diff options
| -rw-r--r-- | src/arch/generic.h | 1 | ||||
| -rw-r--r-- | src/kernel/main.c | 2 | ||||
| -rw-r--r-- | src/kernel/mem.c | 15 | ||||
| -rw-r--r-- | src/kernel/mem.h | 3 |
4 files changed, 16 insertions, 5 deletions
diff --git a/src/arch/generic.h b/src/arch/generic.h index f9617ab..4bed2fe 100644 --- a/src/arch/generic.h +++ b/src/arch/generic.h @@ -3,6 +3,7 @@ #include <arch/log.h> // i have no idea where else to put it +// some code assumes that it's a power of 2 #define PAGE_SIZE 4096 // src/arch/i386/boot.s diff --git a/src/kernel/main.c b/src/kernel/main.c index d2f2e7f..761e499 100644 --- a/src/kernel/main.c +++ b/src/kernel/main.c @@ -9,7 +9,7 @@ void r3_test(); void kmain(struct kmain_info info) { log_write(info.init.at, info.init.size); log_const("mem..."); - mem_init(); + mem_init(&info); log_const("creating process..."); struct process *proc = process_new(r3_test); diff --git a/src/kernel/mem.c b/src/kernel/mem.c index d002050..b455b25 100644 --- a/src/kernel/mem.c +++ b/src/kernel/mem.c @@ -1,11 +1,20 @@ #include <arch/generic.h> #include <kernel/mem.h> +#include <stdint.h> -extern void *_bss_end; static void *highest_page; -void mem_init() { - highest_page = &_bss_end; +void mem_init(struct kmain_info *info) { + // finds the highest used page, and starts allocating pages above it + extern char _bss_end; + void *highest = &_bss_end; + size_t page_mask = PAGE_SIZE - 1; + + if (highest < info->init.at + info->init.size) + highest = info->init.at + info->init.size; + + // align up to PAGE_SIZE + highest_page = (void*)(((uintptr_t)highest + page_mask) & ~page_mask); } void *page_alloc(size_t pages) { diff --git a/src/kernel/mem.h b/src/kernel/mem.h index efa65d6..f608bb8 100644 --- a/src/kernel/mem.h +++ b/src/kernel/mem.h @@ -1,7 +1,8 @@ #pragma once +#include <kernel/main.h> #include <stddef.h> -void mem_init(); +void mem_init(struct kmain_info *); // allocates `pages` consecutive pages void *page_alloc(size_t pages); |