power_play/src/arena.c

#include "arena.h"
#include "sys.h"
#include "memory.h"
#include "string.h"
#include "atomic.h"
#include "gstat.h"

/* NOTE: Application will exit if arena fails to reserve or commit initial memory. */
struct arena *arena_alloc(u64 reserve)
{
    //__prof;
    reserve += ARENA_HEADER_SIZE;

    /* Round up to nearest block size */
    u64 block_remainder = reserve % ARENA_BLOCK_SIZE;
    if (block_remainder > 0) {
        reserve += ARENA_BLOCK_SIZE - block_remainder;
    }

    u8 *base = sys_memory_reserve(reserve);
    if (!base) {
        /* Hard fail on memory reserve failure for now */
        sys_panic(LIT("Failed to reserve memory"));
    }
    u64 reserved = reserve;
    gstat_add(GSTAT_MEMORY_RESERVED, reserve);

    /* Commit initial block */
    base = sys_memory_commit(base, ARENA_BLOCK_SIZE);
    if (!base) {
        /* Hard fail on commit failure */
        sys_panic(LIT("Failed to commit initial memory block: System may be out of memory"));
    }

    ASSERT(((u64)base & 0xFFF) == 0);  /* Base should be 4k aligned */
    STATIC_ASSERT(ARENA_HEADER_SIZE <= ARENA_BLOCK_SIZE);  /* Header must fit in first block */
    STATIC_ASSERT(sizeof(struct arena) <= ARENA_HEADER_SIZE);  /* Arena struct must fit in header */

    __profalloc(base, ARENA_BLOCK_SIZE);
    ASAN_POISON(base + sizeof(struct arena), ARENA_BLOCK_SIZE - sizeof(struct arena));
    gstat_add(GSTAT_MEMORY_COMMITTED, ARENA_BLOCK_SIZE);
    gstat_add(GSTAT_NUM_ARENAS, 1);

    /* Create & return arena header at beginning of block */
    struct arena *arena = (struct arena *)base;
    MEMZERO_STRUCT(arena);
    arena->committed = ARENA_BLOCK_SIZE - ARENA_HEADER_SIZE;
    arena->reserved = reserved;
    return arena;
}

void arena_release(struct arena *arena)
{
    ASAN_UNPOISON(arena, arena->committed + ARENA_HEADER_SIZE);
    __prof;
    __proffree(arena);
    gstat_sub(GSTAT_MEMORY_COMMITTED, arena->committed + ARENA_HEADER_SIZE);
    gstat_sub(GSTAT_MEMORY_RESERVED, arena->reserved);
    gstat_sub(GSTAT_NUM_ARENAS, 1);
    sys_memory_release(arena);
}

/* NOTE: Application will exit if arena fails to commit memory */
void *arena_push_bytes_no_zero(struct arena *arena, u64 size, u64 align)
{
    ASSERT(align > 0);
    ASSERT(!arena->readonly);

    void *ptr = NULL;
    u8 *base = arena_base(arena);

    /* Check to avoid aligning when size = 0 */
    if (size > 0) {
        u64 aligned_start_pos = (arena->pos + (align - 1));
        aligned_start_pos -= aligned_start_pos % align;

        u64 new_pos = aligned_start_pos + size;
        if (new_pos > arena->committed) {
            __profn("Arena commit");
            /* Commit new block(s) */
            u64 blocks_needed = (new_pos - arena->committed + ARENA_BLOCK_SIZE - 1) / ARENA_BLOCK_SIZE;
            u64 commit_bytes = blocks_needed * ARENA_BLOCK_SIZE;
            u64 new_capacity = arena->committed + commit_bytes;
            if (new_capacity > arena->reserved) {
                /* Hard fail if we overflow reserved memory for now */
                sys_panic(LIT("Failed to commit new memory block: Overflow of reserved memory"));
            }
            void *commit_address = base + arena->committed;
            if (!sys_memory_commit(commit_address, commit_bytes)) {
                /* Hard fail on memory allocation failure for now */
                sys_panic(LIT("Failed to commit new memory block: System may be out of memory"));
            }
            arena->committed += commit_bytes;
            gstat_add(GSTAT_MEMORY_COMMITTED, commit_bytes);
            __proffree(arena);
            __profalloc(arena, arena->committed + ARENA_HEADER_SIZE);
            ASAN_POISON(commit_address, commit_bytes);
        }

        ptr = base + aligned_start_pos;
        ASAN_UNPOISON(ptr, new_pos - aligned_start_pos);
        arena->pos = new_pos;
    } else {
        ptr = base + arena->pos;
    }

    return ptr;
}

/* Copies the memory from the source arena into the destination arena,
 * replacing old contents. Destination arena will be expanded if necessary. */
void arena_copy_replace(struct arena *dst, struct arena *src)
{
    arena_reset(dst);
    u64 data_size = src->pos;
    u8 *data_src = arena_base(src);
    u8 *data_dst = arena_push_bytes_no_zero(dst, data_size, 1);
    MEMCPY(data_dst, data_src, data_size);
}

void arena_decommit_unused_blocks(struct arena *arena)
{
    /* Not implemented */
    ASSERT(false);
    (UNUSED)arena;
}

void arena_set_readonly(struct arena *arena)
{
#if RTC
    arena->readonly = true;
#endif
    sys_memory_set_committed_readonly(arena, arena->committed + ARENA_HEADER_SIZE);
}

void arena_set_readwrite(struct arena *arena)
{
    sys_memory_set_committed_readwrite(arena, arena->committed + ARENA_HEADER_SIZE);
#if RTC
    arena->readonly = false;
#endif
}