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| author | Gerd Bayer <gbayer@linux.ibm.com> | 2026-01-16 18:02:42 +0300 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2026-01-27 14:21:20 +0300 |
| commit | 0d453ba04044bb1b0df366d4a0a9098481f14621 (patch) | |
| tree | 384dd457d59de5df6c9e16d6e317308eb83b0331 | |
| parent | 0875816a58d855d674305a7330c44d25ce27dca2 (diff) | |
| download | linux-0d453ba04044bb1b0df366d4a0a9098481f14621.tar.xz | |
s390/Kconfig: Define non-zero ILLEGAL_POINTER_VALUE
Define CONFIG_ILLEGAL_POINTER_VALUE to the eye-catching non-zero value
of 0xdead000000000000, consistent with other architectures. Assert at
compile-time that the poison pointers that include/linux/poison.h
defines based on this illegal pointer are beyond the largest useful
virtual addresses. Also, assert at compile-time that the range of poison
pointers per include/linux/poison.h (currently a range of less than
0x10000 addresses) does not overlap with the range used for address
handles for s390's non-MIO PCI instructions.
This enables s390 to track the DMA mappings by the network stack's
page_pool that was introduced with [0]. Other functional changes are not
intended.
Other archictectures have introduced this for various other reasons with
commit 5c178472af24 ("riscv: define ILLEGAL_POINTER_VALUE for 64bit")
commit f6853eb561fb ("powerpc/64: Define ILLEGAL_POINTER_VALUE for 64-bit")
commit bf0c4e047324 ("arm64: kconfig: Move LIST_POISON to a safe value")
commit a29815a333c6 ("core, x86: make LIST_POISON less deadly")
[0] https://lore.kernel.org/all/20250409-page-pool-track-dma-v9-0-6a9ef2e0cba8@redhat.com/
Reviewed-by: Niklas Schnelle <schnelle@linux.ibm.com>
Signed-off-by: Gerd Bayer <gbayer@linux.ibm.com>
Acked-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
| -rw-r--r-- | Documentation/arch/s390/mm.rst | 4 | ||||
| -rw-r--r-- | arch/s390/Kconfig | 4 | ||||
| -rw-r--r-- | arch/s390/boot/startup.c | 1 | ||||
| -rw-r--r-- | arch/s390/include/asm/pci_io.h | 1 | ||||
| -rw-r--r-- | arch/s390/pci/pci.c | 2 |
5 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/arch/s390/mm.rst b/Documentation/arch/s390/mm.rst index 084adad5eef9..19681157c6f2 100644 --- a/Documentation/arch/s390/mm.rst +++ b/Documentation/arch/s390/mm.rst @@ -109,3 +109,7 @@ Virtual memory layout | KASAN shadow | KASAN untracked | | +------------------+ ASCE limit + | | + | CONFIG_ILLEGAL_POINTER_VALUE causes memory access fault + | | + +------------------+ diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig index fcce8c5db703..cda697a03abf 100644 --- a/arch/s390/Kconfig +++ b/arch/s390/Kconfig @@ -719,6 +719,10 @@ config ARCH_SPARSEMEM_ENABLE config ARCH_SPARSEMEM_DEFAULT def_bool y +config ILLEGAL_POINTER_VALUE + hex + default 0xdead000000000000 + config MAX_PHYSMEM_BITS int "Maximum size of supported physical memory in bits (42-53)" range 42 53 diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c index f77067dfc2a8..7f3343493ab9 100644 --- a/arch/s390/boot/startup.c +++ b/arch/s390/boot/startup.c @@ -336,6 +336,7 @@ static unsigned long setup_kernel_memory_layout(unsigned long kernel_size) BUILD_BUG_ON(!IS_ALIGNED(TEXT_OFFSET, THREAD_SIZE)); BUILD_BUG_ON(!IS_ALIGNED(__NO_KASLR_START_KERNEL, THREAD_SIZE)); BUILD_BUG_ON(__NO_KASLR_END_KERNEL > _REGION1_SIZE); + BUILD_BUG_ON(CONFIG_ILLEGAL_POINTER_VALUE < _REGION1_SIZE); vsize = get_vmem_size(ident_map_size, vmemmap_size, vmalloc_size, _REGION3_SIZE); boot_debug("vmem size estimated: 0x%016lx\n", vsize); if (IS_ENABLED(CONFIG_KASAN) || __NO_KASLR_END_KERNEL > _REGION2_SIZE || diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h index 43a5ea4ee20f..f3bef5bc7223 100644 --- a/arch/s390/include/asm/pci_io.h +++ b/arch/s390/include/asm/pci_io.h @@ -18,6 +18,7 @@ #define ZPCI_IOMAP_SHIFT 48 #define ZPCI_IOMAP_ADDR_SHIFT 62 #define ZPCI_IOMAP_ADDR_BASE (1UL << ZPCI_IOMAP_ADDR_SHIFT) +#define ZPCI_IOMAP_ADDR_MAX ((1UL << (ZPCI_IOMAP_ADDR_SHIFT + 1)) - 1) #define ZPCI_IOMAP_ADDR_OFF_MASK ((1UL << ZPCI_IOMAP_SHIFT) - 1) #define ZPCI_IOMAP_MAX_ENTRIES \ (1UL << (ZPCI_IOMAP_ADDR_SHIFT - ZPCI_IOMAP_SHIFT)) diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c index 0d952e8fdc8a..97bab20bc163 100644 --- a/arch/s390/pci/pci.c +++ b/arch/s390/pci/pci.c @@ -1065,6 +1065,8 @@ static int zpci_mem_init(void) { BUILD_BUG_ON(!is_power_of_2(__alignof__(struct zpci_fmb)) || __alignof__(struct zpci_fmb) < sizeof(struct zpci_fmb)); + BUILD_BUG_ON((CONFIG_ILLEGAL_POINTER_VALUE + 0x10000 > ZPCI_IOMAP_ADDR_BASE) && + (CONFIG_ILLEGAL_POINTER_VALUE <= ZPCI_IOMAP_ADDR_MAX)); zdev_fmb_cache = kmem_cache_create("PCI_FMB_cache", sizeof(struct zpci_fmb), __alignof__(struct zpci_fmb), 0, NULL); |