]> git.karo-electronics.de Git - linux-beck.git/commitdiff
KVM guest: Make pv trampoline code executable
authorAlexander Graf <agraf@suse.de>
Tue, 29 Apr 2014 10:17:26 +0000 (12:17 +0200)
committerAlexander Graf <agraf@suse.de>
Tue, 29 Apr 2014 10:36:09 +0000 (12:36 +0200)
Our PV guest patching code assembles chunks of instructions on the fly when it
encounters more complicated instructions to hijack. These instructions need
to live in a section that we don't mark as non-executable, as otherwise we
fault when jumping there.

Right now we put it into the .bss section where it automatically gets marked
as non-executable. Add a check to the NX setting function to ensure that we
leave these particular pages executable.

Signed-off-by: Alexander Graf <agraf@suse.de>
arch/powerpc/include/asm/sections.h
arch/powerpc/kernel/kvm.c
arch/powerpc/mm/hash_utils_64.c

index d0e784e0ff484f0053f807e081a4c89fec13dee6..52179033067262f8f107be29c16b1fba6b8d4cee 100644 (file)
@@ -39,6 +39,17 @@ static inline int overlaps_kernel_text(unsigned long start, unsigned long end)
                (unsigned long)_stext < end;
 }
 
+static inline int overlaps_kvm_tmp(unsigned long start, unsigned long end)
+{
+#ifdef CONFIG_KVM_GUEST
+       extern char kvm_tmp[];
+       return start < (unsigned long)kvm_tmp &&
+               (unsigned long)&kvm_tmp[1024 * 1024] < end;
+#else
+       return 0;
+#endif
+}
+
 #undef dereference_function_descriptor
 static inline void *dereference_function_descriptor(void *ptr)
 {
index 6a0175297b0d8e92495ce97e7274ecba72fcb790..dd8695f6cb6d2c6de9bca80b073f4f40013cdeef 100644 (file)
@@ -74,7 +74,7 @@
 #define KVM_INST_MTSRIN                0x7c0001e4
 
 static bool kvm_patching_worked = true;
-static char kvm_tmp[1024 * 1024];
+char kvm_tmp[1024 * 1024];
 static int kvm_tmp_index;
 
 static inline void kvm_patch_ins(u32 *inst, u32 new_inst)
index d766d6ee33fe6889e5a96b3898f8c47b0050fc14..06ba83b036d3360bb8750b1a869dfcf9e09705d0 100644 (file)
@@ -207,6 +207,10 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
                if (overlaps_kernel_text(vaddr, vaddr + step))
                        tprot &= ~HPTE_R_N;
 
+               /* Make kvm guest trampolines executable */
+               if (overlaps_kvm_tmp(vaddr, vaddr + step))
+                       tprot &= ~HPTE_R_N;
+
                /*
                 * If relocatable, check if it overlaps interrupt vectors that
                 * are copied down to real 0. For relocatable kernel