powerpc/64s: Patch barrier_nospec in modules

BugLink: https://bugs.launchpad.net/bugs/1830176

commit 815069ca upstream.

Note that unlike RFI which is patched only in kernel the nospec state
reflects settings at the time the module was loaded.

Iterating all modules and re-patching every time the settings change
is not implemented.

Based on lwsync patching.
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/include/asm/setup.h

@@ -38,6 +38,13 @@ enum l1d_flush_type {
 void setup_rfi_flush(enum l1d_flush_type, bool enable);
 void do_rfi_flush_fixups(enum l1d_flush_type types);
 void do_barrier_nospec_fixups(bool enable);
+extern bool barrier_nospec_enabled;
+
+#ifdef CONFIG_PPC_BOOK3S_64
+void do_barrier_nospec_fixups_range(bool enable, void *start, void *end);
+#else
+static inline void do_barrier_nospec_fixups_range(bool enable, void *start, void *end) { };
+#endif
 
 #endif /* !__ASSEMBLY__ */
 

arch/powerpc/kernel/module.c

@@ -67,6 +67,12 @@ int module_finalize(const Elf_Ehdr *hdr,
 		do_feature_fixups(powerpc_firmware_features,
 				  (void *)sect->sh_addr,
 				  (void *)sect->sh_addr + sect->sh_size);
+
+	sect = find_section(hdr, sechdrs, "__spec_barrier_fixup");
+	if (sect != NULL)
+		do_barrier_nospec_fixups_range(barrier_nospec_enabled,
+				  (void *)sect->sh_addr,
+				  (void *)sect->sh_addr + sect->sh_size);
 #endif
 
 	sect = find_section(hdr, sechdrs, "__lwsync_fixup");

arch/powerpc/kernel/security.c

@@ -17,7 +17,7 @@
 
 unsigned long powerpc_security_features __read_mostly = SEC_FTR_DEFAULT;
 
-static bool barrier_nospec_enabled;
+bool barrier_nospec_enabled;
 
 static void enable_barrier_nospec(bool enable)
 {

arch/powerpc/lib/feature-fixups.c

@@ -275,14 +275,14 @@ void do_rfi_flush_fixups(enum l1d_flush_type types)
 						: "unknown");
 }
 
-void do_barrier_nospec_fixups(bool enable)
+void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_end)
 {
 	unsigned int instr, *dest;
 	long *start, *end;
 	int i;
 
-	start = PTRRELOC(&__start___barrier_nospec_fixup),
-	end = PTRRELOC(&__stop___barrier_nospec_fixup);
+	start = fixup_start;
+	end = fixup_end;
 
 	instr = 0x60000000; /* nop */
 
@@ -301,6 +301,16 @@ void do_barrier_nospec_fixups(bool enable)
 	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
 }
 
+void do_barrier_nospec_fixups(bool enable)
+{
+	void *start, *end;
+
+	start = PTRRELOC(&__start___barrier_nospec_fixup),
+	end = PTRRELOC(&__stop___barrier_nospec_fixup);
+
+	do_barrier_nospec_fixups_range(enable, start, end);
+}
+
 #endif /* CONFIG_PPC_BOOK3S_64 */
 
 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)