdline to ascii */
 	cmdline_ptr = efi_convert_cmdline(image, &options_size);
-	if (!cmdline_ptr)
+	if (!cmdline_ptr) {
+		efi_free(PARAM_SIZE, alloc);
 		efi_exit(handle, EFI_OUT_OF_RESOURCES);
+	}
 
 	efi_set_u64_split((unsigned long)cmdline_ptr, &hdr->cmd_line_ptr,
-			  &boot_params.ext_cmd_line_ptr);
+			  &boot_params->ext_cmd_line_ptr);
 
-	efi_stub_entry(handle, sys_table_arg, &boot_params);
+	efi_stub_entry(handle, sys_table_arg, boot_params);
 	/* not reached */
 }