Need to protect state on stack to do nested interrupt handling

7 files changed, 120 insertions, 71 deletions

diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index ba2493b8b..ea4f976a6 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -6283,3 +6283,9 @@
 	  beginning of SRAM.  It seems to require this alignament.  Also, we
 	  don't need different scripts for the CMNVECTOR case now that the vector
 	  table has a common name.
+	* arch/arm/src: armv-7/up_exception.S and xxx/xxx_vectors.S where
+	  xxx={kinetis, lm, lpc17xx, sam34, and stm32}:  Modified register usage
+	  when saving the context on the stack:  In order to handler nested
+	  interrupts, the stack pointer must be used so that when it is
+	  decremented, the contents on the stack are protected from the nested
+	  interrupt handling (2013-12-23).
diff --git a/nuttx/arch/arm/src/armv7-m/up_exception.S b/nuttx/arch/arm/src/armv7-m/up_exception.S
index 3eb8f97e3..517525415 100644
--- a/nuttx/arch/arm/src/armv7-m/up_exception.S
+++ b/nuttx/arch/arm/src/armv7-m/up_exception.S
@@ -126,11 +126,12 @@ exception_common:
 	/* The EXC_RETURN value tells us whether the context is on the MSP or PSP */
 
 	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
-	ite		eq						/* next two instructions conditional */
-	mrseq	r1, msp					/* R1=The main stack pointer */
-	mrsne	r1, psp					/* R1=The process stack pointer */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+1:
+	mov		r2, sp					/* R2=Copy of the main/process stack pointer */
 	add		r2, #HW_XCPT_SIZE		/* R2=MSP/PSP before the interrupt was taken */
 									/* (ignoring the xPSR[9] alignment bit) */
 #ifdef CONFIG_ARMV7M_USEBASEPRI
@@ -152,11 +153,11 @@ exception_common:
 	 * where to put the registers.
 	 */
 
-	vstmdb	r1!, {s16-s31}			/* Save the non-volatile FP context */
+	vstmdb	sp!, {s16-s31}			/* Save the non-volatile FP context */
 
 #endif
 
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP/PRIMASK values */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP/PRIMASK values */
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
 	/* Disable interrupts, select the stack to use for interrupt handling
@@ -174,6 +175,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -191,9 +200,8 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	msr	 msp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save area on stack */
-	mrs	 r1, msp					/* Recover R1=main stack pointer */
+	mrs		r1, msp					/* Get R1=main stack pointer */
 #endif
 
 	/* On return from up_doirq, R0 will hold a pointer to register context
@@ -202,7 +210,7 @@ exception_common:
 	 */
 
 	cmp		r0, r1					/* Context switch? */
-	beq		1f						/* Branch if no context switch */
+	beq		2f						/* Branch if no context switch */
 
 	/* 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
@@ -235,9 +243,9 @@ exception_common:
 	vldmia	r0, {s16-s31}			/* Recover S16-S31 */
 #endif
 
-	b		2f						/* Re-join common logic */
+	b		3f						/* Re-join common logic */
 
-1:
+2:
 	/* We are returning with no context switch.  We simply need to "unwind"
 	 * the same stack frame that we created at entry.
 	 */
@@ -247,7 +255,7 @@ exception_common:
 	vldmia  r1!, {s16-s31}			/* Recover S16-S31 */
 #endif
 
-2:
+3:
 	/* The EXC_RETURN value tells us whether we are returning on the MSP or PSP
 	 */
 
@@ -259,15 +267,15 @@ exception_common:
 
 	mrs		r2, control				/* R2=Contents of the control register */
 	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
-	beq		3f						/* Branch if privileged */
+	beq		4f						/* Branch if privileged */
 
 	orr		r2, r2, #1				/* Unprivileged mode */
 	msr		psp, r1					/* R1=The process stack pointer */
-	b		4f
-3:
+	b		5f
+4:
 	bic		r2, r2, #1				/* Privileged mode */
 	msr		msp, r1					/* R1=The main stack pointer */
-4:
+5:
 	msr		control, r2				/* Save the updated control register */
 #else
 	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
diff --git a/nuttx/arch/arm/src/kinetis/kinetis_vectors.S b/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
index 619f133a2..be597cfa9 100644
--- a/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
+++ b/nuttx/arch/arm/src/kinetis/kinetis_vectors.S
@@ -627,12 +627,12 @@ exception_common:
 	 * EXC_RETURN is 0xfffffffd (unprivileged thread)
 	 */
 
-	adds	r2, r14, #3				/* If R14=0xfffffffd, then r2 == 0 */
-	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 */
+	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
+
+1:
 #endif
 
 	/* r1 holds the value of the stack pointer AFTER the excption handling logic
@@ -640,7 +640,7 @@ exception_common:
 	 * stack pointer BEFORE the interrupt modified it.
 	 */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+	mov		r2, sp					/* 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
 	mrs		r3, basepri				/* R3=Current BASEPRI setting */
@@ -655,7 +655,7 @@ exception_common:
 	 * cannot be used in interrupt processing).
 	 */
 
-	sub		r1, #(4*SW_FPU_REGS)
+	sub		sp, #(4*SW_FPU_REGS)
 #endif
 
 	/* Save the remaining registers on the stack after the registers pushed
@@ -664,9 +664,9 @@ exception_common:
 	 */
 
 #ifdef CONFIG_NUTTX_KERNEL
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
 #else
-	stmdb	r1!, {r2-r11}			/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11}			/* Save the remaining registers plus the SP value */
 #endif
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
@@ -685,6 +685,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -702,7 +710,6 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	mov		sp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save (msp) */
 	mov		r1, sp					/* Recover R1=main stack pointer */
 #endif
diff --git a/nuttx/arch/arm/src/lm/lm_vectors.S b/nuttx/arch/arm/src/lm/lm_vectors.S
index 796ad5554..bdd65a543 100644
--- a/nuttx/arch/arm/src/lm/lm_vectors.S
+++ b/nuttx/arch/arm/src/lm/lm_vectors.S
@@ -230,12 +230,12 @@ exception_common:
 	 * EXC_RETURN is 0xfffffffd (unprivileged thread)
 	 */
 
-	adds	r2, r14, #3				/* If R14=0xfffffffd, then r2 == 0 */
-	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 */
+	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
+
+1:
 #endif
 
 	/* r1 holds the value of the stack pointer AFTER the excption handling logic
@@ -243,7 +243,7 @@ exception_common:
 	 * stack pointer BEFORE the interrupt modified it.
 	 */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+	mov		r2, sp					/* 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
 	mrs		r3, basepri				/* R3=Current BASEPRI setting */
@@ -258,7 +258,7 @@ exception_common:
 	 * cannot be used in interrupt processing).
 	 */
 
-	sub		r1, #(4*SW_FPU_REGS)
+	sub		sp, #(4*SW_FPU_REGS)
 #endif
 
 	/* Save the remaining registers on the stack after the registers pushed
@@ -267,9 +267,9 @@ exception_common:
 	 */
 
 #ifdef CONFIG_NUTTX_KERNEL
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
 #else
-	stmdb	r1!, {r2-r11}			/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11}			/* Save the remaining registers plus the SP value */
 #endif
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
@@ -288,6 +288,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -305,7 +313,6 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	mov		sp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save (msp) */
 	mov		r1, sp					/* Recover R1=main stack pointer */
 #endif
diff --git a/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S b/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
index 4be59a4d6..dc4a7a305 100644
--- a/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
+++ b/nuttx/arch/arm/src/lpc17xx/lpc17_vectors.S
@@ -239,12 +239,12 @@ exception_common:
 	 * EXC_RETURN is 0xfffffffd (unprivileged thread)
 	 */
 
-	adds	r2, r14, #3				/* If R14=0xfffffffd, then r2 == 0 */
-	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 */
+	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
+
+1:
 #endif
 
 	/* r1 holds the value of the stack pointer AFTER the excption handling logic
@@ -252,7 +252,7 @@ exception_common:
 	 * stack pointer BEFORE the interrupt modified it.
 	 */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+	mov		r2, sp					/* 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
 	mrs		r3, basepri				/* R3=Current BASEPRI setting */
@@ -267,7 +267,7 @@ exception_common:
 	 * cannot be used in interrupt processing).
 	 */
 
-	sub		r1, #(4*SW_FPU_REGS)
+	sub		sp, #(4*SW_FPU_REGS)
 #endif
 
 	/* Save the remaining registers on the stack after the registers pushed
@@ -276,9 +276,9 @@ exception_common:
 	 */
 
 #ifdef CONFIG_NUTTX_KERNEL
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
 #else
-	stmdb	r1!, {r2-r11}			/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11}			/* Save the remaining registers plus the SP value */
 #endif
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
@@ -297,6 +297,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -314,7 +322,6 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	mov		sp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save (msp) */
 	mov		r1, sp					/* Recover R1=main stack pointer */
 #endif
diff --git a/nuttx/arch/arm/src/sam34/sam_vectors.S b/nuttx/arch/arm/src/sam34/sam_vectors.S
index 4631ad13e..6ef3e2b80 100644
--- a/nuttx/arch/arm/src/sam34/sam_vectors.S
+++ b/nuttx/arch/arm/src/sam34/sam_vectors.S
@@ -244,12 +244,12 @@ exception_common:
 	 * EXC_RETURN is 0xfffffffd (unprivileged thread)
 	 */
 
-	adds	r2, r14, #3				/* If R14=0xfffffffd, then r2 == 0 */
-	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 */
+	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
+
+1:
 #endif
 
 	/* r1 holds the value of the stack pointer AFTER the excption handling logic
@@ -257,7 +257,7 @@ exception_common:
 	 * stack pointer BEFORE the interrupt modified it.
 	 */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+	mov		r2, sp					/* 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
 	mrs		r3, basepri				/* R3=Current BASEPRI setting */
@@ -272,7 +272,7 @@ exception_common:
 	 * cannot be used in interrupt processing).
 	 */
 
-	sub		r1, #(4*SW_FPU_REGS)
+	sub		sp, #(4*SW_FPU_REGS)
 #endif
 
 	/* Save the remaining registers on the stack after the registers pushed
@@ -281,9 +281,9 @@ exception_common:
 	 */
 
 #ifdef CONFIG_NUTTX_KERNEL
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
 #else
-	stmdb	r1!, {r2-r11}			/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11}			/* Save the remaining registers plus the SP value */
 #endif
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
@@ -302,6 +302,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -319,7 +327,6 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	mov		sp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save (msp) */
 	mov		r1, sp					/* Recover R1=main stack pointer */
 #endif
diff --git a/nuttx/arch/arm/src/stm32/stm32_vectors.S b/nuttx/arch/arm/src/stm32/stm32_vectors.S
index 00f4ebf59..da9eea46c 100644
--- a/nuttx/arch/arm/src/stm32/stm32_vectors.S
+++ b/nuttx/arch/arm/src/stm32/stm32_vectors.S
@@ -254,12 +254,12 @@ exception_common:
 	 * EXC_RETURN is 0xfffffffd (unprivileged thread)
 	 */
 
-	adds	r2, r14, #3				/* If R14=0xfffffffd, then r2 == 0 */
-	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 */
+	tst		r14, #EXC_RETURN_PROCESS_STACK /* nonzero if context on process stack */
+	beq		1f						/* Branch if context already on the MSP */
+	mrs		r1, psp					/* R1=The process stack pointer (PSP) */
+	mov     sp, r1					/* Set the MSP to the PSP */
+
+1:
 #endif
 
 	/* r1 holds the value of the stack pointer AFTER the excption handling logic
@@ -267,7 +267,7 @@ exception_common:
 	 * stack pointer BEFORE the interrupt modified it.
 	 */
 
-	mov		r2, r1					/* R2=Copy of the main/process stack pointer */
+	mov		r2, sp					/* 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
 	mrs		r3, basepri				/* R3=Current BASEPRI setting */
@@ -282,7 +282,7 @@ exception_common:
 	 * cannot be used in interrupt processing).
 	 */
 
-	sub		r1, #(4*SW_FPU_REGS)
+	sub		sp, #(4*SW_FPU_REGS)
 #endif
 
 	/* Save the remaining registers on the stack after the registers pushed
@@ -291,9 +291,9 @@ exception_common:
 	 */
 
 #ifdef CONFIG_NUTTX_KERNEL
-	stmdb	r1!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11,r14}		/* Save the remaining registers plus the SP value */
 #else
-	stmdb	r1!, {r2-r11}			/* Save the remaining registers plus the SP value */
+	stmdb	sp!, {r2-r11}			/* Save the remaining registers plus the SP value */
 #endif
 
 #ifndef CONFIG_ARCH_HIPRI_INTERRUPT
@@ -312,6 +312,14 @@ exception_common:
 	msr		basepri, r2				/* Set the BASEPRI */
 #endif
 
+	/* There are two arguments to up_doirq:
+	 *
+	 *   R0 = The IRQ number
+	 *   R1 = The top of the stack points to the saved state
+	 */
+
+	mov		r1, sp
+
 #if CONFIG_ARCH_INTERRUPTSTACK > 3
 	/* If CONFIG_ARCH_INTERRUPTSTACK is defined, we will set the MSP to use
 	 * a special special interrupt stack pointer.  The way that this is done
@@ -329,7 +337,6 @@ exception_common:
 	 * kernel mode).
 	 */
 
-	mov		sp, r1					/* We are using the main stack pointer */
 	bl		up_doirq				/* R0=IRQ, R1=register save (msp) */
 	mov		r1, sp					/* Recover R1=main stack pointer */
 #endif