efi/x86: Avoid using code32_start
code32_start is meant for 16-bit real-mode bootloaders to inform the
kernel where the 32-bit protected mode code starts. Nothing in the
protected mode kernel except the EFI stub uses it.
efi_main() currently returns boot_params, with code32_start set inside it
to tell efi_stub_entry() where startup_32 is located. Since it was invoked
by efi_stub_entry() in the first place, boot_params is already known.
Return the address of startup_32 instead.
This will allow a 64-bit kernel to live above 4Gb, for example, and it's
cleaner as well.
Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200301230436.2246909-5-nivedita@alum.mit.edu
Link: https://lore.kernel.org/r/20200308080859.21568-13-ardb@kernel.org
diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c
index 9db9883..7f3e97c 100644
--- a/drivers/firmware/efi/libstub/x86-stub.c
+++ b/drivers/firmware/efi/libstub/x86-stub.c
@@ -703,10 +703,11 @@ static efi_status_t exit_boot(struct boot_params *boot_params, void *handle)
}
/*
- * On success we return a pointer to a boot_params structure, and NULL
- * on failure.
+ * On success, we return the address of startup_32, which has potentially been
+ * relocated by efi_relocate_kernel.
+ * On failure, we exit to the firmware via efi_exit instead of returning.
*/
-struct boot_params *efi_main(efi_handle_t handle,
+unsigned long efi_main(efi_handle_t handle,
efi_system_table_t *sys_table_arg,
struct boot_params *boot_params)
{
@@ -736,7 +737,6 @@ struct boot_params *efi_main(efi_handle_t handle,
goto fail;
}
}
- hdr->code32_start = (u32)bzimage_addr;
/*
* efi_pe_entry() may have been called before efi_main(), in which
@@ -799,7 +799,7 @@ struct boot_params *efi_main(efi_handle_t handle,
goto fail;
}
- return boot_params;
+ return bzimage_addr;
fail:
efi_printk("efi_main() failed!\n");