generic: MIPS64: fix detect_memory_region() compilation error

1. Enable this feature only for 32-bit CPUs as MIPS64 can not
   access the full range unmapped uncached memory.

2. Backport this fix to the 6.1 old LTS kernel.

Signed-off-by: Shiji Yang <yangshiji66@qq.com>

target/linux/generic/pending-6.1/350-mips-kernel-fix-detect_memory_region-function.patch

@@ -0,0 +1,74 @@
+From: Shiji Yang <yangshiji66@outlook.com>
+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.
+4. Enable this feature only for 32-bit CPUs. Currently, only ath79 and
+   ralink CPUs are using it.
+
+[1] 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when available")
+Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
+---
+ arch/mips/include/asm/bootinfo.h |  2 ++
+ arch/mips/kernel/setup.c         | 17 ++++++++++++-----
+ 2 files changed, 14 insertions(+), 5 deletions(-)
+
+--- 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);
+--- a/arch/mips/kernel/setup.c
++++ b/arch/mips/kernel/setup.c
+@@ -90,21 +90,27 @@ static struct resource bss_resource = {
+ 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",
+@@ -115,6 +121,7 @@ void __init detect_memory_region(phys_ad
+ 
+ 	memblock_add(start, size);
+ }
++#endif /* CONFIG_64BIT */
+ 
+ /*
+  * Manage initrd

target/linux/generic/pending-6.6/350-mips-kernel-fix-detect_memory_region-function.patch

@@ -7,35 +7,45 @@ Subject: [PATCH] mips: kernel: fix detect_memory_region() function
 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.
 
 [1] 439a1bcac648 ("fortify: Use __builtin_dynamic_object_size() when available")
 Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
 ---
- arch/mips/kernel/setup.c | 16 +++++++++++-----
+ arch/mips/include/asm/bootinfo.h |  2 ++
- 1 file changed, 11 insertions(+), 5 deletions(-)
+ arch/mips/kernel/setup.c         | 17 ++++++++++++-----
+ 2 files changed, 14 insertions(+), 5 deletions(-)
 
+--- 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);
 --- a/arch/mips/kernel/setup.c
 +++ b/arch/mips/kernel/setup.c
-@@ -46,6 +46,8 @@
+@@ -90,21 +90,27 @@ static struct resource bss_resource = {
- #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);
+ 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;
@@ -54,3 +64,11 @@ Signed-off-by: Shiji Yang <yangshiji66@outlook.com>
  	}
  
  	pr_debug("Memory: %lluMB of RAM detected at 0x%llx (min: %lluMB, max: %lluMB)\n",
+@@ -115,6 +121,7 @@ void __init detect_memory_region(phys_ad
+ 
+ 	memblock_add(start, size);
+ }
++#endif /* CONFIG_64BIT */
+ 
+ /*
+  * Manage initrd

target/linux/ramips/patches-6.1/314-MIPS-add-bootargs-override-property.patch

@@ -17,7 +17,7 @@ Signed-off-by: David Bauer <mail@david-bauer.net>
 
 --- a/arch/mips/kernel/setup.c
 +++ b/arch/mips/kernel/setup.c
-@@ -557,8 +557,28 @@ static int __init bootcmdline_scan_chose
+@@ -564,8 +564,28 @@ static int __init bootcmdline_scan_chose
  
  #endif /* CONFIG_OF_EARLY_FLATTREE */
  
@@ -46,7 +46,7 @@ Signed-off-by: David Bauer <mail@david-bauer.net>
  	bool dt_bootargs = false;
  
  	/*
-@@ -572,6 +592,14 @@ static void __init bootcmdline_init(void
+@@ -579,6 +599,14 @@ static void __init bootcmdline_init(void
  	}
  
  	/*

target/linux/ramips/patches-6.1/315-owrt-hack-fix-mt7688-cache-issue.patch

@@ -10,7 +10,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 
 --- a/arch/mips/kernel/setup.c
 +++ b/arch/mips/kernel/setup.c
-@@ -699,7 +699,6 @@ static void __init arch_mem_init(char **
+@@ -706,7 +706,6 @@ static void __init arch_mem_init(char **
  	mips_reserve_vmcore();
  
  	mips_parse_crashkernel();
@@ -18,7 +18,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
  
  	/*
  	 * In order to reduce the possibility of kernel panic when failed to
-@@ -834,6 +833,7 @@ void __init setup_arch(char **cmdline_p)
+@@ -841,6 +840,7 @@ void __init setup_arch(char **cmdline_p)
  
  	cpu_cache_init();
  	paging_init();

target/linux/ramips/patches-6.6/314-MIPS-add-bootargs-override-property.patch

@@ -17,7 +17,7 @@ Signed-off-by: David Bauer <mail@david-bauer.net>
 
 --- a/arch/mips/kernel/setup.c
 +++ b/arch/mips/kernel/setup.c
-@@ -563,8 +563,28 @@ static int __init bootcmdline_scan_chose
+@@ -564,8 +564,28 @@ static int __init bootcmdline_scan_chose
  
  #endif /* CONFIG_OF_EARLY_FLATTREE */
  
@@ -46,7 +46,7 @@ Signed-off-by: David Bauer <mail@david-bauer.net>
  	bool dt_bootargs = false;
  
  	/*
-@@ -578,6 +598,14 @@ static void __init bootcmdline_init(void
+@@ -579,6 +599,14 @@ static void __init bootcmdline_init(void
  	}
  
  	/*

target/linux/ramips/patches-6.6/315-owrt-hack-fix-mt7688-cache-issue.patch

@@ -10,7 +10,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 
 --- a/arch/mips/kernel/setup.c
 +++ b/arch/mips/kernel/setup.c
-@@ -705,7 +705,6 @@ static void __init arch_mem_init(char **
+@@ -706,7 +706,6 @@ static void __init arch_mem_init(char **
  	mips_reserve_vmcore();
  
  	mips_parse_crashkernel();
@@ -18,7 +18,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
  
  	/*
  	 * In order to reduce the possibility of kernel panic when failed to
-@@ -841,6 +840,7 @@ void __init setup_arch(char **cmdline_p)
+@@ -842,6 +841,7 @@ void __init setup_arch(char **cmdline_p)
  
  	cpu_cache_init();
  	paging_init();