diff options
Diffstat (limited to 'nuttx/arch/arm/src/sam3u/sam3u_vectors.S')
| -rw-r--r-- | nuttx/arch/arm/src/sam3u/sam3u_vectors.S | 71 |
1 files changed, 66 insertions, 5 deletions
diff --git a/nuttx/arch/arm/src/sam3u/sam3u_vectors.S b/nuttx/arch/arm/src/sam3u/sam3u_vectors.S index 53e2f636c..ec0287e34 100644 --- a/nuttx/arch/arm/src/sam3u/sam3u_vectors.S +++ b/nuttx/arch/arm/src/sam3u/sam3u_vectors.S @@ -39,6 +39,7 @@ ************************************************************************************************/ #include <nuttx/config.h> + #include <arch/irq.h> /************************************************************************************************ @@ -240,13 +241,18 @@ sam3u_common: */ adds r2, r14, #3 /* If R14=0xfffffffd, then r2 == 0 */ - ite ne /* Next two instructions are condition */ + ite ne /* Next two instructions are conditional */ mrsne r1, msp /* R1=The main stack pointer */ mrseq r1, psp /* R1=The process stack pointer */ #else mrs r1, msp /* R1=The main stack pointer */ #endif + /* r1 holds the value of the stack pointer AFTER the excption handling logic + * pushed the various registers onto the stack. Get r2 = the value of the + * stack pointer BEFORE the interrupt modified it. + */ + mov r2, r1 /* R2=Copy of the main/process stack pointer */ add r2, #HW_XCPT_SIZE /* R2=MSP/PSP before the interrupt was taken */ #ifdef CONFIG_ARMV7M_USEBASEPRI @@ -254,6 +260,22 @@ sam3u_common: #else mrs r3, primask /* R3=Current PRIMASK setting */ #endif + +#ifdef CONFIG_ARCH_FPU + /* Skip over the block of memory reserved for floating pointer register save. + * Lazy FPU register saving is used. FPU registers will be saved in this + * block only if a context switch occurs (this means, of course, that the FPU + * cannot be used in interrupt processing). + */ + + sub r1, #(4*SW_FPU_REGS) +#endif + + /* Save the the remaining registers on the stack after the registers pushed + * by the exception handling logic. r2=SP and r3=primask or basepri, r4-r11, + * r14=register values. + */ + #ifdef CONFIG_NUTTX_KERNEL stmdb r1!, {r2-r11,r14} /* Save the remaining registers plus the SP value */ #else @@ -290,17 +312,36 @@ sam3u_common: cmp r0, r1 /* Context switch? */ beq 1f /* Branch if no context switch */ + /* We are returning with a pending context switch. + * + * If the FPU is enabled, then we will need to restore FPU registers. + * This is not done in normal interrupt save/restore because the cost + * is prohibitive. This is only done when switching contexts. A + * consequence of this is that floating point operations may not be + * performed in interrupt handling logic. + * + * Here: + * r0 = Address of the register save area + + * NOTE: It is a requirement that up_restorefpu() preserve the value of + * r0! + */ + +#ifdef CONFIG_ARCH_FPU + bl up_restorefpu /* Restore the FPU registers */ +#endif + /* We are returning with a pending context switch. This case is different * because in this case, the register save structure does not lie on the * stack but, rather, are within a TCB structure. We'll have to copy some * values to the stack. */ - add r1, r0, #SW_XCPT_SIZE /* R1=Address of HW save area in reg array */ + add r1, r0, #SW_XCPT_SIZE /* R1=Address of HW save area in reg array */ ldmia r1, {r4-r11} /* Fetch eight registers in HW save area */ - ldr r1, [r0, #(4*REG_SP)] /* R1=Value of SP before interrupt */ + ldr r1, [r0, #(4*REG_SP)] /* R1=Value of SP before interrupt */ stmdb r1!, {r4-r11} /* Store eight registers in HW save area */ -#ifdef CONFIG_NUTTX_KERNEL +#ifdef CONFIG_NUTTX_KERNEL ldmia r0, {r2-r11,r14} /* Recover R4-R11, r14 + 2 temp values */ #else ldmia r0, {r2-r11} /* Recover R4-R11 + 2 temp values */ @@ -309,13 +350,33 @@ sam3u_common: /* We are returning with no context switch. We simply need to "unwind" * the same stack frame that we created + * + * Here: + * r1 = Address of the return stack (same as r0) */ 1: -#ifdef CONFIG_NUTTX_KERNEL +#ifdef CONFIG_NUTTX_KERNEL ldmia r1!, {r2-r11,r14} /* Recover R4-R11, r14 + 2 temp values */ #else ldmia r1!, {r2-r11} /* Recover R4-R11 + 2 temp values */ #endif + +#ifdef CONFIG_ARCH_FPU + /* Skip over the block of memory reserved for floating pointer register + * save. Then R1 is the address of the HW save area + */ + + add r1, #(4*SW_FPU_REGS) +#endif + + /* Set up to return from the exception + * + * Here: + * r1 = Address on the target thread's stack position at the start of + * the registers saved by hardware + * r3 = primask or basepri + * r4-r11 = restored register values + */ 2: #ifdef CONFIG_NUTTX_KERNEL /* The EXC_RETURN value will be 0xfffffff9 (privileged thread) or 0xfffffff1 |