From abf44e17e8d955caa55bb6db096637be2b555f53 Mon Sep 17 00:00:00 2001 From: andrew Date: Mon, 27 Aug 2018 11:14:49 +0000 Subject: [PATCH] Ensure we have a large enough stack for the lua loader Lua has a few places where it allocates a large buffer on the stack. This is normally fine, except there are a few places where there can be multiple frames with this buffer. This can cause a stack overflow on some arm64 SoCs. Fix this by allocating our own stack in loader.efi large enough for these objects. The required size has been found by tracing how the stack pointer changes in a virtual machine and found to be no larger than 50kB. A larger stack is allocated to reduce the likelihood of overflow from future changes. Reviewed by: kevans Approved by: re (kib) Differential Revision: https://reviews.freebsd.org/D16886 --- stand/efi/boot1/Makefile | 1 + stand/efi/loader/arch/arm64/start.S | 17 +++++++++++++++++ 2 files changed, 18 insertions(+) diff --git a/stand/efi/boot1/Makefile b/stand/efi/boot1/Makefile index 57610292bd83..88bbb312970c 100644 --- a/stand/efi/boot1/Makefile +++ b/stand/efi/boot1/Makefile @@ -6,6 +6,7 @@ PROG= boot1.sym INTERNALPROG= WARNS?= 6 +CFLAGS+= -DEFI_BOOT1 # We implement a slightly non-standard %S in that it always takes a # CHAR16 that's common in UEFI-land instead of a wchar_t. This only # seems to matter on arm64 where wchar_t defaults to an int instead diff --git a/stand/efi/loader/arch/arm64/start.S b/stand/efi/loader/arch/arm64/start.S index b58c2c50be9f..bddc2d088a64 100644 --- a/stand/efi/loader/arch/arm64/start.S +++ b/stand/efi/loader/arch/arm64/start.S @@ -160,6 +160,23 @@ _start: ldp x0, x1, [sp], #16 +#ifndef EFI_BOOT1 + /* + * Load the stack to use. The default stack may be too small for + * the lua loader. + */ + adr x2, initstack_end + mov sp, x2 +#endif + bl efi_main 1: b 1b + +#ifndef EFI_BOOT1 +.bss + .align 4 +initstack: + .space (64 * 1024) +initstack_end: +#endif