The detect_memory_region() has been broken on 6.6 kernel[1]. This patch fixes it by: 1. Do not use memcmp() on unallocated memory, as the new introduced fortify dynamic object size check[2] will return unexpected result. 2. Use a fixed pattern instead of a random function pointer as the magic value. 3. Flip magic value and double check it. 4. Enable this feature only for 32-bit CPUs. Currently, only ath79 and ralink CPUs are using it. And 64-bit CPU doesn't have the KSEG1ADDR definition. [1] https://github.com/openwrt/openwrt/pull/14774#issuecomment-1989356746 [2] commit 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when available") Signed-off-by: Shiji Yang <yangshiji66@xxxxxxxxxxx> Tested-by: Mieczyslaw Nalewaj <namiltd@xxxxxxxxx> --- arch/mips/include/asm/bootinfo.h | 2 ++ arch/mips/kernel/setup.c | 17 ++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-) diff --git a/arch/mips/include/asm/bootinfo.h b/arch/mips/include/asm/bootinfo.h index 2128ba903391..8516c11916a4 100644 --- a/arch/mips/include/asm/bootinfo.h +++ b/arch/mips/include/asm/bootinfo.h @@ -93,7 +93,9 @@ const char *get_system_type(void); extern unsigned long mips_machtype; +#ifndef CONFIG_64BIT extern void detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_addr_t sz_max); +#endif extern void prom_init(void); extern void prom_free_prom_memory(void); diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c index 12a1a4ffb602..3a3bc1b7e62e 100644 --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -86,21 +86,27 @@ static struct resource bss_resource = { .name = "Kernel bss", }; unsigned long __kaslr_offset __ro_after_init; EXPORT_SYMBOL(__kaslr_offset); -static void *detect_magic __initdata = detect_memory_region; - #ifdef CONFIG_MIPS_AUTO_PFN_OFFSET unsigned long ARCH_PFN_OFFSET; EXPORT_SYMBOL(ARCH_PFN_OFFSET); #endif +#ifndef CONFIG_64BIT +static u32 detect_magic __initdata; +#define MIPS_MEM_TEST_PATTERN 0xaa5555aa + void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_addr_t sz_max) { - void *dm = &detect_magic; + void *dm = (void *)KSEG1ADDR(&detect_magic); phys_addr_t size; for (size = sz_min; size < sz_max; size <<= 1) { - if (!memcmp(dm, dm + size, sizeof(detect_magic))) - break; + __raw_writel(MIPS_MEM_TEST_PATTERN, dm); + if (__raw_readl(dm) == __raw_readl(dm + size)) { + __raw_writel(~MIPS_MEM_TEST_PATTERN, dm); + if (__raw_readl(dm) == __raw_readl(dm + size)) + break; + } } pr_debug("Memory: %lluMB of RAM detected at 0x%llx (min: %lluMB, max: %lluMB)\n", @@ -111,6 +117,7 @@ void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_add memblock_add(start, size); } +#endif /* CONFIG_64BIT */ /* * Manage initrd -- 2.45.1
