ladybird/Kernel/Heap/kmalloc.cpp
Andreas Kling c1f74bf327 Kernel: Never validate access to the kmalloc memory range
Memory validation is used to verify that user syscalls are allowed to
access a given memory range. Ring 0 threads never make syscalls, and
so will never end up in validation anyway.

The reason we were allowing kmalloc memory accesses is because kernel
thread stacks used to be allocated in kmalloc memory. Since that's no
longer the case, we can stop making exceptions for kmalloc in the
validation code.
2020-01-27 12:43:21 +01:00

234 lines
6.7 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/*
* Really really *really* Q&D malloc() and free() implementations
* just to get going. Don't ever let anyone see this shit. :^)
*/
#include <AK/Assertions.h>
#include <AK/Types.h>
#include <Kernel/Arch/i386/CPU.h>
#include <Kernel/KSyms.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/StdLib.h>
#include <Kernel/Heap/kmalloc.h>
#define SANITIZE_KMALLOC
struct [[gnu::packed]] allocation_t
{
size_t start;
size_t nchunk;
};
#define BASE_PHYSICAL (0xc0000000 + (4 * MB))
#define CHUNK_SIZE 8
#define POOL_SIZE (3 * MB)
#define ETERNAL_BASE_PHYSICAL (0xc0000000 + (2 * MB))
#define ETERNAL_RANGE_SIZE (2 * MB)
static u8 alloc_map[POOL_SIZE / CHUNK_SIZE / 8];
volatile size_t sum_alloc = 0;
volatile size_t sum_free = POOL_SIZE;
volatile size_t kmalloc_sum_eternal = 0;
u32 g_kmalloc_call_count;
u32 g_kfree_call_count;
bool g_dump_kmalloc_stacks;
static u8* s_next_eternal_ptr;
static u8* s_end_of_eternal_range;
void kmalloc_init()
{
memset(&alloc_map, 0, sizeof(alloc_map));
memset((void*)BASE_PHYSICAL, 0, POOL_SIZE);
kmalloc_sum_eternal = 0;
sum_alloc = 0;
sum_free = POOL_SIZE;
s_next_eternal_ptr = (u8*)ETERNAL_BASE_PHYSICAL;
s_end_of_eternal_range = s_next_eternal_ptr + ETERNAL_RANGE_SIZE;
}
void* kmalloc_eternal(size_t size)
{
void* ptr = s_next_eternal_ptr;
s_next_eternal_ptr += size;
ASSERT(s_next_eternal_ptr < s_end_of_eternal_range);
kmalloc_sum_eternal += size;
return ptr;
}
void* kmalloc_aligned(size_t size, size_t alignment)
{
void* ptr = kmalloc(size + alignment + sizeof(void*));
size_t max_addr = (size_t)ptr + alignment;
void* aligned_ptr = (void*)(max_addr - (max_addr % alignment));
((void**)aligned_ptr)[-1] = ptr;
return aligned_ptr;
}
void kfree_aligned(void* ptr)
{
kfree(((void**)ptr)[-1]);
}
void* kmalloc_page_aligned(size_t size)
{
void* ptr = kmalloc_aligned(size, PAGE_SIZE);
size_t d = (size_t)ptr;
ASSERT((d & PAGE_MASK) == d);
return ptr;
}
void* kmalloc_impl(size_t size)
{
InterruptDisabler disabler;
++g_kmalloc_call_count;
if (g_dump_kmalloc_stacks && ksyms_ready) {
dbgprintf("kmalloc(%u)\n", size);
dump_backtrace();
}
// We need space for the allocation_t structure at the head of the block.
size_t real_size = size + sizeof(allocation_t);
if (sum_free < real_size) {
dump_backtrace();
kprintf("%s(%u) kmalloc(): PANIC! Out of memory (sucks, dude)\nsum_free=%u, real_size=%u\n", current->process().name().characters(), current->pid(), sum_free, real_size);
hang();
}
size_t chunks_needed = real_size / CHUNK_SIZE;
if (real_size % CHUNK_SIZE)
++chunks_needed;
size_t chunks_here = 0;
size_t first_chunk = 0;
for (size_t i = 0; i < (POOL_SIZE / CHUNK_SIZE / 8); ++i) {
if (alloc_map[i] == 0xff) {
// Skip over completely full bucket.
chunks_here = 0;
continue;
}
// FIXME: This scan can be optimized further with LZCNT.
for (size_t j = 0; j < 8; ++j) {
if (!(alloc_map[i] & (1 << j))) {
if (chunks_here == 0) {
// Mark where potential allocation starts.
first_chunk = i * 8 + j;
}
++chunks_here;
if (chunks_here == chunks_needed) {
auto* a = (allocation_t*)(BASE_PHYSICAL + (first_chunk * CHUNK_SIZE));
u8* ptr = (u8*)a;
ptr += sizeof(allocation_t);
a->nchunk = chunks_needed;
a->start = first_chunk;
for (size_t k = first_chunk; k < (first_chunk + chunks_needed); ++k) {
alloc_map[k / 8] |= 1 << (k % 8);
}
sum_alloc += a->nchunk * CHUNK_SIZE;
sum_free -= a->nchunk * CHUNK_SIZE;
#ifdef SANITIZE_KMALLOC
memset(ptr, 0xbb, (a->nchunk * CHUNK_SIZE) - sizeof(allocation_t));
#endif
return ptr;
}
} else {
// This is in use, so restart chunks_here counter.
chunks_here = 0;
}
}
}
kprintf("%s(%u) kmalloc(): PANIC! Out of memory (no suitable block for size %u)\n", current->process().name().characters(), current->pid(), size);
dump_backtrace();
hang();
}
void kfree(void* ptr)
{
if (!ptr)
return;
InterruptDisabler disabler;
++g_kfree_call_count;
auto* a = (allocation_t*)((((u8*)ptr) - sizeof(allocation_t)));
for (size_t k = a->start; k < (a->start + a->nchunk); ++k)
alloc_map[k / 8] &= ~(1 << (k % 8));
sum_alloc -= a->nchunk * CHUNK_SIZE;
sum_free += a->nchunk * CHUNK_SIZE;
#ifdef SANITIZE_KMALLOC
memset(a, 0xaa, a->nchunk * CHUNK_SIZE);
#endif
}
void* krealloc(void* ptr, size_t new_size)
{
if (!ptr)
return kmalloc(new_size);
InterruptDisabler disabler;
auto* a = (allocation_t*)((((u8*)ptr) - sizeof(allocation_t)));
size_t old_size = a->nchunk * CHUNK_SIZE;
if (old_size == new_size)
return ptr;
auto* new_ptr = kmalloc(new_size);
memcpy(new_ptr, ptr, min(old_size, new_size));
kfree(ptr);
return new_ptr;
}
void* operator new(size_t size)
{
return kmalloc(size);
}
void* operator new[](size_t size)
{
return kmalloc(size);
}