[PATCH stable v4.4 27/52] powerpc/64s: Patch barrier_nospec in modules

[Michael Ellerman]

From: Michal Suchanek <msuchanek at suse.de>

commit 815069ca57c142eb71d27439bc27f41a433a67b3 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 at suse.de>
Signed-off-by: Michael Ellerman <mpe at ellerman.id.au>
---
 arch/powerpc/include/asm/setup.h  |  7 +++++++
 arch/powerpc/kernel/module.c      |  6 ++++++
 arch/powerpc/kernel/security.c    |  2 +-
 arch/powerpc/lib/feature-fixups.c | 16 +++++++++++++---
 4 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 80c35275bbdb..fed0b352e24f 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -39,6 +39,13 @@ 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__ */
 
diff --git a/arch/powerpc/kernel/module.c b/arch/powerpc/kernel/module.c
index 9547381b631a..340528d79233 100644
--- a/arch/powerpc/kernel/module.c
+++ b/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");
diff --git a/arch/powerpc/kernel/security.c b/arch/powerpc/kernel/security.c
index 0b7f6471f8f5..a1ae02f9d03d 100644
--- a/arch/powerpc/kernel/security.c
+++ b/arch/powerpc/kernel/security.c
@@ -16,7 +16,7 @@
 
 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)
 {
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 17a3c2d5c80b..e9373f41f0da 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/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)
-- 
2.20.1