x86 setup: sizeof() is unsigned, unbreak comparisons

We use signed values for limit checking since the values can go
negative under certain circumstances.  However, sizeof() is unsigned
and forces the comparison to be unsigned, so move the comparison into
the heap_free() macros so we can ensure it is a signed comparison.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>

4 files changed, 5 insertions, 5 deletions

diff --git a/arch/x86/boot/boot.h b/arch/x86/boot/boot.h
index 887874f4b4..d2b5adf465 100644
--- a/arch/x86/boot/boot.h
+++ b/arch/x86/boot/boot.h
@@ -216,9 +216,9 @@ static inline char *__get_heap(size_t s, size_t a, size_t n)
 #define GET_HEAP(type, n) \
         ((type *)__get_heap(sizeof(type),__alignof__(type),(n)))
 
-static inline int heap_free(void)
+static inline bool heap_free(size_t n)
 {
-        return heap_end-HEAP;
+        return (int)(heap_end-HEAP) >= (int)n;
 }
 
 /* copy.S */
diff --git a/arch/x86/boot/video-bios.c b/arch/x86/boot/video-bios.c
index 68e65d95cd..ed0672a818 100644
--- a/arch/x86/boot/video-bios.c
+++ b/arch/x86/boot/video-bios.c
@@ -79,7 +79,7 @@ static int bios_probe(void)
         video_bios.modes = GET_HEAP(struct mode_info, 0);
 
         for (mode = 0x14; mode <= 0x7f; mode++) {
-                if (heap_free() < sizeof(struct mode_info))
+                if (!heap_free(sizeof(struct mode_info)))
                         break;
 
                 if (mode_defined(VIDEO_FIRST_BIOS+mode))
diff --git a/arch/x86/boot/video-vesa.c b/arch/x86/boot/video-vesa.c
index 1921907107..4716b9a963 100644
--- a/arch/x86/boot/video-vesa.c
+++ b/arch/x86/boot/video-vesa.c
@@ -57,7 +57,7 @@ static int vesa_probe(void)
         while ((mode = rdfs16(mode_ptr)) != 0xffff) {
                 mode_ptr += 2;
 
-                if (heap_free() < sizeof(struct mode_info))
+                if (!heap_free(sizeof(struct mode_info)))
                         break;  /* Heap full, can't save mode info */
 
                 if (mode & ~0x1ff)
diff --git a/arch/x86/boot/video.c b/arch/x86/boot/video.c
index e4ba897bf9..ad9712f017 100644
--- a/arch/x86/boot/video.c
+++ b/arch/x86/boot/video.c
@@ -371,7 +371,7 @@ static void save_screen(void)
         saved.curx = boot_params.screen_info.orig_x;
         saved.cury = boot_params.screen_info.orig_y;
 
-        if (heap_free() < saved.x*saved.y*sizeof(u16)+512)
+        if (!heap_free(saved.x*saved.y*sizeof(u16)+512))
                 return;         /* Not enough heap to save the screen */
 
         saved.data = GET_HEAP(u16, saved.x*saved.y);