SELFOUR-526: ARM - Unify C entry point for system calls

include/arch/arm/arch/32/mode/fastpath/fastpath.h

@@ -16,6 +16,7 @@
 #include <arch/linker.h>
 #include <api/types.h>
 #include <api/syscall.h>
+#include <armv/context_switch.h>
 
 /* When building the fastpath the assembler in traps.S makes these
  * assumptions. Because compile_asserts are hard to do in assembler,

include/arch/arm/arch/fastpath/fastpath.h

@@ -17,8 +17,23 @@
 void slowpath(syscall_t syscall)
 VISIBLE NORETURN;
 
-void fastpath_restore(word_t badge, word_t msgInfo, tcb_t *cur_thread)
-VISIBLE NORETURN;
+static inline void NORETURN fastpath_restore(word_t badge, word_t msgInfo, tcb_t *cur_thread)
+{
+    register word_t badge_reg asm("r0") = badge;
+    register word_t msgInfo_reg asm("r1") = msgInfo;
+    register word_t cur_thread_reg asm("r2") = (word_t)cur_thread;
+    asm volatile("mov sp, r2 \n\
+                  add sp, sp, %[LR_SVC_OFFSET] \n\
+                  ldmdb sp, {r2-lr}^ \n\
+                  rfeia sp"
+                 :
+                 : [badge]"r"(badge_reg),
+                 [msginfo]"r"(msgInfo_reg),
+                 [cur_thread]"r"(cur_thread_reg),
+                 [LR_SVC_OFFSET]"i"(LR_svc * sizeof(word_t))
+                 : "memory");
+    UNREACHABLE();
+}
 
 void fastpath_call(word_t cptr, word_t r_msgInfo)
 VISIBLE NORETURN SECTION(".vectors.fastpath_call");

include/kernel/traps.h

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2016, General Dynamics C4 Systems
+ *
+ * This software may be distributed and modified according to the terms of
+ * the GNU General Public License version 2. Note that NO WARRANTY is provided.
+ * See "LICENSE_GPLv2.txt" for details.
+ *
+ * @TAG(GD_GPL)
+ */
+
+#ifndef __KERNEL_TRAPS_H
+#define __KERNEL_TRAPS_H
+
+#include <config.h>
+#include <util.h>
+
+void c_handle_syscall(word_t cptr, word_t msgInfo, syscall_t syscall)
+VISIBLE SECTION(".vectors.text");
+
+#endif /* __KERNEL_TRAPS_H */

include/util.h

@@ -38,6 +38,7 @@
 #define UNUSED       __attribute__((unused))
 #define USED         __attribute__((used))
 #define FASTCALL     __attribute__((fastcall))
+#define UNREACHABLE()  __builtin_unreachable()
 
 #define OFFSETOF(type, member) \
     __builtin_offsetof(type, member)

src/arch/arm/32/Makefile

@@ -15,6 +15,8 @@ include ${SOURCE_ROOT}/src/arch/$(ARCH)/32/kernel/Makefile
 include ${SOURCE_ROOT}/src/arch/$(ARCH)/32/model/Makefile
 include ${SOURCE_ROOT}/src/arch/$(ARCH)/32/machine/Makefile
 
+ARCH_C_SOURCES   += 32/c_traps.c
+
 ARCH_ASM_SOURCES += 32/halt.S \
                     32/head.S \
                     32/idle.S \

src/arch/arm/32/c_traps.c

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2014, General Dynamics C4 Systems
+ *
+ * This software may be distributed and modified according to the terms of
+ * the GNU General Public License version 2. Note that NO WARRANTY is provided.
+ * See "LICENSE_GPLv2.txt" for details.
+ *
+ * @TAG(GD_GPL)
+ */
+
+#include <config.h>
+#include <model/statedata.h>
+#include <arch/fastpath/fastpath.h>
+#include <kernel/traps.h>
+
+#include <api/syscall.h>
+
+void VISIBLE c_handle_syscall(word_t cptr, word_t msgInfo, syscall_t syscall)
+{
+#ifdef CONFIG_FASTPATH
+    if (syscall == SysCall) {
+        fastpath_call(cptr, msgInfo);
+    } else if (syscall == SysReplyRecv) {
+        fastpath_reply_recv(cptr, msgInfo);
+    }
+#endif /* CONFIG_FASTPATH */
+
+    if (unlikely(syscall < SYSCALL_MIN || syscall > SYSCALL_MAX)) {
+        handleUnknownSyscall(syscall);
+    } else {
+        slowpath(syscall);
+    }
+}

src/arch/arm/32/traps.S

@@ -93,30 +93,12 @@ BEGIN_FUNC(arm_swi_syscall)
     /* Store FaultInstruction */
     str lr, [sp, #(PT_FaultInstruction - PT_LR_svc)]
 
-#ifdef FASTPATH
-    cmp r7, #SYSCALL_REPLY_RECV
-#endif
-
     /* Stack all user registers */
     stmdb sp, {r0-lr}^
 
     /* Load the kernel's real stack pointer */
     ldr sp, =(PPTR_KERNEL_STACK_TOP)
 
-#ifdef FASTPATH
-    /*
-     * Call is -1 == 0xffffffff.
-     * We compared against -2 = 0xfffffffe above.
-     * Performing an unsigned higher than, there is only one unsigned number
-     * greater than -2.
-     */
-    bhi fastpath_call
-    beq fastpath_reply_recv
-#endif
-
-    /* Load system call number for handleSyscall and handleUnknownSyscall() */
-    mov r0, r7
-
     /*
      * RET_TO_USER needs ksCurThread. We can issue the load here where we have
      * some spare cycles, and the ARM ABI will preserve it across function
@@ -124,12 +106,11 @@ BEGIN_FUNC(arm_swi_syscall)
      */
     ldr r8, =ksCurThread
 
-    /* Check that syscall number is in range */
-    add r2, r0, #(-SYSCALL_MIN)
-    cmp r2, #(SYSCALL_MAX - SYSCALL_MIN + 1)
-    bhs arm_swi_undefined_syscall
-
-    blx handleSyscall
+    /* Load system call number as a c_handle_syscall argument. r0 and r1 are passed
+     * unmodified (cptr and msgIngo respectively.
+     */
+    mov r2, r7
+    blx c_handle_syscall
 
     /* Return to user. */
     RET_TO_USER r8
@@ -152,17 +133,6 @@ BEGIN_FUNC(slowpath)
     RET_TO_USER r7
 END_FUNC(slowpath)
 
-BEGIN_FUNC(fastpath_restore)
-    /* Duplicate of above except r2 contains ksCurThread,
-       r0 and r1 should be preserved */
-    mov sp, r2
-    add sp, sp, #PT_LR_svc
-
-    ldmdb sp, {r2-lr}^
-
-    rfeia sp
-END_FUNC(fastpath_restore)
-
 BEGIN_FUNC(arm_prefetch_abort_exception)
     /* Full save/restore, documented in arm_swi_syscall */
     srsia #PMODE_SUPERVISOR