Re: [PATCH] MIPS: relocatable: Provide kaslr_offset() to get the kernel offset

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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@xxxxxxxxx>
Signed-off-by: Jinyang He <hejinyang@xxxxxxxxxxx>
---
  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





[Index of Archives]     [LKML Archive]     [Linux ARM Kernel]     [Linux ARM]     [Git]     [Yosemite News]     [Linux SCSI]     [Linux Hams]

  Powered by Linux