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- From: Shiji Yang <[email protected]>
- 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 <[email protected]>
- ---
- arch/mips/kernel/setup.c | 16 +++++++++++-----
- 1 file changed, 11 insertions(+), 5 deletions(-)
- --- a/arch/mips/kernel/setup.c
- +++ b/arch/mips/kernel/setup.c
- @@ -46,6 +46,8 @@
- #include <asm/prom.h>
- #include <asm/fw/fw.h>
-
- +#define MIPS_MEM_TEST_PATTERN 0xaa5555aa
- +
- #ifdef CONFIG_MIPS_ELF_APPENDED_DTB
- char __section(".appended_dtb") __appended_dtb[0x100000];
- #endif /* CONFIG_MIPS_ELF_APPENDED_DTB */
- @@ -90,7 +92,7 @@ static struct resource bss_resource = {
- unsigned long __kaslr_offset __ro_after_init;
- EXPORT_SYMBOL(__kaslr_offset);
-
- -static void *detect_magic __initdata = detect_memory_region;
- +static u32 detect_magic __initdata;
-
- #ifdef CONFIG_MIPS_AUTO_PFN_OFFSET
- unsigned long ARCH_PFN_OFFSET;
- @@ -99,12 +101,16 @@ EXPORT_SYMBOL(ARCH_PFN_OFFSET);
-
- 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",
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