From 36f2d87ee57e841be5fe60f6430bdd167f9f03af Mon Sep 17 00:00:00 2001
From: Christian Cunningham <cc@localhost>
Date: Tue, 1 Feb 2022 17:19:16 -0700
Subject: Added spinlock condition

---
 Common.mk                 | 2 +-
 include/cpu/atomic/swap.h | 3 ++-
 linker.ld                 | 2 +-
 src/exceptions/svc.S      | 5 +----
 4 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/Common.mk b/Common.mk
index 04bf399..69828e6 100644
--- a/Common.mk
+++ b/Common.mk
@@ -26,7 +26,7 @@ ifeq ($(BSP),2)
 	CFLAGS += -DBSP23
 endif
 
-CFLAGS += -DVERSION="\"0.0s\""
+CFLAGS += -DVERSION="\"0.1a\""
 
 .PHONY: clean run run-debug debug export tree
 
diff --git a/include/cpu/atomic/swap.h b/include/cpu/atomic/swap.h
index ebaaa1d..57a5add 100644
--- a/include/cpu/atomic/swap.h
+++ b/include/cpu/atomic/swap.h
@@ -13,7 +13,8 @@ static inline void atm_lock(unsigned long pid, unsigned long* addr)
 {
 	unsigned long tmp, current_lock_value;
 	asm volatile(
-"1:	ldrex	%0, [%3]\n"
+"1:	clrex\n"
+"	ldrex	%0, [%3]\n"
 "	cmp	%0, #0\n"
 "	wfene\n"
 "	strexeq	%1, %2, [%3]\n"
diff --git a/linker.ld b/linker.ld
index b7048ab..260e1f1 100644
--- a/linker.ld
+++ b/linker.ld
@@ -13,7 +13,7 @@ SECTIONS
         KEEP(*(.text.kernel))
         *(.text*)
     }
-    . = ALIGN(4096); /* align to page size */
+    . = 0x208000; /* 2MiB Kernel/ Boot */
     __text_end = .;
  
     __data_start = .;
diff --git a/src/exceptions/svc.S b/src/exceptions/svc.S
index a5e9982..d1fcbc0 100644
--- a/src/exceptions/svc.S
+++ b/src/exceptions/svc.S
@@ -5,9 +5,6 @@ svc:
 	stmfd sp!, {r0-r12,lr}
 	ldr r0, [lr, #-4]
 	bic r0, #0xFF000000
-	// SVC #0 returns to supervisor mode
-	// TODO: Make supervisor mode return to a specific location
-	//  (rather than to a user location) such as the kernel loop
 	cmp r0, #3
 	bgt svc_exit
 	beq svc_000003
@@ -27,7 +24,7 @@ svc_000002:
 	b schedule
 svc_000003:
 	ldr r3, =scheduler
-	ldr r2, [r3, #0]
+	ldr r2, [r3, #0] // struct Thread* rthread
 	ldr r1, [r2, #8] // sp_base
 	cmp r1, #-1
 	beq svc_exit
-- 
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