From 1d20df331cb4540bac157ac779d035d189ef669c Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Fri, 8 Jul 2022 21:11:10 +0200
Subject: kernel/syscalls: fix the SYSCALL_RETURN macro for returning pointers

---
 Makefile              |  3 ++-
 src/kernel/syscalls.c | 15 +++++++--------
 2 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index bf0f1f6..98397ca 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,7 @@ CHECK   = sparse
 CFLAGS += -g -std=gnu99 -ffreestanding -O2 -Wall -Wextra -Wold-style-definition -Werror=implicit-function-declaration -ftrack-macro-expansion=0
 CFLAGS += -mgeneral-regs-only
 CFLAGS += -Isrc/
+SPARSEFLAGS = -Wno-non-pointer-null
 LFLAGS  = -ffreestanding -O2 -nostdlib -lgcc
 QFLAGS  = -no-reboot
 ifndef QEMU_DISPLAY
@@ -45,7 +46,7 @@ lint:
 	@tools/linter/main.rb
 
 check: $(shell find src/kernel/ -type f -name *.c)
-	@echo $^ | xargs -n 1 sparse $(CFLAGS)
+	@echo $^ | xargs -n 1 sparse $(CFLAGS) $(SPARSEFLAGS)
 
 clean:
 	rm -rv out/
diff --git a/src/kernel/syscalls.c b/src/kernel/syscalls.c
index e639d1f..cfd895e 100644
--- a/src/kernel/syscalls.c
+++ b/src/kernel/syscalls.c
@@ -11,8 +11,10 @@
 #include <stdint.h>
 
 #define SYSCALL_RETURN(val) do { \
+	uint32_t ret = (uint32_t)val; \
 	assert(process_current->state == PS_RUNNING); \
-	return regs_savereturn(&process_current->regs, val); \
+	regs_savereturn(&process_current->regs, ret); \
+	return 0; \
 } while (0)
 
 _Noreturn void _syscall_exit(int ret) {
@@ -29,7 +31,7 @@ int _syscall_await(void) {
 	{
 		if (iter->noreap) continue;
 		has_children = true;
-		if (iter->state == PS_DEAD) // TODO this path crashes
+		if (iter->state == PS_DEAD) // TODO this path used to crash, still untested
 			SYSCALL_RETURN(process_try2collect(iter));
 	}
 
@@ -272,7 +274,8 @@ void __user *_syscall_memflag(void __user *addr, size_t len, int flags) {
 
 	if (flags & MEMFLAG_FINDFREE) {
 		addr = pagedir_findfree(pages, addr, len);
-		if (!(flags & MEMFLAG_PRESENT)) goto ret;
+		if (!(flags & MEMFLAG_PRESENT))
+			SYSCALL_RETURN((uintptr_t)addr);
 	}
 
 
@@ -296,11 +299,7 @@ void __user *_syscall_memflag(void __user *addr, size_t len, int flags) {
 			pagedir_map(pages, iter, phys, true, true);
 		}
 	}
-
-ret: // the macro is too stupid to handle returning pointers
-	assert(process_current->state == PS_RUNNING); // TODO move to regs_savereturn
-	regs_savereturn(&process_current->regs, (uintptr_t)addr);
-	return addr;
+	SYSCALL_RETURN((uintptr_t)addr);
 }
 
 handle_t _syscall_pipe(int flags) {
-- 
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