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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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