Fixes from review.

- Change xmake config option into part of board config json.
- Rename low water mark to high water mark
- Introduce macros for CSR numbers in entry.S
- Formatting in tstack.h

Author: rmn30

sdk/core/loader/boot.cc

@@ -819,9 +819,9 @@ namespace
 			threadTStack->mstatus =
 			  (priv::MSTATUS_MPIE |
 			   (priv::MSTATUS_PRV_M << priv::MSTATUS_MPP_SHIFT));
-#ifdef CONFIG_MSLWM
-			threadTStack->mslwm  = stack.top();
-			threadTStack->mslwmb = stack.base();
+#ifdef CONFIG_MSHWM
+			threadTStack->mshwm  = stack.top();
+			threadTStack->mshwmb = stack.base();
 #endif
 			threadTStack->frameoffset = offsetof(TrustedStack, frames[1]);
 			threadTStack->frames[0].calleeExportTable =

sdk/core/switcher/entry.S

@@ -6,6 +6,18 @@
 
 .include "assembly-helpers.s"
 
+#  Symbolic names for the satck high water mark registers until
+#  the assembler knows about them.
+
+/**
+ * Machine-mode stack high water mark CSR
+ */
+#define CSR_MSHWM  0xbc1
+/**
+ * Machine mode stack high water mark stack base CSR
+ */
+#define CSR_MSHWMB 0xbc2
+
 #define MAX_FAULTS_PER_COMPARTMENT_CALL 1024
 
 # Global for the sealing key.  Stored in the switcher's code section.
@@ -182,21 +194,21 @@ compartment_switcher_entry:
 	sub                s1, s0, s1
 	csetboundsexact    ct2, csp, s1
 	csetaddr           csp, ct2, s0
-#ifdef CONFIG_MSLWM
-	// read and align the stack low water mark
-	csrr               gp, 0xbc1 // mslwm
+#ifdef CONFIG_MSHWM
+	// read and align the stack high water mark
+	csrr               gp, CSR_MSHWM
 	and                gp, gp, ~0xf
-	// skip zeroing if low water mark >= stack poitner
+	// skip zeroing if high water mark >= stack poitner
 	bge                t2, sp, after_zero
-	// use stack low water mark as base address for zeroing
+	// use stack high water mark as base address for zeroing
 	// XXX could be out of bounds / unrepresentable if bad csp?
 	csetaddr           ct2, csp, gp
 #endif
 	zero_stack         t2, s0, gp
 after_zero:
-#ifdef CONFIG_MSLWM
-	// store new stack top as stack low water mark
-	csrw               0xbc1, sp // mslwm
+#ifdef CONFIG_MSHWM
+	// store new stack top as stack high water mark
+	csrw               CSR_MSHWM, sp
 #endif
 #endif // CONFIG_NO_SWITCHER_SAFETY
 .Lout:
@@ -330,11 +342,11 @@ exception_entry_asm:
 	csc                ct0, TrustedStack_offset_mepcc(csp)
 	csrr               t1, mstatus
 	csw                t1, TrustedStack_offset_mstatus(csp)
-#ifdef CONFIG_MSLWM
-	csrr               t1, 0xbc1 // mslwm
-	csw                t1, TrustedStack_offset_mslwm(csp)
-	csrr               t1, 0xbc2 // mslwmb
-	csw                t1, TrustedStack_offset_mslwmb(csp)
+#ifdef CONFIG_MSHWM
+	csrr               t1, CSR_MSHWM
+	csw                t1, TrustedStack_offset_mshwm(csp)
+	csrr               t1, CSR_MSHWMB
+	csw                t1, TrustedStack_offset_mshwmb(csp)
 #endif
 	csrr               t1, mcause
 	csw                t1, TrustedStack_offset_mcause(csp)
@@ -415,11 +427,11 @@ exception_entry_asm:
 .Linstall_context:
 	clw                x1, TrustedStack_offset_mstatus(csp)
 	csrw               mstatus, x1
-#ifdef CONFIG_MSLWM
-	clw                x1, TrustedStack_offset_mslwm(csp)
-	csrw               0xbc1, x1 // mslwm
-	clw                x1, TrustedStack_offset_mslwmb(csp)
-	csrw               0xbc2, x1 // mslwmb
+#ifdef CONFIG_MSHWM
+	clw                x1, TrustedStack_offset_mshwm(csp)
+	csrw               CSR_MSHWM, x1
+	clw                x1, TrustedStack_offset_mshwmb(csp)
+	csrw               CSR_MSHWMB, x1
 #endif
 	cspecialw          mepcc, ct2
 	csb                zero, TrustedStack_offset_inForcedUnwind(csp)
@@ -721,21 +733,21 @@ exception_entry_asm:
 	// Update the current frame offset.
 	csw                t2, TrustedStack_offset_frameoffset(ctp)
 #ifndef CONFIG_NO_SWITCHER_SAFETY
-#ifdef CONFIG_MSLWM
-	// read and align the stack low water mark
+#ifdef CONFIG_MSHWM
+	// read and align the stack high water mark
 	// we will use this as base address for stack clearing
 	// note that it cannot be greater than stack top as we 
 	// we set it to stack top when we pushed to trusted stack frame
-	csrr               tp, 0xbc1 //mslwm
+	csrr               tp, CSR_MSHWM
 	and                tp, tp, ~0xf
 #else
 	cgetbase           tp, csp
 #endif
 	cgetaddr           t1, csp
 	csetaddr           ct2, csp, tp
 	zero_stack         t2, t1, tp
-#ifdef CONFIG_MSLWM
-	csrw               0xbc1, sp // mslwm
+#ifdef CONFIG_MSHWM
+	csrw               CSR_MSHWM, sp
 #endif
 #endif // CONFIG_NO_SWITCHER_SAFETY
 	cret

sdk/core/switcher/trusted-stack-assembly.h

@@ -21,9 +21,9 @@ EXPORT_ASSEMBLY_OFFSET(TrustedStack, c14, 14 * 8)
 EXPORT_ASSEMBLY_OFFSET(TrustedStack, c15, 15 * 8)
 EXPORT_ASSEMBLY_OFFSET(TrustedStack, mstatus, 16 * 8)
 EXPORT_ASSEMBLY_OFFSET(TrustedStack, mcause, (16 * 8) + 4)
-#ifdef CONFIG_MSLWM
-EXPORT_ASSEMBLY_OFFSET(TrustedStack, mslwm, 17 * 8)
-EXPORT_ASSEMBLY_OFFSET(TrustedStack, mslwmb, (17 * 8) + 4)
+#ifdef CONFIG_MSHWM
+EXPORT_ASSEMBLY_OFFSET(TrustedStack, mshwm, 17 * 8)
+EXPORT_ASSEMBLY_OFFSET(TrustedStack, mshwmb, (17 * 8) + 4)
 
 // Size of everything up to this point
 #define TSTACK_REGFRAME_SZ (18 * 8)

sdk/core/switcher/tstack.h

@@ -62,9 +62,9 @@ struct TrustedStackGeneric
 	void  *c15;
 	size_t mstatus;
 	size_t mcause;
-#ifdef CONFIG_MSLWM
-	uint32_t mslwm;
-	uint32_t mslwmb;
+#ifdef CONFIG_MSHWM
+	uint32_t mshwm;
+	uint32_t mshwmb;
 #endif
 	uint16_t frameoffset;
 	/**
@@ -73,12 +73,13 @@ struct TrustedStackGeneric
 	 */
 	uint8_t inForcedUnwind;
 	// Padding up to multiple of 16-bytes.
-#ifdef CONFIG_MSLWM
-#	define TRUSTED_STACK_PADDING 13
+	uint8_t padding[
+#ifdef CONFIG_MSHWM
+	  13
 #else
-#	define TRUSTED_STACK_PADDING 5
+	  5
 #endif
-	uint8_t padding[TRUSTED_STACK_PADDING];
+	];
 	/**
 	 * The trusted stack.  There is always one frame, describing the entry
 	 * point.  If this is popped then we have run off the stack and the thread

sdk/xmake.lua

@@ -16,11 +16,6 @@ option("scheduler-accounting")
 	set_description("Track per-thread cycle counts in the scheduler");
 	set_showmenu(true)
 
-option("stack-low-water-mark")
-	set_default(false)
-	set_description("Build with support for stack low water mark");
-	set_showmenu(true)
-
 function debugOption(name)
 	option("debug-" .. name)
 		set_default(false)
@@ -237,8 +232,9 @@ rule("firmware")
 			add_defines("SIMULATION")
 		end
 
-		if get_config("stack-low-water-mark") then
-			add_defines("CONFIG_MSLWM")
+		if board.stack_high_water_mark then
+			print("using stack high water mark")
+			add_defines("CONFIG_MSHWM")
 		end
 
 		-- Build the MMIO space for the board