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Diffstat (limited to 'nuttx/arch/arm/src/armv6-m/exc_return.h')
| -rw-r--r-- | nuttx/arch/arm/src/armv6-m/exc_return.h | 120 |
1 files changed, 120 insertions, 0 deletions
diff --git a/nuttx/arch/arm/src/armv6-m/exc_return.h b/nuttx/arch/arm/src/armv6-m/exc_return.h new file mode 100644 index 000000000..e779df505 --- /dev/null +++ b/nuttx/arch/arm/src/armv6-m/exc_return.h @@ -0,0 +1,120 @@ +/************************************************************************************ + * arch/arm/src/armv6-m/exc_return.h + * + * Copyright (C) 2013 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <gnutt@nuttx.org> + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in + * the documentation and/or other materials provided with the + * distribution. + * 3. Neither the name NuttX nor the names of its contributors may be + * used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, + * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS + * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED + * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN + * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE + * POSSIBILITY OF SUCH DAMAGE. + * + ************************************************************************************/ + +#ifndef __ARCH_ARM_SRC_ARMV6_M_EXC_RETURN_H +#define __ARCH_ARM_SRC_ARMV6_M_EXC_RETURN_H + +/************************************************************************************ + * Included Files + ************************************************************************************/ + +#include <nuttx/config.h> + +/************************************************************************************ + * Pre-processor Definitions + ************************************************************************************/ + +/* The processor saves an EXC_RETURN value to the LR on exception entry. The + * exception mechanism relies on this value to detect when the processor has + * completed an exception handler. + * + * Bits [31:28] of an EXC_RETURN value are always 1. When the processor loads a + * value matching this pattern to the PC it detects that the operation is a not + * a normal branch operation and instead, that the exception is complete. + * Therefore, it starts the exception return sequence. + * + * Bits[4:0] of the EXC_RETURN value indicate the required return stack and eventual + * processor mode. The remaining bits of the EXC_RETURN value should be set to 1. + */ + +/* EXC_RETURN_BASE: Bits that are always set in an EXC_RETURN value. */ + +#define EXC_RETURN_BASE 0xffffffe1 + +/* EXC_RETURN_PROCESS_STACK: The exception saved (and will restore) the hardware + * context using the process stack pointer (if not set, the context was saved + * using the main stack pointer) + */ + +#define EXC_RETURN_PROCESS_BITNO (2) +#define EXC_RETURN_PROCESS_STACK (1 << EXC_RETURN_PROCESS_BITNO) + +/* EXC_RETURN_THREAD_MODE: The exception will return to thread mode (if not set, + * return stays in handler mode) + */ + +#define EXC_RETURN_THREAD_BITNO (3) +#define EXC_RETURN_THREAD_MODE (1 << EXC_RETURN_THREAD_BITNO) + +/* EXC_RETURN_STD_CONTEXT: The state saved on the stack does not include the + * volatile FP registers and FPSCR. If this bit is clear, the state does include + * these registers. + */ + +#define EXC_RETURN_STD_BITNO (4) +#define EXC_RETURN_STD_CONTEXT (1 << EXC_RETURN_STD_BITNO) + +/* EXC_RETURN_HANDLER: Return to handler mode. Exception return gets state from + * the main stack. Execution uses MSP after return. + */ + +#define EXC_RETURN_HANDLER 0xfffffff1 + +/* EXC_RETURN_PRIVTHR: Return to privileged thread mode. Exception return gets + * state from the main stack. Execution uses MSP after return. + */ + +#define EXC_RETURN_PRIVTHR 0xfffffff9 + +/* EXC_RETURN_UNPRIVTHR: Return to unprivileged thread mode. Exception return gets + * state from the process stack. Execution uses PSP after return. + */ + +#define EXC_RETURN_UNPRIVTHR 0xfffffffd + +/* In the kernel build is not selected, then all threads run in privileged thread + * mode. + */ + +#ifdef CONFIG_NUTTX_KERNEL +# define EXC_RETURN 0xfffffff9 +#endif + +/************************Th************************************************************ + * Inline Functions + ************************************************************************************/ + +#endif /* __ARCH_ARM_SRC_ARMV6_M_EXC_RETURN_H */ + |