powerpc/64: Add CONFIG_PPC_BARRIER_NOSPEC

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

commit 179ab1cb upstream.

Add a config symbol to encode which platforms support the
barrier_nospec speculation barrier. Currently this is just Book3S 64
but we will add Book3E in a future patch.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[juergh:
 - Adjusted context.
 - Updated Ubuntu config.]
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/Kconfig

@@ -136,7 +136,7 @@ config PPC
 	select GENERIC_SMP_IDLE_THREAD
 	select GENERIC_CMOS_UPDATE
 	select GENERIC_TIME_VSYSCALL_OLD
-	select GENERIC_CPU_VULNERABILITIES	if PPC_BOOK3S_64
+	select GENERIC_CPU_VULNERABILITIES	if PPC_BARRIER_NOSPEC
 	select GENERIC_CLOCKEVENTS
 	select GENERIC_CLOCKEVENTS_BROADCAST if SMP
 	select ARCH_HAS_TICK_BROADCAST if GENERIC_CLOCKEVENTS_BROADCAST
@@ -163,6 +163,11 @@ config PPC
 	select HAVE_ARCH_SECCOMP_FILTER
 	select GENERIC_CPU_AUTOPROBE
 
+config PPC_BARRIER_NOSPEC
+	bool
+	default y
+	depends on PPC_BOOK3S_64
+
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN
 

arch/powerpc/include/asm/barrier.h

@@ -92,7 +92,7 @@ do {									\
 #define smp_mb__after_atomic()      smp_mb()
 #define smp_mb__before_spinlock()   smp_mb()
 
-#ifdef CONFIG_PPC_BOOK3S_64
+#ifdef CONFIG_PPC_BARRIER_NOSPEC
 /*
  * Prevent execution of subsequent instructions until preceding branches have
  * been fully resolved and are no longer executing speculatively.
@@ -102,9 +102,9 @@ do {									\
 // This also acts as a compiler barrier due to the memory clobber.
 #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")
 
-#else /* !CONFIG_PPC_BOOK3S_64 */
+#else /* !CONFIG_PPC_BARRIER_NOSPEC */
 #define barrier_nospec_asm
 #define barrier_nospec()
-#endif
+#endif /* CONFIG_PPC_BARRIER_NOSPEC */
 
 #endif /* _ASM_POWERPC_BARRIER_H */

arch/powerpc/include/asm/setup.h

@@ -41,7 +41,7 @@ void setup_barrier_nospec(void);
 void do_barrier_nospec_fixups(bool enable);
 extern bool barrier_nospec_enabled;
 
-#ifdef CONFIG_PPC_BOOK3S_64
+#ifdef CONFIG_PPC_BARRIER_NOSPEC
 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) { };

arch/powerpc/kernel/Makefile

@@ -40,10 +40,11 @@ obj-$(CONFIG_PPC64)		+= setup_64.o sys_ppc32.o \
 obj-$(CONFIG_VDSO32)		+= vdso32/
 obj-$(CONFIG_HAVE_HW_BREAKPOINT)	+= hw_breakpoint.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_ppc970.o cpu_setup_pa6t.o
-obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_power.o security.o
+obj-$(CONFIG_PPC_BOOK3S_64)	+= cpu_setup_power.o
 obj-$(CONFIG_PPC_BOOK3S_64)	+= mce.o mce_power.o hmi.o
 obj64-$(CONFIG_RELOCATABLE)	+= reloc_64.o
 obj-$(CONFIG_PPC_BOOK3E_64)	+= exceptions-64e.o idle_book3e.o
+obj-$(CONFIG_PPC_BARRIER_NOSPEC) += security.o
 obj-$(CONFIG_PPC64)		+= vdso64/
 obj-$(CONFIG_ALTIVEC)		+= vecemu.o
 obj-$(CONFIG_PPC_970_NAP)	+= idle_power4.o

arch/powerpc/kernel/module.c

@@ -67,13 +67,15 @@ int module_finalize(const Elf_Ehdr *hdr,
 		do_feature_fixups(powerpc_firmware_features,
 				  (void *)sect->sh_addr,
 				  (void *)sect->sh_addr + sect->sh_size);
+#endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_PPC_BARRIER_NOSPEC
 	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
+#endif /* CONFIG_PPC_BARRIER_NOSPEC */
 
 	sect = find_section(hdr, sechdrs, "__lwsync_fixup");
 	if (sect != NULL)

arch/powerpc/kernel/vmlinux.lds.S

@@ -93,14 +93,16 @@ SECTIONS
 		*(__rfi_flush_fixup)
 		__stop___rfi_flush_fixup = .;
 	}
+#endif /* CONFIG_PPC64 */
 
+#ifdef CONFIG_PPC_BARRIER_NOSPEC
 	. = ALIGN(8);
 	__spec_barrier_fixup : AT(ADDR(__spec_barrier_fixup) - LOAD_OFFSET) {
 		__start___barrier_nospec_fixup = .;
 		*(__barrier_nospec_fixup)
 		__stop___barrier_nospec_fixup = .;
 	}
-#endif
+#endif /* CONFIG_PPC_BARRIER_NOSPEC */
 
 	EXCEPTION_TABLE(0)
 

arch/powerpc/lib/feature-fixups.c

@@ -301,6 +301,9 @@ void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_
 	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
 }
 
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
+#ifdef CONFIG_PPC_BARRIER_NOSPEC
 void do_barrier_nospec_fixups(bool enable)
 {
 	void *start, *end;
@@ -310,8 +313,7 @@ void do_barrier_nospec_fixups(bool enable)
 
 	do_barrier_nospec_fixups_range(enable, start, end);
 }
-
-#endif /* CONFIG_PPC_BOOK3S_64 */
+#endif /* CONFIG_PPC_BARRIER_NOSPEC */
 
 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 {

debian.master/config/config.common.ubuntu

@@ -5954,6 +5954,7 @@ CONFIG_PPC_ADV_DEBUG_DACS=2
 CONFIG_PPC_ADV_DEBUG_DVCS=0
 CONFIG_PPC_ADV_DEBUG_IACS=2
 CONFIG_PPC_ADV_DEBUG_REGS=y
+CONFIG_PPC_BARRIER_NOSPEC=y
 CONFIG_PPC_BOOK3E=y
 CONFIG_PPC_BOOK3E_MMU=y
 CONFIG_PPC_BOOK3S=y