[Barrelfish-users] Make armv7 cpu driver run in SVC mode

[Wang Nan]

Hi,

As I mentioned early, I provide a patch on armv7, which makes cpu driver executes on ARMv7 platform, and fixes
the cpsr clobber problem. This patch should be applied after my CLREX patch.

For all arm platform:

diff --git a/kernel/arch/arm/exec.c b/kernel/arch/arm/exec.c
index e73e437..fdeb1ed 100644
--- a/kernel/arch/arm/exec.c
+++ b/kernel/arch/arm/exec.c
@@ -63,7 +63,11 @@ void do_resume(uint32_t *regs)
         /* "ldmia  lr!, {r13}                              \n\t" */
         /* // Restore LR and PC */
         /* "ldmia  lr!, {r14-r15}                          \n\t" */
-        "ldmia  %[regs], {r0-r15}^                          \n\t"
+	"mov lr, %[regs]\n\t"
+	"ldmia lr, {r0 - lr}^\n\t"
+	"add lr, #4*15\n\t"
+	"ldr lr, [lr]\n\t"
+	"movs pc, lr\n\t"
         // Make sure pipeline is clear
         "nop                          \n\t"
         "nop                          \n\t"
@@ -148,7 +152,7 @@ void wait_for_interrupt(void)
     // Switch to priviledged mode with interrupts enabled.
     __asm volatile(
         //"mov    r0, #" XTR(ARM_MODE_SYS) "              \n\t"
-        "mov    r0, #" XTR(ARM_MODE_PRIV) "              \n\t"
+        "mov    r0, #" XTR(ARM_MODE_SVC) "              \n\t"
         "msr    cpsr_c, r0                              \n\t"
         "0:                                             \n\t"
 #if defined(__ARM_ARCH_6K__)
diff --git a/kernel/arch/armv7/exceptions.S b/kernel/arch/armv7/exceptions.S
index 14e20af..e8e403a 100644
--- a/kernel/arch/armv7/exceptions.S
+++ b/kernel/arch/armv7/exceptions.S
@@ -57,11 +57,6 @@ undef_stack:
 undef_stack_top:
         .space 8, 0

-svc_stack:
-        .space EXCEPTION_MODE_STACK_BYTES, 0
-svc_stack_top:
-        .space 8, 0
-
         //
         // System mode stack
         //
@@ -112,9 +107,6 @@ $exceptions_load_stacks:
         mov     r0, # ARM_MODE_UND
         ldr     r1, = undef_stack_top
         bl      set_stack_for_mode
-        mov     r0, # ARM_MODE_SVC
-        ldr     r1, = svc_stack_top
-        bl      set_stack_for_mode
 $exceptions_install_handlers:
         mov     r0, # ARM_EVECTOR_PABT
         adr     r1, pabt_handler
@@ -262,7 +254,7 @@ null_handler:
         //
 .macro enter_sys scratch
 	clrex
-        mov \scratch, #(CPSR_IF_MASK | ARM_MODE_SYS)
+        mov \scratch, #(CPSR_IF_MASK | ARM_MODE_SVC)
         msr cpsr_c, \scratch
         init_sys_pic_register
         init_sys_stack



Omap specific code (I don't have pandaboard platform, so following code has not been tested yet)

--- a/kernel/arch/???/boot.S
+++ b/kernel/arch/???/boot.S
@@ -24,7 +24,7 @@ start:
         //
         mrs     r3, cpsr
         bic     r3, r3, #ARM_MODE_MASK
-        orr     r3, r3, #ARM_MODE_PRIV  // Ensure in privileged mode
+        orr     r3, r3, #ARM_MODE_SVC  // Ensure in privileged mode
         msr     cpsr_c, r3		// _c => don't change cond. codes