x86/kexec: Move relocate_kernel to kernel .data section

Now that the copy is executed instead of the original, the relocate_kernel
page can live in the kernel's .text section. This will allow subsequent
commits to actually add real data to it and clean up the code somewhat as
well as making the control page ROX.

Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>

diff --git a/arch/x86/include/asm/sections.h b/arch/x86/include/asm/sections.h
index 3fa87e5e11aba92e17737164894de5a299431d6d..30e8ee7006f9a7a43d07a4647b0e8cc087496b5f 100644 (file)
--- a/arch/x86/include/asm/sections.h
+++ b/arch/x86/include/asm/sections.h
@@ -5,6 +5,7 @@
 #include <asm-generic/sections.h>
 #include <asm/extable.h>
 
+extern char __relocate_kernel_start[], __relocate_kernel_end[];
 extern char __brk_base[], __brk_limit[];
 extern char __end_rodata_aligned[];
 

diff --git a/arch/x86/kernel/callthunks.c b/arch/x86/kernel/callthunks.c
index 4656474567533bc9398e814ac8fd78df172cfdd1..51c3e0049152df87f8623d4b5e7c65687e3d5a1c 100644 (file)
--- a/arch/x86/kernel/callthunks.c
+++ b/arch/x86/kernel/callthunks.c
@@ -139,9 +139,15 @@ static bool skip_addr(void *dest)
                return true;
 #endif
 #ifdef CONFIG_KEXEC_CORE
+# ifdef CONFIG_X86_64
+       if (dest >= (void *)__relocate_kernel_start &&
+           dest < (void *)__relocate_kernel_end)
+               return true;
+# else
        if (dest >= (void *)relocate_kernel &&
            dest < (void*)relocate_kernel + KEXEC_CONTROL_CODE_MAX_SIZE)
                return true;
+# endif
 #endif
 #ifdef CONFIG_XEN
        if (dest >= (void *)hypercall_page &&

diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
index 9567347f7a9b483d2bf610a74bf0c1a069b05d2d..23dffdc070ddf5f8bc84287e19a69afe2342498a 100644 (file)
--- a/arch/x86/kernel/machine_kexec_64.c
+++ b/arch/x86/kernel/machine_kexec_64.c
@@ -307,6 +307,8 @@ static void load_segments(void)
 int machine_kexec_prepare(struct kimage *image)
 {
        void *control_page = page_address(image->control_code_page);
+       unsigned long reloc_start = (unsigned long)__relocate_kernel_start;
+       unsigned long reloc_end = (unsigned long)__relocate_kernel_end;
        int result;
 
        /* Setup the identity mapped 64bit page table */
@@ -314,7 +316,7 @@ int machine_kexec_prepare(struct kimage *image)
        if (result)
                return result;
 
-       __memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
+       __memcpy(control_page, __relocate_kernel_start, reloc_end - reloc_start);
 
        set_memory_x((unsigned long)control_page, 1);
 

diff --git a/arch/x86/kernel/relocate_kernel_64.S b/arch/x86/kernel/relocate_kernel_64.S
index b48bd82843fdee258fb9b16f84e5875fc941ebce..01138f862c599f178f54d9d57938a07299c1dc14 100644 (file)
--- a/arch/x86/kernel/relocate_kernel_64.S
+++ b/arch/x86/kernel/relocate_kernel_64.S
@@ -41,10 +41,8 @@
 #define CP_PA_BACKUP_PAGES_MAP DATA(0x30)
 #define CP_VA_CONTROL_PAGE     DATA(0x38)
 
-       .text
-       .align PAGE_SIZE
+       .section .text.relocate_kernel,"ax";
        .code64
-SYM_CODE_START_NOALIGN(relocate_range)
 SYM_CODE_START_NOALIGN(relocate_kernel)
        UNWIND_HINT_END_OF_STACK
        ANNOTATE_NOENDBR
@@ -341,6 +339,3 @@ SYM_CODE_START_LOCAL_NOALIGN(swap_pages)
        ret
        int3
 SYM_CODE_END(swap_pages)
-
-       .skip KEXEC_CONTROL_CODE_MAX_SIZE - (. - relocate_kernel), 0xcc
-SYM_CODE_END(relocate_range);

diff --git a/arch/x86/kernel/vmlinux.lds.S b/arch/x86/kernel/vmlinux.lds.S
index fab3ac9a4574ab406fee90e6c5d86fd4a81af319..17ebaa441e87594af57d817a89cfcbeaae015446 100644 (file)
--- a/arch/x86/kernel/vmlinux.lds.S
+++ b/arch/x86/kernel/vmlinux.lds.S
@@ -28,6 +28,7 @@
 #include <asm/orc_lookup.h>
 #include <asm/cache.h>
 #include <asm/boot.h>
+#include <asm/kexec.h>
 
 #undef i386     /* in case the preprocessor is a 32bit one */
 
@@ -95,7 +96,18 @@ const_pcpu_hot = pcpu_hot;
 #define BSS_DECRYPTED
 
 #endif
-
+#if defined(CONFIG_X86_64) && defined(CONFIG_KEXEC_CORE)
+#define KEXEC_RELOCATE_KERNEL                                  \
+       . = ALIGN(0x100);                                       \
+       __relocate_kernel_start = .;                            \
+       *(.text.relocate_kernel);                               \
+       __relocate_kernel_end = .;
+
+ASSERT(__relocate_kernel_end - __relocate_kernel_start <= KEXEC_CONTROL_CODE_MAX_SIZE,
+       "relocate_kernel code too large!")
+#else
+#define KEXEC_RELOCATE_KERNEL
+#endif
 PHDRS {
        text PT_LOAD FLAGS(5);          /* R_E */
        data PT_LOAD FLAGS(6);          /* RW_ */
@@ -181,6 +193,7 @@ SECTIONS
 
                DATA_DATA
                CONSTRUCTORS
+               KEXEC_RELOCATE_KERNEL
 
                /* rarely changed data like cpu maps */
                READ_MOSTLY_DATA(INTERNODE_CACHE_BYTES)