linux-kernel - Re: [PATCH] cpufreq: amd-pstate: fix global sysfs attribute type

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Message-ID: <CAFqe=z+d2pi05KkOVw_LD00KHD-aX5tKVej5F6hc2wmUC9f_Yg@mail.gmail.com>
Date:   Mon, 7 Aug 2023 19:19:24 +0200
From:   Jannik Glückert <jannik.glueckert@...il.com>
To:     Thomas Weißschuh <linux@...ssschuh.net>
Cc:     Huang Rui <ray.huang@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        linux-kernel@...r.kernel.org, Bagas Sanjaya <bagasdotme@...il.com>,
        Linux LLVM Build Support <llvm@...ts.linux.dev>,
        Linux Power Management <linux-pm@...r.kernel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org
Subject: Re: [PATCH] cpufreq: amd-pstate: fix global sysfs attribute type

Hi Thomas,

thanks for the super quick response, your patch fixes the issue.

Best
Jannik

Am Mo., 7. Aug. 2023 um 08:37 Uhr schrieb Thomas Weißschuh
<linux@...ssschuh.net>:
>
> In commit 3666062b87ec ("cpufreq: amd-pstate: move to use bus_get_dev_root()")
> the "amd_pstate" attributes where moved from a dedicated kobject to the
> cpu root kobject.
> While the dedicated kobject expects to contain kobj_attributes the root
> kobject needs device_attributes.
>
> As the changed arguments are not used by the callbacks it works most of
> the time.
> However CFI will detect this issue:
>
> [ 4947.849350] CFI failure at dev_attr_show+0x24/0x60 (target: show_status+0x0/0x70; expected type: 0x8651b1de)
> ...
> [ 4947.849409] Call Trace:
> [ 4947.849410]  <TASK>
> [ 4947.849411]  ? __warn+0xcf/0x1c0
> [ 4947.849414]  ? dev_attr_show+0x24/0x60
> [ 4947.849415]  ? report_cfi_failure+0x4e/0x60
> [ 4947.849417]  ? handle_cfi_failure+0x14c/0x1d0
> [ 4947.849419]  ? __cfi_show_status+0x10/0x10
> [ 4947.849420]  ? handle_bug+0x4f/0x90
> [ 4947.849421]  ? exc_invalid_op+0x1a/0x60
> [ 4947.849422]  ? asm_exc_invalid_op+0x1a/0x20
> [ 4947.849424]  ? __cfi_show_status+0x10/0x10
> [ 4947.849425]  ? dev_attr_show+0x24/0x60
> [ 4947.849426]  sysfs_kf_seq_show+0xa6/0x110
> [ 4947.849433]  seq_read_iter+0x16c/0x4b0
> [ 4947.849436]  vfs_read+0x272/0x2d0
> [ 4947.849438]  ksys_read+0x72/0xe0
> [ 4947.849439]  do_syscall_64+0x76/0xb0
> [ 4947.849440]  ? do_user_addr_fault+0x252/0x650
> [ 4947.849442]  ? exc_page_fault+0x7a/0x1b0
> [ 4947.849443]  entry_SYSCALL_64_after_hwframe+0x72/0xdc
>
> Reported-by: Jannik Glückert <jannik.glueckert@...il.com>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217765
> Link: https://lore.kernel.org/lkml/c7f1bf9b-b183-bf6e-1cbb-d43f72494083@gmail.com/
> Fixes: 3666062b87ec ("cpufreq: amd-pstate: move to use bus_get_dev_root()")
> Cc: stable@...r.kernel.org
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
> Note:
>
> This was not tested with CFI as I don't have the toolchain available.
> Jannik, could you give it a spin?
> ---
>  drivers/cpufreq/amd-pstate.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/cpufreq/amd-pstate.c b/drivers/cpufreq/amd-pstate.c
> index 81fba0dcbee9..9a1e194d5cf8 100644
> --- a/drivers/cpufreq/amd-pstate.c
> +++ b/drivers/cpufreq/amd-pstate.c
> @@ -1012,8 +1012,8 @@ static int amd_pstate_update_status(const char *buf, size_t size)
>         return 0;
>  }
>
> -static ssize_t show_status(struct kobject *kobj,
> -                          struct kobj_attribute *attr, char *buf)
> +static ssize_t status_show(struct device *dev,
> +                          struct device_attribute *attr, char *buf)
>  {
>         ssize_t ret;
>
> @@ -1024,7 +1024,7 @@ static ssize_t show_status(struct kobject *kobj,
>         return ret;
>  }
>
> -static ssize_t store_status(struct kobject *a, struct kobj_attribute *b,
> +static ssize_t status_store(struct device *a, struct device_attribute *b,
>                             const char *buf, size_t count)
>  {
>         char *p = memchr(buf, '\n', count);
> @@ -1043,7 +1043,7 @@ cpufreq_freq_attr_ro(amd_pstate_lowest_nonlinear_freq);
>  cpufreq_freq_attr_ro(amd_pstate_highest_perf);
>  cpufreq_freq_attr_rw(energy_performance_preference);
>  cpufreq_freq_attr_ro(energy_performance_available_preferences);
> -define_one_global_rw(status);
> +static DEVICE_ATTR_RW(status);
>
>  static struct freq_attr *amd_pstate_attr[] = {
>         &amd_pstate_max_freq,
> @@ -1062,7 +1062,7 @@ static struct freq_attr *amd_pstate_epp_attr[] = {
>  };
>
>  static struct attribute *pstate_global_attributes[] = {
> -       &status.attr,
> +       &dev_attr_status.attr,
>         NULL
>  };
>
>
> ---
> base-commit: 52a93d39b17dc7eb98b6aa3edb93943248e03b2f
> change-id: 20230807-amd-pstate-cfi-8302498c54f5
>
> Best regards,
> --
> Thomas Weißschuh <linux@...ssschuh.net>
>