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    Subject[PATCH 4.14 054/167] x86/speculation: Clean up various Spectre related details
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Ingo Molnar <mingo@kernel.org>

    commit 21e433bdb95bdf3aa48226fd3d33af608437f293 upstream.

    Harmonize all the Spectre messages so that a:

    dmesg | grep -i spectre

    ... gives us most Spectre related kernel boot messages.

    Also fix a few other details:

    - clarify a comment about firmware speculation control

    - s/KPTI/PTI

    - remove various line-breaks that made the code uglier

    Acked-by: David Woodhouse <dwmw@amazon.co.uk>
    Cc: Andy Lutomirski <luto@kernel.org>
    Cc: Arjan van de Ven <arjan@linux.intel.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dan Williams <dan.j.williams@intel.com>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: David Woodhouse <dwmw2@infradead.org>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Josh Poimboeuf <jpoimboe@redhat.com>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: linux-kernel@vger.kernel.org
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/kernel/cpu/bugs.c | 28 +++++++++++-----------------
    1 file changed, 11 insertions(+), 17 deletions(-)

    --- a/arch/x86/kernel/cpu/bugs.c
    +++ b/arch/x86/kernel/cpu/bugs.c
    @@ -162,8 +162,7 @@ static enum spectre_v2_mitigation_cmd __
    if (cmdline_find_option_bool(boot_command_line, "nospectre_v2"))
    return SPECTRE_V2_CMD_NONE;
    else {
    - ret = cmdline_find_option(boot_command_line, "spectre_v2", arg,
    - sizeof(arg));
    + ret = cmdline_find_option(boot_command_line, "spectre_v2", arg, sizeof(arg));
    if (ret < 0)
    return SPECTRE_V2_CMD_AUTO;

    @@ -175,8 +174,7 @@ static enum spectre_v2_mitigation_cmd __
    }

    if (i >= ARRAY_SIZE(mitigation_options)) {
    - pr_err("unknown option (%s). Switching to AUTO select\n",
    - mitigation_options[i].option);
    + pr_err("unknown option (%s). Switching to AUTO select\n", mitigation_options[i].option);
    return SPECTRE_V2_CMD_AUTO;
    }
    }
    @@ -185,8 +183,7 @@ static enum spectre_v2_mitigation_cmd __
    cmd == SPECTRE_V2_CMD_RETPOLINE_AMD ||
    cmd == SPECTRE_V2_CMD_RETPOLINE_GENERIC) &&
    !IS_ENABLED(CONFIG_RETPOLINE)) {
    - pr_err("%s selected but not compiled in. Switching to AUTO select\n",
    - mitigation_options[i].option);
    + pr_err("%s selected but not compiled in. Switching to AUTO select\n", mitigation_options[i].option);
    return SPECTRE_V2_CMD_AUTO;
    }

    @@ -256,14 +253,14 @@ static void __init spectre_v2_select_mit
    goto retpoline_auto;
    break;
    }
    - pr_err("kernel not compiled with retpoline; no mitigation available!");
    + pr_err("Spectre mitigation: kernel not compiled with retpoline; no mitigation available!");
    return;

    retpoline_auto:
    if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD) {
    retpoline_amd:
    if (!boot_cpu_has(X86_FEATURE_LFENCE_RDTSC)) {
    - pr_err("LFENCE not serializing. Switching to generic retpoline\n");
    + pr_err("Spectre mitigation: LFENCE not serializing, switching to generic retpoline\n");
    goto retpoline_generic;
    }
    mode = retp_compiler() ? SPECTRE_V2_RETPOLINE_AMD :
    @@ -281,7 +278,7 @@ retpoline_auto:
    pr_info("%s\n", spectre_v2_strings[mode]);

    /*
    - * If neither SMEP or KPTI are available, there is a risk of
    + * If neither SMEP nor PTI are available, there is a risk of
    * hitting userspace addresses in the RSB after a context switch
    * from a shallow call stack to a deeper one. To prevent this fill
    * the entire RSB, even when using IBRS.
    @@ -295,21 +292,20 @@ retpoline_auto:
    if ((!boot_cpu_has(X86_FEATURE_PTI) &&
    !boot_cpu_has(X86_FEATURE_SMEP)) || is_skylake_era()) {
    setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
    - pr_info("Filling RSB on context switch\n");
    + pr_info("Spectre v2 mitigation: Filling RSB on context switch\n");
    }

    /* Initialize Indirect Branch Prediction Barrier if supported */
    if (boot_cpu_has(X86_FEATURE_IBPB)) {
    setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
    - pr_info("Enabling Indirect Branch Prediction Barrier\n");
    + pr_info("Spectre v2 mitigation: Enabling Indirect Branch Prediction Barrier\n");
    }
    }

    #undef pr_fmt

    #ifdef CONFIG_SYSFS
    -ssize_t cpu_show_meltdown(struct device *dev,
    - struct device_attribute *attr, char *buf)
    +ssize_t cpu_show_meltdown(struct device *dev, struct device_attribute *attr, char *buf)
    {
    if (!boot_cpu_has_bug(X86_BUG_CPU_MELTDOWN))
    return sprintf(buf, "Not affected\n");
    @@ -318,16 +314,14 @@ ssize_t cpu_show_meltdown(struct device
    return sprintf(buf, "Vulnerable\n");
    }

    -ssize_t cpu_show_spectre_v1(struct device *dev,
    - struct device_attribute *attr, char *buf)
    +ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr, char *buf)
    {
    if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V1))
    return sprintf(buf, "Not affected\n");
    return sprintf(buf, "Mitigation: __user pointer sanitization\n");
    }

    -ssize_t cpu_show_spectre_v2(struct device *dev,
    - struct device_attribute *attr, char *buf)
    +ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf)
    {
    if (!boot_cpu_has_bug(X86_BUG_SPECTRE_V2))
    return sprintf(buf, "Not affected\n");

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