powerpc/modules: Make module_alloc() Strict Module RWX aware

Make module_alloc() use PAGE_KERNEL protections instead of
PAGE_KERNEL_EXEX if Strict Module RWX is enabled.
Signed-off-by: Jordan Niethe <jniethe5@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210609013431.9805-4-jniethe5@gmail.com

arch/powerpc/include/asm/mmu.h

@@ -345,6 +345,11 @@ static inline bool strict_kernel_rwx_enabled(void)
 	return false;
 }
 #endif
+
+static inline bool strict_module_rwx_enabled(void)
+{
+	return IS_ENABLED(CONFIG_STRICT_MODULE_RWX) && strict_kernel_rwx_enabled();
+}
 #endif /* !__ASSEMBLY__ */
 
 /* The kernel use the constants below to index in the page sizes array.

arch/powerpc/kernel/module.c

@@ -92,12 +92,14 @@ int module_finalize(const Elf_Ehdr *hdr,
 static __always_inline void *
 __module_alloc(unsigned long size, unsigned long start, unsigned long end)
 {
+	pgprot_t prot = strict_module_rwx_enabled() ? PAGE_KERNEL : PAGE_KERNEL_EXEC;
+
 	/*
 	 * Don't do huge page allocations for modules yet until more testing
 	 * is done. STRICT_MODULE_RWX may require extra work to support this
 	 * too.
 	 */
-	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,
+	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, prot,
 				    VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,
 				    NUMA_NO_NODE, __builtin_return_address(0));
 }