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Message-ID: <1jr07g25da.fsf@starbuckisacylon.baylibre.com>
Date: Tue, 12 Nov 2024 10:01:05 +0100
From: Jerome Brunet <jbrunet@...libre.com>
To: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>
Cc: Neil Armstrong <neil.armstrong@...aro.org>,  Michael Turquette
 <mturquette@...libre.com>,  Stephen Boyd <sboyd@...nel.org>,  Kevin Hilman
 <khilman@...libre.com>,  Martin Blumenstingl
 <martin.blumenstingl@...glemail.com>,  Jian Hu <jian.hu@...ogic.com>,
  Dmitry Rokosov <ddrokosov@...rdevices.ru>,  Yu Tu <yu.tu@...ogic.com>,
  chuan.liu@...ogic.com,  linux-amlogic@...ts.infradead.org,
  linux-clk@...r.kernel.org,  linux-arm-kernel@...ts.infradead.org,
  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] clk: meson: Fix children of ro_clk may be tampered with

On Mon 11 Nov 2024 at 17:37, Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org> wrote:

> From: Chuan Liu <chuan.liu@...ogic.com>
>
> When setting the rate of a clock using clk_regmap_divider_ro_ops, the
> rate of its children may be tampered with.
>
> Fixes: 84af914404db ("clk: meson: a1: add Amlogic A1 Peripherals clock controller driver")
> Fixes: 87173557d2f6 ("clk: meson: clk-pll: remove od parameters")
> Fixes: 085a4ea93d54 ("clk: meson: g12a: add peripheral clock controller")
> Fixes: 64aa7008e957 ("clk: meson: add a driver for the Meson8/8b/8m2 DDR clock controller")
> Fixes: 57b55c76aaf1 ("clk: meson: S4: add support for Amlogic S4 SoC peripheral clock controller")
> Fixes: e787c9c55eda ("clk: meson: S4: add support for Amlogic S4 SoC PLL clock driver")

Think about stable trying to pick up this ... 

> Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
> ---
> Background: During the execution of clk_set_rate(), the function 
> clk_core_round_rate_nolock() is called to calculate the matching rate
> and save it to 'core->new_rate'. At the same time, it recalculates and
> updates its 'child->newrate'. Finally, clk_change_rate() is called to
> set all 'new_rates'.
>
> In clk_regmap_divider_ro_ops, there is an implementation of
> 'determine_rate'. If a clock (name as 'ro_divider') that references
> clk_regmap_divider_ro_ops is not configured with CLK_DIVIDER_READ_ONLY,
> it will result in the calculation of an incorrect core->new_rate and
> potentially tamper with child->newrate, ultimately leading to the
> corruption of the rate for 'ro_divider's' children.

A slitghtly more simple way to put it, is that ro_ops have the regular
determine_rate function, so it can actually alter the rate.

That should be in the commit description, not where it will be dropped.

Requiring the flag in addition to ro_ops in redundant.
Plus, it is not the platform that should be fixed but the divider
driver.

Just put the content of the CLK_DIVIDER_READ_ONLY if clause into a
function, clk_regmap_div_ro_determine_rate(), and use it
- directly for ro_ops
- under if clause for regular ops.

> ---
>  drivers/clk/meson/a1-peripherals.c |  2 ++
>  drivers/clk/meson/axg.c            |  5 +++--
>  drivers/clk/meson/g12a.c           | 23 ++++++++++++++---------
>  drivers/clk/meson/gxbb.c           | 18 ++++++++++--------
>  drivers/clk/meson/meson8-ddr.c     |  2 +-
>  drivers/clk/meson/meson8b.c        |  4 +++-
>  drivers/clk/meson/s4-peripherals.c |  2 ++
>  drivers/clk/meson/s4-pll.c         |  2 +-
>  8 files changed, 36 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/clk/meson/a1-peripherals.c b/drivers/clk/meson/a1-peripherals.c
> index 7aa6abb2eb1f..eedf7c2bf970 100644
> --- a/drivers/clk/meson/a1-peripherals.c
> +++ b/drivers/clk/meson/a1-peripherals.c
> @@ -266,6 +266,7 @@ static struct clk_regmap sys_b_div = {
>  		.offset = SYS_CLK_CTRL0,
>  		.shift = 16,
>  		.width = 10,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sys_b_div",
> @@ -314,6 +315,7 @@ static struct clk_regmap sys_a_div = {
>  		.offset = SYS_CLK_CTRL0,
>  		.shift = 0,
>  		.width = 10,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sys_a_div",
> diff --git a/drivers/clk/meson/axg.c b/drivers/clk/meson/axg.c
> index 1b08daf579b2..eb86c4d10046 100644
> --- a/drivers/clk/meson/axg.c
> +++ b/drivers/clk/meson/axg.c
> @@ -71,7 +71,7 @@ static struct clk_regmap axg_fixed_pll = {
>  		.offset = HHI_MPLL_CNTL,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "fixed_pll",
> @@ -130,7 +130,7 @@ static struct clk_regmap axg_sys_pll = {
>  		.offset = HHI_SYS_PLL_CNTL,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sys_pll",
> @@ -471,6 +471,7 @@ static struct clk_regmap axg_mpll_prediv = {
>  		.offset = HHI_MPLL_CNTL5,
>  		.shift = 12,
>  		.width = 1,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "mpll_prediv",
> diff --git a/drivers/clk/meson/g12a.c b/drivers/clk/meson/g12a.c
> index d3539fe9f7af..c7c9fdfd021f 100644
> --- a/drivers/clk/meson/g12a.c
> +++ b/drivers/clk/meson/g12a.c
> @@ -76,7 +76,7 @@ static struct clk_regmap g12a_fixed_pll = {
>  		.offset = HHI_FIX_PLL_CNTL0,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "fixed_pll",
> @@ -443,6 +443,7 @@ static struct clk_regmap g12a_cpu_clk_mux1_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL0,
>  		.shift = 20,
>  		.width = 6,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpu_clk_dyn1_div",
> @@ -627,6 +628,7 @@ static struct clk_regmap g12b_cpub_clk_mux1_div = {
>  		.offset = HHI_SYS_CPUB_CLK_CNTL,
>  		.shift = 20,
>  		.width = 6,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpub_clk_dyn1_div",
> @@ -746,6 +748,7 @@ static struct clk_regmap sm1_dsu_clk_mux0_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL5,
>  		.shift = 4,
>  		.width = 6,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "dsu_clk_dyn0_div",
> @@ -781,6 +784,7 @@ static struct clk_regmap sm1_dsu_clk_mux1_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL5,
>  		.shift = 20,
>  		.width = 6,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "dsu_clk_dyn1_div",
> @@ -1198,7 +1202,7 @@ static struct clk_regmap g12a_cpu_clk_apb_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL1,
>  		.shift = 3,
>  		.width = 3,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpu_clk_apb_div",
> @@ -1232,7 +1236,7 @@ static struct clk_regmap g12a_cpu_clk_atb_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL1,
>  		.shift = 6,
>  		.width = 3,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpu_clk_atb_div",
> @@ -1266,7 +1270,7 @@ static struct clk_regmap g12a_cpu_clk_axi_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL1,
>  		.shift = 9,
>  		.width = 3,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpu_clk_axi_div",
> @@ -1300,7 +1304,7 @@ static struct clk_regmap g12a_cpu_clk_trace_div = {
>  		.offset = HHI_SYS_CPU_CLK_CNTL1,
>  		.shift = 20,
>  		.width = 3,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "cpu_clk_trace_div",
> @@ -1736,7 +1740,7 @@ static struct clk_regmap sm1_gp1_pll = {
>  		.shift = 16,
>  		.width = 3,
>  		.flags = (CLK_DIVIDER_POWER_OF_TWO |
> -			  CLK_DIVIDER_ROUND_CLOSEST),
> +			  CLK_DIVIDER_ROUND_CLOSEST | CLK_DIVIDER_READ_ONLY),
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "gp1_pll",
> @@ -1999,7 +2003,7 @@ static struct clk_regmap g12a_hdmi_pll_od = {
>  		.offset = HHI_HDMI_PLL_CNTL0,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od",
> @@ -2017,7 +2021,7 @@ static struct clk_regmap g12a_hdmi_pll_od2 = {
>  		.offset = HHI_HDMI_PLL_CNTL0,
>  		.shift = 18,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od2",
> @@ -2035,7 +2039,7 @@ static struct clk_regmap g12a_hdmi_pll = {
>  		.offset = HHI_HDMI_PLL_CNTL0,
>  		.shift = 20,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll",
> @@ -4048,6 +4052,7 @@ static struct clk_regmap g12a_ts_div = {
>  		.offset = HHI_TS_CLK_CNTL,
>  		.shift = 0,
>  		.width = 8,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "ts_div",
> diff --git a/drivers/clk/meson/gxbb.c b/drivers/clk/meson/gxbb.c
> index 262c318edbd5..e2b419100e0c 100644
> --- a/drivers/clk/meson/gxbb.c
> +++ b/drivers/clk/meson/gxbb.c
> @@ -131,7 +131,7 @@ static struct clk_regmap gxbb_fixed_pll = {
>  		.offset = HHI_MPLL_CNTL,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "fixed_pll",
> @@ -267,7 +267,7 @@ static struct clk_regmap gxbb_hdmi_pll_od = {
>  		.offset = HHI_HDMI_PLL_CNTL2,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od",
> @@ -285,7 +285,7 @@ static struct clk_regmap gxbb_hdmi_pll_od2 = {
>  		.offset = HHI_HDMI_PLL_CNTL2,
>  		.shift = 22,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od2",
> @@ -303,7 +303,7 @@ static struct clk_regmap gxbb_hdmi_pll = {
>  		.offset = HHI_HDMI_PLL_CNTL2,
>  		.shift = 18,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll",
> @@ -321,7 +321,7 @@ static struct clk_regmap gxl_hdmi_pll_od = {
>  		.offset = HHI_HDMI_PLL_CNTL + 8,
>  		.shift = 21,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od",
> @@ -339,7 +339,7 @@ static struct clk_regmap gxl_hdmi_pll_od2 = {
>  		.offset = HHI_HDMI_PLL_CNTL + 8,
>  		.shift = 23,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll_od2",
> @@ -357,7 +357,7 @@ static struct clk_regmap gxl_hdmi_pll = {
>  		.offset = HHI_HDMI_PLL_CNTL + 8,
>  		.shift = 19,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "hdmi_pll",
> @@ -413,7 +413,7 @@ static struct clk_regmap gxbb_sys_pll = {
>  		.offset = HHI_SYS_PLL_CNTL,
>  		.shift = 10,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sys_pll",
> @@ -703,6 +703,7 @@ static struct clk_regmap gxbb_mpll_prediv = {
>  		.offset = HHI_MPLL_CNTL5,
>  		.shift = 12,
>  		.width = 1,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "mpll_prediv",
> @@ -911,6 +912,7 @@ static struct clk_regmap gxbb_mpeg_clk_div = {
>  		.offset = HHI_MPEG_CLK_CNTL,
>  		.shift = 0,
>  		.width = 7,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "mpeg_clk_div",
> diff --git a/drivers/clk/meson/meson8-ddr.c b/drivers/clk/meson/meson8-ddr.c
> index 4b73ea244b63..950f323072fb 100644
> --- a/drivers/clk/meson/meson8-ddr.c
> +++ b/drivers/clk/meson/meson8-ddr.c
> @@ -65,7 +65,7 @@ static struct clk_regmap meson8_ddr_pll = {
>  		.offset = AM_DDR_PLL_CNTL,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "ddr_pll",
> diff --git a/drivers/clk/meson/meson8b.c b/drivers/clk/meson/meson8b.c
> index e4b474c5f86c..4dba11c0ab7e 100644
> --- a/drivers/clk/meson/meson8b.c
> +++ b/drivers/clk/meson/meson8b.c
> @@ -104,7 +104,7 @@ static struct clk_regmap meson8b_fixed_pll = {
>  		.offset = HHI_MPLL_CNTL,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "fixed_pll",
> @@ -457,6 +457,7 @@ static struct clk_regmap meson8b_mpll_prediv = {
>  		.offset = HHI_MPLL_CNTL5,
>  		.shift = 12,
>  		.width = 1,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "mpll_prediv",
> @@ -635,6 +636,7 @@ static struct clk_regmap meson8b_mpeg_clk_div = {
>  		.offset = HHI_MPEG_CLK_CNTL,
>  		.shift = 0,
>  		.width = 7,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "mpeg_clk_div",
> diff --git a/drivers/clk/meson/s4-peripherals.c b/drivers/clk/meson/s4-peripherals.c
> index c930cf0614a0..470431355e25 100644
> --- a/drivers/clk/meson/s4-peripherals.c
> +++ b/drivers/clk/meson/s4-peripherals.c
> @@ -175,6 +175,7 @@ static struct clk_regmap s4_sysclk_b_div = {
>  		.offset = CLKCTRL_SYS_CLK_CTRL0,
>  		.shift = 16,
>  		.width = 10,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sysclk_b_div",
> @@ -221,6 +222,7 @@ static struct clk_regmap s4_sysclk_a_div = {
>  		.offset = CLKCTRL_SYS_CLK_CTRL0,
>  		.shift = 0,
>  		.width = 10,
> +		.flags = CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "sysclk_a_div",
> diff --git a/drivers/clk/meson/s4-pll.c b/drivers/clk/meson/s4-pll.c
> index d8e621e79428..5dc051afc06a 100644
> --- a/drivers/clk/meson/s4-pll.c
> +++ b/drivers/clk/meson/s4-pll.c
> @@ -72,7 +72,7 @@ static struct clk_regmap s4_fixed_pll = {
>  		.offset = ANACTRL_FIXPLL_CTRL0,
>  		.shift = 16,
>  		.width = 2,
> -		.flags = CLK_DIVIDER_POWER_OF_TWO,
> +		.flags = CLK_DIVIDER_POWER_OF_TWO | CLK_DIVIDER_READ_ONLY,
>  	},
>  	.hw.init = &(struct clk_init_data){
>  		.name = "fixed_pll",
>
> ---
> base-commit: 664988eb47dd2d6ae1d9e4188ec91832562f8f26
> change-id: 20241111-fix_childclk_of_roclk_has_been_tampered_with-61dbcc623746
>
> Best regards,

-- 
Jerome

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