powerpc/fsl: Add barrier_nospec implementation for NXP PowerPC Book3E

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

commit ebcd1bfc upstream.

Implement the barrier_nospec as a isync;sync instruction sequence.
The implementation uses the infrastructure built for BOOK3S 64.
Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
[mpe: Add PPC_INST_ISYNC for backport]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[juergh: Adjusted context.]
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/powerpc/Kconfig

@@ -166,7 +166,7 @@ config PPC
 config PPC_BARRIER_NOSPEC
 	bool
 	default y
-	depends on PPC_BOOK3S_64
+	depends on PPC_BOOK3S_64 || PPC_FSL_BOOK3E
 
 config GENERIC_CSUM
 	def_bool CPU_LITTLE_ENDIAN

arch/powerpc/include/asm/barrier.h

@@ -92,12 +92,18 @@ do {									\
 #define smp_mb__after_atomic()      smp_mb()
 #define smp_mb__before_spinlock()   smp_mb()
 
+#ifdef CONFIG_PPC_BOOK3S_64
+#define NOSPEC_BARRIER_SLOT   nop
+#elif defined(CONFIG_PPC_FSL_BOOK3E)
+#define NOSPEC_BARRIER_SLOT   nop; nop
+#endif
+
 #ifdef CONFIG_PPC_BARRIER_NOSPEC
 /*
  * Prevent execution of subsequent instructions until preceding branches have
  * been fully resolved and are no longer executing speculatively.
  */
-#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; nop
+#define barrier_nospec_asm NOSPEC_BARRIER_FIXUP_SECTION; NOSPEC_BARRIER_SLOT
 
 // This also acts as a compiler barrier due to the memory clobber.
 #define barrier_nospec() asm (stringify_in_c(barrier_nospec_asm) ::: "memory")

arch/powerpc/include/asm/ppc-opcode.h

@@ -147,6 +147,7 @@
 #define PPC_INST_LWSYNC			0x7c2004ac
 #define PPC_INST_SYNC			0x7c0004ac
 #define PPC_INST_SYNC_MASK		0xfc0007fe
+#define PPC_INST_ISYNC			0x4c00012c
 #define PPC_INST_LXVD2X			0x7c000698
 #define PPC_INST_MCRXR			0x7c000400
 #define PPC_INST_MCRXR_MASK		0xfc0007fe

arch/powerpc/lib/feature-fixups.c

@@ -315,6 +315,37 @@ void do_barrier_nospec_fixups(bool enable)
 }
 #endif /* CONFIG_PPC_BARRIER_NOSPEC */
 
+#ifdef CONFIG_PPC_FSL_BOOK3E
+void do_barrier_nospec_fixups_range(bool enable, void *fixup_start, void *fixup_end)
+{
+	unsigned int instr[2], *dest;
+	long *start, *end;
+	int i;
+
+	start = fixup_start;
+	end = fixup_end;
+
+	instr[0] = PPC_INST_NOP;
+	instr[1] = PPC_INST_NOP;
+
+	if (enable) {
+		pr_info("barrier-nospec: using isync; sync as speculation barrier\n");
+		instr[0] = PPC_INST_ISYNC;
+		instr[1] = PPC_INST_SYNC;
+	}
+
+	for (i = 0; start < end; start++, i++) {
+		dest = (void *)start + *start;
+
+		pr_devel("patching dest %lx\n", (unsigned long)dest);
+		patch_instruction(dest, instr[0]);
+		patch_instruction(dest + 1, instr[1]);
+	}
+
+	printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
+}
+#endif /* CONFIG_PPC_FSL_BOOK3E */
+
 void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 {
 	long *start, *end;