From 3b8f44fc0810d51b58837cf7fdba3f72f8cffcdc Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Sun, 16 Feb 2020 00:03:25 +0100 Subject: [PATCH] efi/libstub/x86: Use Exit() boot service to exit the stub on errors Currently, we either return with an error [from efi_pe_entry()] or enter a deadloop [in efi_main()] if any fatal errors occur during execution of the EFI stub. Let's switch to calling the Exit() EFI boot service instead in both cases, so that we a) can get rid of the deadloop, and simply return to the boot manager if any errors occur during execution of the stub, including during the call to ExitBootServices(), b) can also return cleanly from efi_pe_entry() or efi_main() in mixed mode, once we introduce support for LoadImage/StartImage based mixed mode in the next patch. Note that on systems running downstream GRUBs [which do not use LoadImage or StartImage to boot the kernel, and instead, pass their own image handle as the loaded image handle], calling Exit() will exit from GRUB rather than from the kernel, but this is a tolerable side effect. Signed-off-by: Ard Biesheuvel --- arch/x86/include/asm/efi.h | 8 ++++++++ drivers/firmware/efi/libstub/efistub.h | 5 ++++- drivers/firmware/efi/libstub/x86-stub.c | 20 +++++++++++++------- 3 files changed, 25 insertions(+), 8 deletions(-) diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h index 0de57151c732..cdcf48d52a12 100644 --- a/arch/x86/include/asm/efi.h +++ b/arch/x86/include/asm/efi.h @@ -270,6 +270,11 @@ static inline void *efi64_zero_upper(void *p) return p; } +static inline u32 efi64_convert_status(efi_status_t status) +{ + return (u32)(status | (u64)status >> 32); +} + #define __efi64_argmap_free_pages(addr, size) \ ((addr), 0, (size)) @@ -288,6 +293,9 @@ static inline void *efi64_zero_upper(void *p) #define __efi64_argmap_locate_device_path(protocol, path, handle) \ ((protocol), (path), efi64_zero_upper(handle)) +#define __efi64_argmap_exit(handle, status, size, data) \ + ((handle), efi64_convert_status(status), (size), (data)) + /* PCI I/O */ #define __efi64_argmap_get_location(protocol, seg, bus, dev, func) \ ((protocol), efi64_zero_upper(seg), efi64_zero_upper(bus), \ diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index 6960e730f990..cc90a748bcf0 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -144,7 +144,10 @@ union efi_boot_services { void *); void *load_image; void *start_image; - void *exit; + efi_status_t __noreturn (__efiapi *exit)(efi_handle_t, + efi_status_t, + unsigned long, + efi_char16_t *); void *unload_image; efi_status_t (__efiapi *exit_boot_services)(efi_handle_t, unsigned long); diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index ce0c3caa3087..cec6baa14d5c 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -340,6 +340,13 @@ static void setup_graphics(struct boot_params *boot_params) } } + +static void __noreturn efi_exit(efi_handle_t handle, efi_status_t status) +{ + efi_bs_call(exit, handle, status, 0, NULL); + unreachable(); +} + void startup_32(struct boot_params *boot_params); void __noreturn efi_stub_entry(efi_handle_t handle, @@ -369,12 +376,12 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, /* Check if we were booted by the EFI firmware */ if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) - return EFI_INVALID_PARAMETER; + efi_exit(handle, EFI_INVALID_PARAMETER); status = efi_bs_call(handle_protocol, handle, &proto, (void *)&image); if (status != EFI_SUCCESS) { efi_printk("Failed to get handle for LOADED_IMAGE_PROTOCOL\n"); - return status; + efi_exit(handle, status); } hdr = &((struct boot_params *)efi_table_attr(image, image_base))->hdr; @@ -384,7 +391,7 @@ efi_status_t __efiapi efi_pe_entry(efi_handle_t handle, above4g ? ULONG_MAX : UINT_MAX); if (status != EFI_SUCCESS) { efi_printk("Failed to allocate lowmem for boot params\n"); - return status; + efi_exit(handle, status); } memset(boot_params, 0x0, 0x4000); @@ -442,7 +449,7 @@ fail2: fail: efi_free(0x4000, (unsigned long)boot_params); - return status; + efi_exit(handle, status); } static void add_e820ext(struct boot_params *params, @@ -709,7 +716,7 @@ struct boot_params *efi_main(efi_handle_t handle, /* Check if we were booted by the EFI firmware */ if (sys_table->hdr.signature != EFI_SYSTEM_TABLE_SIGNATURE) - goto fail; + efi_exit(handle, EFI_INVALID_PARAMETER); /* * If the kernel isn't already loaded at the preferred load @@ -793,6 +800,5 @@ struct boot_params *efi_main(efi_handle_t handle, fail: efi_printk("efi_main() failed!\n"); - for (;;) - asm("hlt"); + efi_exit(handle, status); }