kernel/arch/powerpc/include/asm/kasan.h, branch linux-6.2.y

powerpc/64e: KASAN Full support for BOOK3E/64

2022-06-29T07:04:15Z

We now have memory organised in a way that allows implementing KASAN. Unlike book3s/64, book3e always has translation active so the only thing needed to use KASAN is to setup an early zero shadow mapping just after setting a stack pointer and before calling early_setup(). The memory layout is now as follows +------------------------+ Kernel virtual map end (0xc000200000000000) | | | 16TB of KASAN map | | | +------------------------+ Kernel KASAN shadow map start | | | 16TB of IO map | | | +------------------------+ Kernel IO map start | | | 16TB of vmemmap | | | +------------------------+ Kernel vmemmap start | | | 16TB of vmap | | | +------------------------+ Kernel virt start (0xc000100000000000) | | | 64TB of linear mem | | | +------------------------+ Kernel linear (0xc.....) Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/0bef8beda27baf71e3b9e8b13e620fba6e19499b.1656427701.git.christophe.leroy@csgroup.eu

powerpc: Book3S 64-bit outline-only KASAN support

2022-05-22T05:58:29Z

Implement a limited form of KASAN for Book3S 64-bit machines running under the Radix MMU, supporting only outline mode. - Enable the compiler instrumentation to check addresses and maintain the shadow region. (This is the guts of KASAN which we can easily reuse.) - Require kasan-vmalloc support to handle modules and anything else in vmalloc space. - KASAN needs to be able to validate all pointer accesses, but we can't instrument all kernel addresses - only linear map and vmalloc. On boot, set up a single page of read-only shadow that marks all iomap and vmemmap accesses as valid. - Document KASAN in powerpc docs. Background ---------- KASAN support on Book3S is a bit tricky to get right: - It would be good to support inline instrumentation so as to be able to catch stack issues that cannot be caught with outline mode. - Inline instrumentation requires a fixed offset. - Book3S runs code with translations off ("real mode") during boot, including a lot of generic device-tree parsing code which is used to determine MMU features. [ppc64 mm note: The kernel installs a linear mapping at effective address c000...-c008.... This is a one-to-one mapping with physical memory from 0000... onward. Because of how memory accesses work on powerpc 64-bit Book3S, a kernel pointer in the linear map accesses the same memory both with translations on (accessing as an 'effective address'), and with translations off (accessing as a 'real address'). This works in both guests and the hypervisor. For more details, see s5.7 of Book III of version 3 of the ISA, in particular the Storage Control Overview, s5.7.3, and s5.7.5 - noting that this KASAN implementation currently only supports Radix.] - Some code - most notably a lot of KVM code - also runs with translations off after boot. - Therefore any offset has to point to memory that is valid with translations on or off. One approach is just to give up on inline instrumentation. This way boot-time checks can be delayed until after the MMU is set is up, and we can just not instrument any code that runs with translations off after booting. Take this approach for now and require outline instrumentation. Previous attempts allowed inline instrumentation. However, they came with some unfortunate restrictions: only physically contiguous memory could be used and it had to be specified at compile time. Maybe we can do better in the future. [paulus@ozlabs.org - Rebased onto 5.17. Note that a kernel with CONFIG_KASAN=y will crash during boot on a machine using HPT translation because not all the entry points to the generic KASAN code are protected with a call to kasan_arch_is_ready().] Originally-by: Balbir Singh # ppc64 out-of-line radix version Signed-off-by: Daniel Axtens Signed-off-by: Paul Mackerras [mpe: Update copyright year and comment formatting] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/YoTE69OQwiG7z+Gu@cleo

powerpc/kasan: Fix shadow start address with modules

2021-04-25T11:29:04Z

Modules are now located before kernel, KASAN area has to be extended accordingly. Fixes: 80edc68e0479 ("powerpc/32s: Define a MODULE area below kernel text all the time") Fixes: 9132a2e82adc ("powerpc/8xx: Define a MODULE area below kernel text") Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c68163065163f303f5af1e4bbdd9f1ce69f0543e.1619260465.git.christophe.leroy@csgroup.eu

powerpc/kasan: Fix KASAN_SHADOW_START on BOOK3S_32

2020-08-18T03:39:52Z

On BOOK3S_32, when we have modules and strict kernel RWX, modules are not in vmalloc space but in a dedicated segment that is below PAGE_OFFSET. So KASAN_SHADOW_START must take it into account. MODULES_VADDR can't be used because it is not defined yet in kasan.h Fixes: 6ca055322da8 ("powerpc/32s: Use dedicated segment for modules with STRICT_KERNEL_RWX") Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/6eddca2d5611fd57312a88eae31278c87a8fc99d.1596641224.git.christophe.leroy@csgroup.eu

Revert "powerpc/kasan: Fix shadow pages allocation failure"

2020-07-15T02:04:39Z

This reverts commit d2a91cef9bbdeb87b7449fdab1a6be6000930210. This commit moved too much work in kasan_init(). The allocation of shadow pages has to be moved for the reason explained in that patch, but the allocation of page tables still need to be done before switching to the final hash table. First revert the incorrect commit, following patch redoes it properly. Fixes: d2a91cef9bbd ("powerpc/kasan: Fix shadow pages allocation failure") Cc: stable@vger.kernel.org Reported-by: Erhard F. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://bugzilla.kernel.org/show_bug.cgi?id=208181 Link: https://lore.kernel.org/r/3667deb0911affbf999b99f87c31c77d5e870cd2.1593690707.git.christophe.leroy@csgroup.eu

powerpc/32s: Implement dedicated kasan_init_region()

2020-05-26T12:22:23Z

Implement a kasan_init_region() dedicated to book3s/32 that allocates KASAN regions using BATs. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/709e821602b48a1d7c211a9b156da26db98c3e9d.1589866984.git.christophe.leroy@csgroup.eu

powerpc/kasan: Declare kasan_init_region() weak

2020-05-20T13:41:03Z

In order to alloc sub-arches to alloc KASAN regions using optimised methods (Huge pages on 8xx, BATs on BOOK3S, ...), declare kasan_init_region() weak. Also make kasan_init_shadow_page_tables() accessible from outside, so that it can be called from the specific kasan_init_region() functions if needed. And populate remaining KASAN address space only once performed the region mapping, to allow 8xx to allocate hugepd instead of standard page tables for mapping via 8M hugepages. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/3c1ce419fa1b5a4171b92d7fb16455ca17e1b96d.1589866984.git.christophe.leroy@csgroup.eu

powerpc/kasan: Fix shadow pages allocation failure

2020-05-20T13:41:02Z

Doing kasan pages allocation in MMU_init is too early, kernel doesn't have access yet to the entire memory space and memblock_alloc() fails when the kernel is a bit big. Do it from kasan_init() instead. Fixes: 2edb16efc899 ("powerpc/32: Add KASAN support") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/c24163ee5d5f8cdf52fefa45055ceb35435b8f15.1589866984.git.christophe.leroy@csgroup.eu

powerpc/kasan: Fix issues by lowering KASAN_SHADOW_END

2020-05-20T13:41:01Z

At the time being, KASAN_SHADOW_END is 0x100000000, which is 0 in 32 bits representation. This leads to a couple of issues: - kasan_remap_early_shadow_ro() does nothing because the comparison k_cur < k_end is always false. - In ptdump, address comparison for markers display fails and the marker's name is printed at the start of the KASAN area instead of being printed at the end. However, there is no need to shadow the KASAN shadow area itself, so the KASAN shadow area can stop shadowing memory at the start of itself. With a PAGE_OFFSET set to 0xc0000000, KASAN shadow area is then going from 0xf8000000 to 0xff000000. Fixes: cbd18991e24f ("powerpc/mm: Fix an Oops in kasan_mmu_init()") Cc: stable@vger.kernel.org Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/ae1a3c0d19a37410c209c3fc453634cfcc0ee318.1589866984.git.christophe.leroy@csgroup.eu

powerpc/32: Add support of KASAN_VMALLOC

2020-01-27T11:37:33Z

Add support of KASAN_VMALLOC on PPC32. To allow this, the early shadow covering the VMALLOC space need to be removed once high_memory var is set and before freeing memblock. And the VMALLOC area need to be aligned such that boundaries are covered by a full shadow page. Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/031dec5487bde9b2181c8b3c9800e1879cf98c1a.1579024426.git.christophe.leroy@c-s.fr