From: Shiji Yang Date: Wed, 13 Mar 2024 20:28:37 +0800 Subject: [PATCH] mips: kernel: fix detect_memory_region() function 1. Do not use memcmp() on unallocated memory, as the new introduced fortify dynamic object size check[1] will report 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. [1] 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when available") Signed-off-by: Shiji Yang disabling fix for CONFIG_CPU_MIPS64 Signed-off-by: Mieczyslaw Nalewaj --- arch/mips/kernel/setup.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletions(-) --- a/arch/mips/kernel/setup.c +++ b/arch/mips/kernel/setup.c @@ -90,7 +90,12 @@ unsigned long __kaslr_offset __ro_after_init; EXPORT_SYMBOL(__kaslr_offset); +#ifdef CONFIG_CPU_MIPS64 static void *detect_magic __initdata = detect_memory_region; +#else +static u32 detect_magic __initdata; +#define MIPS_MEM_TEST_PATTERN 0xaa5555aa +#endif #ifdef CONFIG_MIPS_AUTO_PFN_OFFSET unsigned long ARCH_PFN_OFFSET; @@ -99,13 +104,26 @@ void __init detect_memory_region(phys_addr_t start, phys_addr_t sz_min, phys_addr_t sz_max) { - void *dm = &detect_magic; phys_addr_t size; +#ifdef CONFIG_CPU_MIPS64 + void *dm = &detect_magic; for (size = sz_min; size < sz_max; size <<= 1) { if (!memcmp(dm, dm + size, sizeof(detect_magic))) break; } +#else + void* dm = (void *)KSEG1ADDR(&detect_magic); + + for (size = sz_min; size < sz_max; size <<= 1) { + __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; + } + } +#endif pr_debug("Memory: %lluMB of RAM detected at 0x%llx (min: %lluMB, max: %lluMB)\n", ((unsigned long long) size) / SZ_1M,