From d3c0c0c318d2e2b5a3d6276bb0fdd732170756d3 Mon Sep 17 00:00:00 2001 From: Hannah Williams Date: Fri, 27 Apr 2018 09:09:04 -0700 Subject: arch/x86: Relocate GDT in verstage, romstage, and postcar In each stage keep GDT in the code region. This accommodates platforms, such as glk, that are executing out of CAR. The gdt is small and loading it is trivial so just do it unconditionally instead of introducing another Kconfig. BUG=b:78656686 Change-Id: I01ded6e9b358b23e04d92bef5263bfe8c2a5ec5a Signed-off-by: Hannah Williams Signed-off-by: Aaron Durbin Reviewed-on: https://review.coreboot.org/25895 Tested-by: build bot (Jenkins) Reviewed-by: Furquan Shaikh Reviewed-by: Justin TerAvest --- src/arch/x86/Makefile.inc | 5 +++++ src/arch/x86/assembly_entry.S | 11 +++++++---- src/arch/x86/exit_car.S | 3 +++ src/arch/x86/gdt_init.S | 43 +++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 58 insertions(+), 4 deletions(-) create mode 100644 src/arch/x86/gdt_init.S (limited to 'src/arch/x86') diff --git a/src/arch/x86/Makefile.inc b/src/arch/x86/Makefile.inc index 0f4de166cb..df054f8748 100644 --- a/src/arch/x86/Makefile.inc +++ b/src/arch/x86/Makefile.inc @@ -171,6 +171,7 @@ endif # CONFIG_ARCH_BOOTBLOCK_X86_32 / CONFIG_ARCH_BOOTBLOCK_X86_64 ifeq ($(CONFIG_ARCH_VERSTAGE_X86_32)$(CONFIG_ARCH_VERSTAGE_X86_64),y) verstage-y += boot.c +verstage-$(CONFIG_VBOOT_SEPARATE_VERSTAGE) += gdt_init.S verstage-$(CONFIG_IDT_IN_EVERY_STAGE) += exception.c verstage-$(CONFIG_IDT_IN_EVERY_STAGE) += idt.S @@ -206,6 +207,9 @@ ifeq ($(CONFIG_ARCH_ROMSTAGE_X86_32)$(CONFIG_ARCH_ROMSTAGE_X86_64),y) romstage-$(CONFIG_HAVE_ACPI_RESUME) += acpi_s3.c romstage-y += boot.c +# gdt_init.S is included by entry32.inc when romstage is the first C +# environment. +romstage-$(CONFIG_C_ENVIRONMENT_BOOTBLOCK) += gdt_init.S romstage-y += cbmem.c romstage-y += cbfs_and_run.c romstage-$(CONFIG_ARCH_RAMSTAGE_X86_32) += cpu_common.c @@ -283,6 +287,7 @@ postcar-generic-ccopts += -D__POSTCAR__ postcar-$(CONFIG_HAVE_ACPI_RESUME) += acpi_s3.c postcar-y += boot.c +postcar-y += gdt_init.S postcar-y += cbfs_and_run.c postcar-y += cbmem.c postcar-y += cpu_common.c diff --git a/src/arch/x86/assembly_entry.S b/src/arch/x86/assembly_entry.S index a5399b74a5..02f492cfaa 100644 --- a/src/arch/x86/assembly_entry.S +++ b/src/arch/x86/assembly_entry.S @@ -20,15 +20,18 @@ /* * This path is for stages that are post bootblock when employing - * CONFIG_C_ENVIRONMENT_BOOTBLOCK. There's no need to re-load the gdt, - * etc as all those settings are cached within the processor. In order - * to continue with C code execution one needs to set stack pointer and - * clear CAR_GLOBAL variables that are stage specific. + * CONFIG_C_ENVIRONMENT_BOOTBLOCK. The gdt is reloaded to accommodate + * platforms that are executing out of CAR. In order to continue with + * C code execution one needs to set stack pointer and clear CAR_GLOBAL + * variables that are stage specific. */ .section ".text._start", "ax", @progbits .global _start _start: + /* Migrate GDT to this text segment */ + call gdt_init + /* reset stack pointer to CAR stack */ mov $_car_stack_end, %esp diff --git a/src/arch/x86/exit_car.S b/src/arch/x86/exit_car.S index 86d46ca95b..735399b8b1 100644 --- a/src/arch/x86/exit_car.S +++ b/src/arch/x86/exit_car.S @@ -30,6 +30,9 @@ _start: /* Assume stack alignment doesn't matter here as chipset_teardown_car is expected to be implemented in assembly. */ + /* Migrate GDT to this text segment */ + call gdt_init + /* chipset_teardown_car() is expected to disable cache-as-ram. */ call chipset_teardown_car diff --git a/src/arch/x86/gdt_init.S b/src/arch/x86/gdt_init.S new file mode 100644 index 0000000000..6aa2a79b48 --- /dev/null +++ b/src/arch/x86/gdt_init.S @@ -0,0 +1,43 @@ +/* + * This file is part of the coreboot project. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ +.code32 +.section ".text._gdt_", "ax", @progbits + + .globl gdt_init +gdt_init: + lgdt %cs:gdtptr + ret + +.previous + .align 4 +.globl gdtptr +gdt: +gdtptr: + .word gdt_end - gdt -1 /* compute the table limit */ + .long gdt /* we know the offset */ + .word 0 + + /* selgdt 0x08, flat code segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xcf, 0x00 /* G=1 and 0x0f, So we get 4Gbytes + for limit */ + + /* selgdt 0x10,flat data segment */ + .word 0xffff, 0x0000 + .byte 0x00, 0x93, 0xcf, 0x00 + + /* selgdt 0x18, flat code segment (64-bit) */ + .word 0xffff, 0x0000 + .byte 0x00, 0x9b, 0xaf, 0x00 + +gdt_end: -- cgit v1.2.3