change syscalls to take 5 params and return 6

+ In total, a syscall is built up of 6 values, with the first being the
  syscall number. Symmetrically, the first value is now a status and the
  following five values return "values". This allows us to cram in more
  info into the ipc_* functions. The performance difference is
  absolutely minimal, at least from my testing in qemu.

8 files changed, 49 insertions, 22 deletions

diff --git a/arch/riscv64/asm/asm-offsets.c b/arch/riscv64/asm/asm-offsets.c
index 8852d8f..3619765 100644
--- a/arch/riscv64/asm/asm-offsets.c
+++ b/arch/riscv64/asm/asm-offsets.c
@@ -8,6 +8,7 @@
  */
 
 #include <apos/utils.h>
+#include <apos/uapi.h>
 #include "../kernel/regs.h"
 
 /**
@@ -74,4 +75,12 @@ void asm_offsets()
 	OFFSETOF(t5, struct riscv_regs);
 	OFFSETOF(t6, struct riscv_regs);
 	SIZEOF(registers, struct riscv_regs);
+
+	OFFSETOF(s, struct sys_ret);
+	OFFSETOF(ar0, struct sys_ret);
+	OFFSETOF(ar1, struct sys_ret);
+	OFFSETOF(ar2, struct sys_ret);
+	OFFSETOF(ar3, struct sys_ret);
+	OFFSETOF(ar4, struct sys_ret);
+	SIZEOF(sys_ret, struct sys_ret);
 }
diff --git a/arch/riscv64/asm/source.mk b/arch/riscv64/asm/source.mk
index 9b463b7..87bcf24 100644
--- a/arch/riscv64/asm/source.mk
+++ b/arch/riscv64/asm/source.mk
@@ -9,7 +9,7 @@ $(OFFSET_HEADER): $(OFFSET_SOURCE)
 	echo " * @file asm-offsets.h" >> $(OFFSET_HEADER)
 	echo " * This comment is to shut up warnings." >> $(OFFSET_HEADER)
 	echo " */" >> $(OFFSET_HEADER)
-	$(COMPILER) $(INCLUDE_FLAGS) -S $(OFFSET_SOURCE) -o - |\
+	$(COMPILER) $(CFLAGS) $(INCLUDE_FLAGS) -S $(OFFSET_SOURCE) -o - |\
 		awk '($$1 == "#->") { print "#define " $$2 " " $$3 }' >> $(OFFSET_HEADER)
 	echo "#endif /* APOS_ASM_OFFSETS_H */" >> $(OFFSET_HEADER)
 
diff --git a/arch/riscv64/conf/init b/arch/riscv64/conf/init
index d9a585d..b75076f 100755
--- a/arch/riscv64/conf/init
+++ b/arch/riscv64/conf/init
diff --git a/arch/riscv64/conf/init.c b/arch/riscv64/conf/init.c
index 4bd6a4e..feb5177 100644
--- a/arch/riscv64/conf/init.c
+++ b/arch/riscv64/conf/init.c
@@ -9,30 +9,33 @@
 #include <stdint.h>
 #include "../../../include/apos/syscalls.h"
 
+#define ecall() do { asm ("ecall" : : : "a0", "a1", "a2", "a3", "a4", "a5"); \
+} while (0)
 static void sys_noop()
 {
 	long register a0 asm ("a0") = SYS_NOOP;
-	asm ("ecall" : : : "a0", "a1");
+	ecall();
 }
 
 static void sys_putch(char c)
 {
 	long register a0 asm ("a0") = SYS_PUTCH;
 	long register a1 asm ("a1") = c;
-	asm ("ecall" : : : "a0", "a1");
+	ecall();
 }
 
 static uint64_t sys_timebase()
 {
 	long register a0 asm ("a0") = SYS_TIMEBASE;
 	long register a1 asm ("a1") = 0;
-	asm ("ecall" : : : "a0", "a1");
+	long register a2 asm ("a2") = 0;
+	ecall();
 #if defined(_LP64)
 	return a1;
 #else
-	uint64_t t = a0;
+	uint64_t t = a1;
 	t <<= 32;
-	return t + a1;
+	return t + a2;
 #endif
 }
 
@@ -40,13 +43,14 @@ static uint64_t sys_ticks()
 {
 	long register a0 asm ("a0") = SYS_TICKS;
 	long register a1 asm ("a1") = 0;
-	asm ("ecall" : : : "a0", "a1");
+	long register a2 asm ("a2") = 0;
+	ecall();
 #if defined(_LP64)
 	return a1;
 #else
-	uint64_t t = a0;
+	uint64_t t = a1;
 	t <<= 32;
-	return t + a1;
+	return t + a2;
 #endif
 }
 
diff --git a/arch/riscv64/conf/initrd b/arch/riscv64/conf/initrd
index f05e035..3af4d2e 100644
--- a/arch/riscv64/conf/initrd
+++ b/arch/riscv64/conf/initrd
diff --git a/arch/riscv64/init/init.c b/arch/riscv64/init/init.c
index 0680296..498023a 100644
--- a/arch/riscv64/init/init.c
+++ b/arch/riscv64/init/init.c
@@ -44,7 +44,8 @@ static void init_bootmem()
 
 	/* direct mapping (temp) */
 	for (size_t i = 0; i < CSTACK_PAGE; ++i)
-		root_branch->leaf[i] = (struct vmem *)to_pte(TOP_PAGE_SIZE * i, flags);
+		root_branch->leaf[i] = (struct vmem *)to_pte(TOP_PAGE_SIZE * i,
+		                                             flags);
 
 	/* kernel (also sort of direct mapping) */
 	flags |= VM_G;
diff --git a/arch/riscv64/kernel/entry.S b/arch/riscv64/kernel/entry.S
index 1bd6046..8ff642a 100644
--- a/arch/riscv64/kernel/entry.S
+++ b/arch/riscv64/kernel/entry.S
@@ -86,25 +86,42 @@ handle_syscall:
 	/* add 4 (size of ecall) to EPC to avoid running the same instruction
 	 * twice */
 	csrr    s0, CSR_SEPC
-	addi s0, s0, 4
+	addi	s0, s0, 4
 	csrw	CSR_SEPC, s0
+	/* allocate space for sys_ret structure on stack and shift argument
+	 * registers down one to make room for the pointer to this structure */
+	addi	sp, sp, -sizeof_sys_ret
+	mv	a6, a5
+	mv	a5, a4
+	mv	a4, a3
+	mv	a3, a2
+	mv	a2, a1
+	mv	a1, a0
+	mv	a0, sp
 	jal	syscall_dispatch
+	/* move structure from stack into registers. */
+	lr	a0, offsetof_s(sp)
+	lr	a1, offsetof_ar0(sp)
+	lr	a2, offsetof_ar1(sp)
+	lr	a3, offsetof_ar2(sp)
+	lr	a4, offsetof_ar3(sp)
+	lr	a5, offsetof_ar4(sp)
+	addi	sp, sp, sizeof_sys_ret
 	/* if we had a thread switch, load kernel stack of current thread and
 	 * restore its context */
-	/* TODO: is a whole function call necessary? */
-	mv	s0, a0
-	mv	s1, a1
 	/* get associated kernel stack */
 	mv	sp, tp
 	addi	sp, sp, -sizeof_registers
 	/* restore system call result */
-	mv	a0, s0
-	mv	a1, s1
 	j	restore_noreturn
 
 restore_all:
 	lr	a0, offsetof_a0(sp)
 	lr      a1, offsetof_a1(sp)
+	lr      a2, offsetof_a2(sp)
+	lr      a3, offsetof_a3(sp)
+	lr      a4, offsetof_a4(sp)
+	lr      a5, offsetof_a5(sp)
 
 restore_noreturn:
 	/* restore registers besides possible return value, assume instruction
@@ -117,11 +134,7 @@ restore_noreturn:
 	lr      t0, offsetof_t0(sp)
 	lr      t1, offsetof_t1(sp)
 	lr      t2, offsetof_t2(sp)
-	/* a0 and a1 should not be restored when coming from a syscall */
-	lr      a2, offsetof_a2(sp)
-	lr      a3, offsetof_a3(sp)
-	lr      a4, offsetof_a4(sp)
-	lr      a5, offsetof_a5(sp)
+	/* a0 - a5 should not be restored when coming from a syscall */
 	lr      a6, offsetof_a6(sp)
 	lr	s0, offsetof_s0(sp)
 	lr	s1, offsetof_s1(sp)
diff --git a/arch/riscv64/kernel/vmem.c b/arch/riscv64/kernel/vmem.c
index 1abc58d..a029f6a 100644
--- a/arch/riscv64/kernel/vmem.c
+++ b/arch/riscv64/kernel/vmem.c
@@ -306,7 +306,7 @@ vm_t setup_kernel_io(struct vmem *b, vm_t paddr)
 {
 	pm_t top_page = paddr / TOP_PAGE_SIZE;
 	b->leaf[IO_PAGE] = (struct vmem *)to_pte(top_page * TOP_PAGE_SIZE,
-			VM_V | VM_R | VM_W);
+	                                         VM_V | VM_R | VM_W);
 	return -TOP_PAGE_SIZE + paddr - (top_page * TOP_PAGE_SIZE);
 }
 #endif