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Subject[PATCH RFC 4/8] powerpc/64s: Add support for ori barrier_nospec
Date
Copypasta from rfi implementation

Signed-off-by: Michal Suchanek <msuchanek@suse.de>
---
arch/powerpc/include/asm/barrier.h | 4 ++--
arch/powerpc/include/asm/feature-fixups.h | 9 +++++++++
arch/powerpc/include/asm/setup.h | 8 ++++++++
arch/powerpc/kernel/setup_64.c | 29 +++++++++++++++++++++++++++++
arch/powerpc/kernel/vmlinux.lds.S | 7 +++++++
arch/powerpc/lib/feature-fixups.c | 27 +++++++++++++++++++++++++++
6 files changed, 82 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/barrier.h b/arch/powerpc/include/asm/barrier.h
index 8e47b3abe405..4079a95e84c2 100644
--- a/arch/powerpc/include/asm/barrier.h
+++ b/arch/powerpc/include/asm/barrier.h
@@ -75,9 +75,9 @@ do { \
___p1; \
})

-/* TODO: add patching so this can be disabled */
/* Prevent speculative execution past this barrier. */
-#define barrier_nospec_asm ori 31,31,0
+#define barrier_nospec_asm SPEC_BARRIER_FIXUP_SECTION; \
+ nop
#ifdef __ASSEMBLY__
#define barrier_nospec barrier_nospec_asm
#else
diff --git a/arch/powerpc/include/asm/feature-fixups.h b/arch/powerpc/include/asm/feature-fixups.h
index 1e82eb3caabd..9d3382618ffd 100644
--- a/arch/powerpc/include/asm/feature-fixups.h
+++ b/arch/powerpc/include/asm/feature-fixups.h
@@ -195,11 +195,20 @@ label##3: \
FTR_ENTRY_OFFSET 951b-952b; \
.popsection;

+#define SPEC_BARRIER_FIXUP_SECTION \
+953: \
+ .pushsection __spec_barrier_fixup,"a"; \
+ .align 2; \
+954: \
+ FTR_ENTRY_OFFSET 953b-954b; \
+ .popsection;
+

#ifndef __ASSEMBLY__
#include <linux/types.h>

extern long __start___rfi_flush_fixup, __stop___rfi_flush_fixup;
+extern long __start___spec_barrier_fixup, __stop___spec_barrier_fixup;

void apply_feature_fixups(void);
void setup_feature_keys(void);
diff --git a/arch/powerpc/include/asm/setup.h b/arch/powerpc/include/asm/setup.h
index 469b7fdc9be4..486d02e4a310 100644
--- a/arch/powerpc/include/asm/setup.h
+++ b/arch/powerpc/include/asm/setup.h
@@ -49,8 +49,16 @@ enum l1d_flush_type {
L1D_FLUSH_MTTRIG = 0x8,
};

+/* These are bit flags */
+enum spec_barrier_type {
+ SPEC_BARRIER_NONE = 0x1,
+ SPEC_BARRIER_ORI = 0x2,
+};
+
void __init setup_rfi_flush(enum l1d_flush_type, bool enable);
void do_rfi_flush_fixups(enum l1d_flush_type types);
+void __init setup_barrier_nospec(enum spec_barrier_type, bool enable);
+void do_barrier_nospec_fixups(enum spec_barrier_type type);

#endif /* !__ASSEMBLY__ */

diff --git a/arch/powerpc/kernel/setup_64.c b/arch/powerpc/kernel/setup_64.c
index c388cc3357fa..09f21a954bfc 100644
--- a/arch/powerpc/kernel/setup_64.c
+++ b/arch/powerpc/kernel/setup_64.c
@@ -815,6 +815,10 @@ static enum l1d_flush_type enabled_flush_types;
static void *l1d_flush_fallback_area;
static bool no_rfi_flush;
bool rfi_flush;
+enum spec_barrier_type powerpc_barrier_nospec;
+static enum spec_barrier_type barrier_nospec_type;
+static bool no_nospec;
+bool barrier_nospec_enabled;

static int __init handle_no_rfi_flush(char *p)
{
@@ -899,6 +903,31 @@ void __init setup_rfi_flush(enum l1d_flush_type types, bool enable)
rfi_flush_enable(enable);
}

+void barrier_nospec_enable(bool enable)
+{
+ barrier_nospec_enabled = enable;
+
+ if (enable) {
+ powerpc_barrier_nospec = barrier_nospec_type;
+ do_barrier_nospec_fixups(powerpc_barrier_nospec);
+ on_each_cpu(do_nothing, NULL, 1);
+ } else {
+ powerpc_barrier_nospec = SPEC_BARRIER_NONE;
+ do_barrier_nospec_fixups(powerpc_barrier_nospec);
+ }
+}
+
+void __init setup_barrier_nospec(enum spec_barrier_type type, bool enable)
+{
+ if (type & SPEC_BARRIER_ORI)
+ pr_info("barrier_nospec: Using ori type flush\n");
+
+ barrier_nospec_type = type;
+
+ if (!no_nospec)
+ barrier_nospec_enable(enable);
+}
+
#ifdef CONFIG_DEBUG_FS
static int rfi_flush_set(void *data, u64 val)
{
diff --git a/arch/powerpc/kernel/vmlinux.lds.S b/arch/powerpc/kernel/vmlinux.lds.S
index c8af90ff49f0..744b58ff77f1 100644
--- a/arch/powerpc/kernel/vmlinux.lds.S
+++ b/arch/powerpc/kernel/vmlinux.lds.S
@@ -139,6 +139,13 @@ SECTIONS
*(__rfi_flush_fixup)
__stop___rfi_flush_fixup = .;
}
+
+ . = ALIGN(8);
+ __spec_barrier_fixup : AT(ADDR(__spec_barrier_fixup) - LOAD_OFFSET) {
+ __start___spec_barrier_fixup = .;
+ *(__spec_barrier_fixup)
+ __stop___spec_barrier_fixup = .;
+ }
#endif

EXCEPTION_TABLE(0)
diff --git a/arch/powerpc/lib/feature-fixups.c b/arch/powerpc/lib/feature-fixups.c
index 73697c4e3468..000e153184ad 100644
--- a/arch/powerpc/lib/feature-fixups.c
+++ b/arch/powerpc/lib/feature-fixups.c
@@ -155,6 +155,33 @@ void do_rfi_flush_fixups(enum l1d_flush_type types)

printk(KERN_DEBUG "rfi-flush: patched %d locations\n", i);
}
+
+void do_barrier_nospec_fixups(enum spec_barrier_type type)
+{
+ unsigned int instr, *dest;
+ long *start, *end;
+ int i;
+
+ start = PTRRELOC(&__start___spec_barrier_fixup),
+ end = PTRRELOC(&__stop___spec_barrier_fixup);
+
+ instr = 0x60000000; /* nop */
+
+ if (type == SPEC_BARRIER_ORI) {
+ pr_info("barrier_nospec: using ORI speculation barrier\n");
+ instr = 0x63ff0000; /* ori 31,31,0 speculation barrier */
+ }
+
+ for (i = 0; start < end; start++, i++) {
+ dest = (void *)start + *start;
+
+ pr_devel("patching dest %lx\n", (unsigned long)dest);
+ patch_instruction(dest, instr);
+ }
+
+ printk(KERN_DEBUG "barrier-nospec: patched %d locations\n", i);
+}
+
#endif /* CONFIG_PPC_BOOK3S_64 */

void do_lwsync_fixups(unsigned long value, void *fixup_start, void *fixup_end)
--
2.13.6
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