diff options
| author | Matt Porter <mporter@konsulko.com> | 2015-05-05 15:00:23 -0400 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2015-05-28 08:18:23 -0400 |
| commit | f99993c10882f7dc8ec35993d5febe59aac01e6a (patch) | |
| tree | c91edb5481c62885690884d2197a3634e1171652 /arch/arm | |
| parent | c777efe3a1c3ea62123437a30468fa0b17a689b2 (diff) | |
common/cmd_boot: keep ARM v7M in thumb mode during do_go_exec()
On ARM v7M, the processor will return to ARM mode when executing
a blx instruction with bit 0 of the address == 0. Always set it
to 1 to stay in thumb mode.
Signed-off-by: Matt Porter <mporter@konsulko.com>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/lib/Makefile | 1 | ||||
| -rw-r--r-- | arch/arm/lib/cmd_boot.c | 44 |
2 files changed, 45 insertions, 0 deletions
diff --git a/arch/arm/lib/Makefile b/arch/arm/lib/Makefile index 0e1ad0e3dd..31a5c8d77f 100644 --- a/arch/arm/lib/Makefile +++ b/arch/arm/lib/Makefile @@ -26,6 +26,7 @@ ifndef CONFIG_SYS_GENERIC_BOARD obj-y += board.o endif +obj-$(CONFIG_CPU_V7M) += cmd_boot.o obj-$(CONFIG_OF_LIBFDT) += bootm-fdt.o obj-$(CONFIG_CMD_BOOTM) += bootm.o obj-$(CONFIG_SYS_L2_PL310) += cache-pl310.o diff --git a/arch/arm/lib/cmd_boot.c b/arch/arm/lib/cmd_boot.c new file mode 100644 index 0000000000..37bb6a567e --- /dev/null +++ b/arch/arm/lib/cmd_boot.c @@ -0,0 +1,44 @@ +/* + * (C) Copyright 2008-2011 + * Graeme Russ, <graeme.russ@gmail.com> + * + * (C) Copyright 2002 + * Daniel Engström, Omicron Ceti AB, <daniel@omicron.se> + * + * (C) Copyright 2002 + * Wolfgang Denk, DENX Software Engineering, <wd@denx.de> + * + * (C) Copyright 2002 + * Sysgo Real-Time Solutions, GmbH <www.elinos.com> + * Marius Groeger <mgroeger@sysgo.de> + * + * Copyright 2015 ATS Advanced Telematics Systems GmbH + * Copyright 2015 Konsulko Group, Matt Porter <mporter@konsulko.com> + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <command.h> + +DECLARE_GLOBAL_DATA_PTR; + +/* + * ARMv7M does not support ARM instruction mode. However, the + * interworking BLX and BX instructions do encode the ARM/Thumb + * field in bit 0. This means that when executing any Branch + * and eXchange instruction we must set bit 0 to one to guarantee + * that we keep the processor in Thumb instruction mode. From The + * ARMv7-M Instruction Set A4.1.1: + * "ARMv7-M only supports the Thumb instruction execution state, + * therefore the value of address bit [0] must be 1 in interworking + * instructions, otherwise a fault occurs." + */ +unsigned long do_go_exec(ulong (*entry)(int, char * const []), + int argc, char * const argv[]) +{ + ulong addr = (ulong)entry | 1; + entry = (void *)addr; + + return entry(argc, argv); +} |