linux-kernel - [PATCH RFC rebase 4/9] powerpc/64s: Use barrier_nospec in RFI_FLUSH

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Date:   Thu, 15 Mar 2018 20:15:53 +0100
From:   Michal Suchanek <msuchanek@...e.de>
To:     linuxppc-dev@...ts.ozlabs.org
Cc:     Kate Stewart <kstewart@...uxfoundation.org>,
        Madhavan Srinivasan <maddy@...ux.vnet.ibm.com>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Neuling <mikey@...ling.org>,
        "Bryant G. Ly" <bryantly@...ux.vnet.ibm.com>,
        Mahesh Salgaonkar <mahesh@...ux.vnet.ibm.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.vnet.ibm.com>,
        Daniel Axtens <dja@...ens.net>,
        Nicholas Piggin <npiggin@...il.com>,
        Al Viro <viro@...iv.linux.org.uk>,
        David Gibson <david@...son.dropbear.id.au>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Cédric Le Goater <clg@...d.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Donnellan <andrew.donnellan@....ibm.com>,
        Philippe Ombredanne <pombredanne@...b.com>,
        Joe Perches <joe@...ches.com>,
        Oliver O'Halloran <oohall@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Tobin C. Harding" <me@...in.cc>,
        Michal Suchanek <msuchanek@...e.de>
Subject: [PATCH RFC rebase 4/9] powerpc/64s: Use barrier_nospec in RFI_FLUSH_SLOT

The RFI flush support patches the speculation barrier into
RFI_FLUSH_SLOT as part of the RFI flush. Use separate barrier_nospec
instead.

Signed-off-by: Michal Suchanek <msuchanek@...e.de>
---
 arch/powerpc/include/asm/exception-64s.h | 2 +-
 arch/powerpc/lib/feature-fixups.c        | 9 +++------
 2 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/include/asm/exception-64s.h b/arch/powerpc/include/asm/exception-64s.h
index 471b2274fbeb..bb5a3052b29b 100644
--- a/arch/powerpc/include/asm/exception-64s.h
+++ b/arch/powerpc/include/asm/exception-64s.h
@@ -81,9 +81,9 @@
  * L1-D cache when returning to userspace or a guest.
  */
 #define RFI_FLUSH_SLOT							\
+	barrier_nospec_asm;						\
 	RFI_FLUSH_FIXUP_SECTION;					\
 	nop;								\
-	nop;								\
 	nop
 
 #define RFI_TO_KERNEL							\
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 35f80ab7cbd8..4cc2f0c5c863 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -119,7 +119,7 @@ void do_feature_fixups(unsigned long value, void *fixup_start, void *fixup_end)
 #ifdef CONFIG_PPC_BOOK3S_64
 void do_rfi_flush_fixups(enum l1d_flush_type types)
 {
-	unsigned int instrs[3], *dest;
+	unsigned int instrs[2], *dest;
 	long *start, *end;
 	int i;
 
@@ -128,15 +128,13 @@ void do_rfi_flush_fixups(enum l1d_flush_type types)
 
 	instrs[0] = 0x60000000; /* nop */
 	instrs[1] = 0x60000000; /* nop */
-	instrs[2] = 0x60000000; /* nop */
 
 	if (types & L1D_FLUSH_FALLBACK)
-		/* b .+16 to fallback flush */
-		instrs[0] = 0x48000010;
+		/* b .+12 to fallback flush */
+		instrs[0] = 0x4800000c;
 
 	i = 0;
 	if (types & L1D_FLUSH_ORI) {
-		instrs[i++] = 0x63ff0000; /* ori 31,31,0 speculation barrier */
 		instrs[i++] = 0x63de0000; /* ori 30,30,0 L1d flush*/
 	}
 
@@ -150,7 +148,6 @@ void do_rfi_flush_fixups(enum l1d_flush_type types)
 
 		patch_instruction(dest, instrs[0]);
 		patch_instruction(dest + 1, instrs[1]);
-		patch_instruction(dest + 2, instrs[2]);
 	}
 
 	printk(KERN_DEBUG "rfi-flush: patched %d locations (%s flush)\n", i,
-- 
2.13.6