powerpc/kprobes: Mark newly allocated probes as ROX

Add the arch specific insn page allocator for powerpc. This allocates
ROX pages if STRICT_KERNEL_RWX is enabled. These pages are only written
to with patch_instruction() which is able to write RO pages.

Signed-off-by: Russell Currey <ruscur@russell.cc>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[jpn: Reword commit message, switch to __vmalloc_node_range()]
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Reviewed-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210609013431.9805-5-jniethe5@gmail.com

diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index b19dfc4..8ac248c 100644 (file)
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -19,11 +19,13 @@
 #include <linux/extable.h>
 #include <linux/kdebug.h>
 #include <linux/slab.h>
+#include <linux/moduleloader.h>
 #include <asm/code-patching.h>
 #include <asm/cacheflush.h>
 #include <asm/sstep.h>
 #include <asm/sections.h>
 #include <asm/inst.h>
+#include <asm/set_memory.h>
 #include <linux/uaccess.h>
 
 DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@@ -103,6 +105,21 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset)
        return addr;
 }
 
+void *alloc_insn_page(void)
+{
+       void *page;
+
+       page = module_alloc(PAGE_SIZE);
+       if (!page)
+               return NULL;
+
+       if (strict_module_rwx_enabled()) {
+               set_memory_ro((unsigned long)page, 1);
+               set_memory_x((unsigned long)page, 1);
+       }
+       return page;
+}
+
 int arch_prepare_kprobe(struct kprobe *p)
 {
        int ret = 0;