SMC test code

* avoid trampling r4
 * changed from -march=armv7-a to -mcpu=cortex-a7 to enable SMC instruction (why?)

Makefile

@@ -12,7 +12,7 @@ OBJCOPY = $(PREFIX)objcopy
 
 LIBGCC = $(shell $(CC) -print-libgcc-file-name)
 
-CFLAGS_ALL = -Wall -Werror -ffreestanding -nostdinc -march=armv7-a -std=c99 -g -O -I include -I pdclib/include
+CFLAGS_ALL = -Wall -Werror -ffreestanding -nostdinc -mcpu=cortex-a7 -std=c99 -g -O -I include -I pdclib/include
 LDFLAGS_ALL = -nostdlib
 
 all: piimage/kevlar.img
@@ -27,8 +27,8 @@ qemu: piimage/kevlar.img
 qemugdb: piimage/kevlar.img
 	qemu-system-arm $(QEMU_ARGS) -bios $< -S
 
-gdb: piloader/piloader.elf
-	$(PREFIX)gdb --symbols=$< -ex 'target remote :1234'
+gdb: piimage/kevlar.elf
+	$(PREFIX)gdb -ex 'target remote :1234'
 
 dir := pdclib
 include $(dir)/subdir.mk

monitor/entry.S

@@ -33,9 +33,9 @@ _monitor_vectors:
 
 _monitor_start: /* start of day entry, invoked only by the loader */
         /* compute stack and switch to it */
-        getstackaddr ip, r4
-        stmdb   r4!, {sp,lr}
-        mov     sp, r4
+        getstackaddr ip, r3
+        stmdb   r3!, {sp,lr}
+        mov     sp, r3
 
         /* call C */
         bl      monitor_start
@@ -49,8 +49,9 @@ _smchandler:
         /* TODO: figure out calling convention, and which registers to pass/save */
        
         /* call C */
-        getstackaddr ip, r4
-        stmdb   r4!, {sp,lr}
+        getstackaddr ip, r3
+        stmdb   r3!, {sp,lr}
+        mov     sp, r3
         bl      smchandler
 
         /* TODO: scrub secrets from registers */

monitor/smchandler.c

@@ -1,3 +1,6 @@
-void smchandler(void)
+#include <stdint.h>
+
+uintptr_t smchandler(void)
 {
+    return 0x37;
 }

piloader/main.c

@@ -152,6 +152,30 @@ static void map_l2_pages(armpte_short_l2 *l2pt, uintptr_t vaddr, uintptr_t paddr
     }
 }
 
+static uintptr_t smc(uint8_t imm, uintptr_t arg0, uintptr_t arg1, uintptr_t arg2)
+{
+    register uintptr_t r0 __asm("r0") = arg0;
+    register uintptr_t r1 __asm("r1") = arg1;
+    register uintptr_t r2 __asm("r2") = arg2;
+
+    __asm("smc %3"
+          : "+r" (r0), "+r" (r1), "+r" (r2)
+          : "M" (imm), "0" (r0), "1" (r1), "2" (r2)
+          : "r3"
+          );
+
+    return r0;
+}
+
+static void smc_test(void)
+{
+    console_printf("SMC test...\n");
+
+    uintptr_t ret = smc(0,0,0,0);
+
+    console_printf("SMC returned: %lx\n", ret);
+}
+
 void __attribute__((noreturn)) main(void)
 {
     uint8_t coreid = mycoreid();
@@ -246,7 +270,11 @@ void __attribute__((noreturn)) main(void)
     __asm volatile("mcr p15, 0, %0, c1, c1, 0" : : "r" (reg));
     __asm volatile("isb");
 
-    console_printf("exited secure world, entering kernel...\n");
+    console_printf("exited secure world\n");
+
+    smc_test();
+    
+    console_printf("entering kernel...\n");
     typedef void kernel_entry(uintptr_t zero, uintptr_t boardid, void *atags);
     ((kernel_entry *)0x8000)(0, 0xc43, (void *)0x100);