diff mbox series

MIPS: relocatable: Provide kaslr_offset() to get the kernel offset

Message ID 1611720745-8256-1-git-send-email-hejinyang@loongson.cn (mailing list archive)
State Superseded
Headers show
Series MIPS: relocatable: Provide kaslr_offset() to get the kernel offset | expand

Commit Message

Jinyang He Jan. 27, 2021, 4:12 a.m. UTC 
Use kimage_vaddr to indicate kernel start address. Provide kaslr_offset()
to get the kernel offset when KASLR is enabled. Error may occur before
update_kimage_vaddr(), so put it at the end of the offset branch.

Fixes: a307a4ce9ecd ("MIPS: Loongson64: Add KASLR support")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
---
 arch/mips/include/asm/page.h |  6 ++++++
 arch/mips/kernel/relocate.c  | 12 ++++++++++++
 arch/mips/kernel/setup.c     |  3 +++
 3 files changed, 21 insertions(+)

Comments

Thomas Bogendoerfer Feb. 1, 2021, 12:50 p.m. UTC | #1 
On Wed, Jan 27, 2021 at 12:12:25PM +0800, Jinyang He wrote:
> Use kimage_vaddr to indicate kernel start address. Provide kaslr_offset()
> to get the kernel offset when KASLR is enabled. Error may occur before
> update_kimage_vaddr(), so put it at the end of the offset branch.
> 
> Fixes: a307a4ce9ecd ("MIPS: Loongson64: Add KASLR support")
> Reported-by: kernel test robot <lkp@intel.com>
> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
> ---
>  arch/mips/include/asm/page.h |  6 ++++++
>  arch/mips/kernel/relocate.c  | 12 ++++++++++++
>  arch/mips/kernel/setup.c     |  3 +++
>  3 files changed, 21 insertions(+)
> 
> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
> index 6a77bc4..9429520 100644
> --- a/arch/mips/include/asm/page.h
> +++ b/arch/mips/include/asm/page.h
> @@ -255,6 +255,12 @@ extern bool __virt_addr_valid(const volatile void *kaddr);
>  
>  #define VM_DATA_DEFAULT_FLAGS	VM_DATA_FLAGS_TSK_EXEC
>  
> +extern unsigned long kimage_vaddr;
> +static inline unsigned long kaslr_offset(void)
> +{
> +	return kimage_vaddr - VMLINUX_LOAD_ADDRESS;
> +}

this breaks for 32bit kernels:

<command-line>:0:22: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
/local/tbogendoerfer/korg/linux/arch/mips/kernel/setup.c:87:41: note: in expansion of macro ‘VMLINUX_LOAD_ADDRESS’
 unsigned long kimage_vaddr __initdata = VMLINUX_LOAD_ADDRESS;
                                         ^~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors
Jinyang He Feb. 2, 2021, 5:55 a.m. UTC | #2 
On 02/01/2021 08:50 PM, Thomas Bogendoerfer wrote:

> On Wed, Jan 27, 2021 at 12:12:25PM +0800, Jinyang He wrote:
>> Use kimage_vaddr to indicate kernel start address. Provide kaslr_offset()
>> to get the kernel offset when KASLR is enabled. Error may occur before
>> update_kimage_vaddr(), so put it at the end of the offset branch.
>>
>> Fixes: a307a4ce9ecd ("MIPS: Loongson64: Add KASLR support")
>> Reported-by: kernel test robot <lkp@intel.com>
>> Signed-off-by: Jinyang He <hejinyang@loongson.cn>
>> ---
>>   arch/mips/include/asm/page.h |  6 ++++++
>>   arch/mips/kernel/relocate.c  | 12 ++++++++++++
>>   arch/mips/kernel/setup.c     |  3 +++
>>   3 files changed, 21 insertions(+)
>>
>> diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
>> index 6a77bc4..9429520 100644
>> --- a/arch/mips/include/asm/page.h
>> +++ b/arch/mips/include/asm/page.h
>> @@ -255,6 +255,12 @@ extern bool __virt_addr_valid(const volatile void *kaddr);
>>   
>>   #define VM_DATA_DEFAULT_FLAGS	VM_DATA_FLAGS_TSK_EXEC
>>   
>> +extern unsigned long kimage_vaddr;
>> +static inline unsigned long kaslr_offset(void)
>> +{
>> +	return kimage_vaddr - VMLINUX_LOAD_ADDRESS;
>> +}
> this breaks for 32bit kernels:
>
> <command-line>:0:22: error: large integer implicitly truncated to unsigned type [-Werror=overflow]
> /local/tbogendoerfer/korg/linux/arch/mips/kernel/setup.c:87:41: note: in expansion of macro ‘VMLINUX_LOAD_ADDRESS’
>   unsigned long kimage_vaddr __initdata = VMLINUX_LOAD_ADDRESS;
>                                           ^~~~~~~~~~~~~~~~~~~~
> cc1: all warnings being treated as errors
>

Sorry for not considering the 32bits kernel. Maybe a variable is enough.

Like this,

diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index 6a77bc4a6eec..74082e35d57c 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -255,6 +255,12 @@ extern bool __virt_addr_valid(const volatile void 
*kaddr);

  #define VM_DATA_DEFAULT_FLAGS    VM_DATA_FLAGS_TSK_EXEC

+extern unsigned long __kaslr_offset;
+static inline unsigned long kaslr_offset(void)
+{
+    return __kaslr_offset;
+}
+
  #include <asm-generic/memory_model.h>
  #include <asm-generic/getorder.h>

diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
index c643c816cbe0..95abb9c82f00 100644
--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/relocate.c
@@ -300,6 +300,13 @@ static inline int __init relocation_addr_valid(void 
*loc_new)
      return 1;
  }

+static inline void __init update_kaslr_offset(unsigned long *addr, long 
offset)
+{
+    unsigned long *new_addr = (unsigned long *)RELOCATED(addr);
+
+    *new_addr = (unsigned long)offset;
+}
+
  #if defined(CONFIG_USE_OF)
  void __weak *plat_get_fdt(void)
  {
@@ -410,6 +417,9 @@ void *__init relocate_kernel(void)

          /* Return the new kernel's entry point */
          kernel_entry = RELOCATED(start_kernel);
+
+        /* Error may occur before, so keep it at last */
+        update_kaslr_offset(&__kaslr_offset, offset);
      }
  out:
      return kernel_entry;
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 7e1f8e277437..cde234326738 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -84,6 +84,9 @@ static struct resource code_resource = { .name = 
"Kernel code", };
  static struct resource data_resource = { .name = "Kernel data", };
  static struct resource bss_resource = { .name = "Kernel bss", };

+unsigned long __kaslr_offset __initdata = 0;
+EXPORT_SYMBOL(__kaslr_offset);
+
  static void *detect_magic __initdata = detect_memory_region;

  #ifdef CONFIG_MIPS_AUTO_PFN_OFFSET

I'll send v2 later if no other comment.

Thanks,
Jinyang
diff mbox series

Patch

diff --git a/arch/mips/include/asm/page.h b/arch/mips/include/asm/page.h
index 6a77bc4..9429520 100644
--- a/arch/mips/include/asm/page.h
+++ b/arch/mips/include/asm/page.h
@@ -255,6 +255,12 @@  extern bool __virt_addr_valid(const volatile void *kaddr);
 
 #define VM_DATA_DEFAULT_FLAGS	VM_DATA_FLAGS_TSK_EXEC
 
+extern unsigned long kimage_vaddr;
+static inline unsigned long kaslr_offset(void)
+{
+	return kimage_vaddr - VMLINUX_LOAD_ADDRESS;
+}
+
 #include <asm-generic/memory_model.h>
 #include <asm-generic/getorder.h>
 
diff --git a/arch/mips/kernel/relocate.c b/arch/mips/kernel/relocate.c
index c643c81..2cbc3b1 100644
--- a/arch/mips/kernel/relocate.c
+++ b/arch/mips/kernel/relocate.c
@@ -300,6 +300,15 @@  static inline int __init relocation_addr_valid(void *loc_new)
 	return 1;
 }
 
+static inline void __init update_kimage_vaddr(unsigned long value,
+					      unsigned long *addr, long offset)
+{
+	unsigned long new_value = value + offset;
+	unsigned long *new_addr = (void *)addr + offset;
+
+	*new_addr = new_value;
+}
+
 #if defined(CONFIG_USE_OF)
 void __weak *plat_get_fdt(void)
 {
@@ -410,6 +419,9 @@  void *__init relocate_kernel(void)
 
 		/* Return the new kernel's entry point */
 		kernel_entry = RELOCATED(start_kernel);
+
+		/* Error may occur before, so keep it at last */
+		update_kimage_vaddr(kimage_vaddr, &kimage_vaddr, offset);
 	}
 out:
 	return kernel_entry;
diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
index 7e1f8e2..ad37b24 100644
--- a/arch/mips/kernel/setup.c
+++ b/arch/mips/kernel/setup.c
@@ -84,6 +84,9 @@  static struct resource code_resource = { .name = "Kernel code", };
 static struct resource data_resource = { .name = "Kernel data", };
 static struct resource bss_resource = { .name = "Kernel bss", };
 
+unsigned long kimage_vaddr __initdata = VMLINUX_LOAD_ADDRESS;
+EXPORT_SYMBOL(kimage_vaddr);
+
 static void *detect_magic __initdata = detect_memory_region;
 
 #ifdef CONFIG_MIPS_AUTO_PFN_OFFSET