Re: [PATCH] tuners: tda8290: reduce stack usage with kasan

From: Michael Ira Krufky
Date: Mon Dec 11 2017 - 10:09:44 EST

On Mon, Dec 11, 2017 at 7:06 AM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> With CONFIG_KASAN enabled, we get a relatively large stack frame in one function
>
> drivers/media/tuners/tda8290.c: In function 'tda8290_set_params':
> drivers/media/tuners/tda8290.c:310:1: warning: the frame size of 1520 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>
> With CONFIG_KASAN_EXTRA this goes up to
>
> drivers/media/tuners/tda8290.c: In function 'tda8290_set_params':
> drivers/media/tuners/tda8290.c:310:1: error: the frame size of 3200 bytes is larger than 3072 bytes [-Werror=frame-larger-than=]
>
> We can significantly reduce this by marking local arrays as 'static const', and
> this should result in better compiled code for everyone.
>
> I have another patch for the same symptom to patch tuner_i2c_xfer_*, and we
> actually want both of them.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>

Thank you, Arnd.

Reviewed-by: Michael Ira Krufky <mkrufky@xxxxxxxxxxx>


> ---
> drivers/media/tuners/tda8290.c | 76 ++++++++++++++++++++++--------------------
> 1 file changed, 39 insertions(+), 37 deletions(-)
>
> diff --git a/drivers/media/tuners/tda8290.c b/drivers/media/tuners/tda8290.c
> index a59c567c55d6..19854221b72d 100644
> --- a/drivers/media/tuners/tda8290.c
> +++ b/drivers/media/tuners/tda8290.c
> @@ -63,8 +63,8 @@ static int tda8290_i2c_bridge(struct dvb_frontend *fe, int close)
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
>
> - unsigned char enable[2] = { 0x21, 0xC0 };
> - unsigned char disable[2] = { 0x21, 0x00 };
> + static unsigned char enable[2] = { 0x21, 0xC0 };
> + static unsigned char disable[2] = { 0x21, 0x00 };
> unsigned char *msg;
>
> if (close) {
> @@ -84,9 +84,9 @@ static int tda8295_i2c_bridge(struct dvb_frontend *fe, int close)
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
>
> - unsigned char enable[2] = { 0x45, 0xc1 };
> - unsigned char disable[2] = { 0x46, 0x00 };
> - unsigned char buf[3] = { 0x45, 0x01, 0x00 };
> + static unsigned char enable[2] = { 0x45, 0xc1 };
> + static unsigned char disable[2] = { 0x46, 0x00 };
> + static unsigned char buf[3] = { 0x45, 0x01, 0x00 };
> unsigned char *msg;
>
> if (close) {
> @@ -178,24 +178,24 @@ static void tda8290_set_params(struct dvb_frontend *fe,
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
>
> - unsigned char soft_reset[] = { 0x00, 0x00 };
> + static unsigned char soft_reset[] = { 0x00, 0x00 };
> unsigned char easy_mode[] = { 0x01, priv->tda8290_easy_mode };
> - unsigned char expert_mode[] = { 0x01, 0x80 };
> - unsigned char agc_out_on[] = { 0x02, 0x00 };
> - unsigned char gainset_off[] = { 0x28, 0x14 };
> - unsigned char if_agc_spd[] = { 0x0f, 0x88 };
> - unsigned char adc_head_6[] = { 0x05, 0x04 };
> - unsigned char adc_head_9[] = { 0x05, 0x02 };
> - unsigned char adc_head_12[] = { 0x05, 0x01 };
> - unsigned char pll_bw_nom[] = { 0x0d, 0x47 };
> - unsigned char pll_bw_low[] = { 0x0d, 0x27 };
> - unsigned char gainset_2[] = { 0x28, 0x64 };
> - unsigned char agc_rst_on[] = { 0x0e, 0x0b };
> - unsigned char agc_rst_off[] = { 0x0e, 0x09 };
> - unsigned char if_agc_set[] = { 0x0f, 0x81 };
> - unsigned char addr_adc_sat = 0x1a;
> - unsigned char addr_agc_stat = 0x1d;
> - unsigned char addr_pll_stat = 0x1b;
> + static unsigned char expert_mode[] = { 0x01, 0x80 };
> + static unsigned char agc_out_on[] = { 0x02, 0x00 };
> + static unsigned char gainset_off[] = { 0x28, 0x14 };
> + static unsigned char if_agc_spd[] = { 0x0f, 0x88 };
> + static unsigned char adc_head_6[] = { 0x05, 0x04 };
> + static unsigned char adc_head_9[] = { 0x05, 0x02 };
> + static unsigned char adc_head_12[] = { 0x05, 0x01 };
> + static unsigned char pll_bw_nom[] = { 0x0d, 0x47 };
> + static unsigned char pll_bw_low[] = { 0x0d, 0x27 };
> + static unsigned char gainset_2[] = { 0x28, 0x64 };
> + static unsigned char agc_rst_on[] = { 0x0e, 0x0b };
> + static unsigned char agc_rst_off[] = { 0x0e, 0x09 };
> + static unsigned char if_agc_set[] = { 0x0f, 0x81 };
> + static unsigned char addr_adc_sat = 0x1a;
> + static unsigned char addr_agc_stat = 0x1d;
> + static unsigned char addr_pll_stat = 0x1b;
> unsigned char adc_sat, agc_stat,
> pll_stat;
> int i;
> @@ -468,9 +468,9 @@ static void tda8290_standby(struct dvb_frontend *fe)
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
>
> - unsigned char cb1[] = { 0x30, 0xD0 };
> - unsigned char tda8290_standby[] = { 0x00, 0x02 };
> - unsigned char tda8290_agc_tri[] = { 0x02, 0x20 };
> + static unsigned char cb1[] = { 0x30, 0xD0 };
> + static unsigned char tda8290_standby[] = { 0x00, 0x02 };
> + static unsigned char tda8290_agc_tri[] = { 0x02, 0x20 };
> struct i2c_msg msg = {.addr = priv->tda827x_addr, .flags=0, .buf=cb1, .len = 2};
>
> if (fe->ops.analog_ops.i2c_gate_ctrl)
> @@ -495,9 +495,9 @@ static void tda8290_init_if(struct dvb_frontend *fe)
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
>
> - unsigned char set_VS[] = { 0x30, 0x6F };
> - unsigned char set_GP00_CF[] = { 0x20, 0x01 };
> - unsigned char set_GP01_CF[] = { 0x20, 0x0B };
> + static unsigned char set_VS[] = { 0x30, 0x6F };
> + static unsigned char set_GP00_CF[] = { 0x20, 0x01 };
> + static unsigned char set_GP01_CF[] = { 0x20, 0x0B };
>
> if ((priv->cfg.config == TDA8290_LNA_GP0_HIGH_ON) ||
> (priv->cfg.config == TDA8290_LNA_GP0_HIGH_OFF))
> @@ -539,10 +539,12 @@ static void tda8295_init_if(struct dvb_frontend *fe)
> static void tda8290_init_tuner(struct dvb_frontend *fe)
> {
> struct tda8290_priv *priv = fe->analog_demod_priv;
> - unsigned char tda8275_init[] = { 0x00, 0x00, 0x00, 0x40, 0xdC, 0x04, 0xAf,
> - 0x3F, 0x2A, 0x04, 0xFF, 0x00, 0x00, 0x40 };
> - unsigned char tda8275a_init[] = { 0x00, 0x00, 0x00, 0x00, 0xdC, 0x05, 0x8b,
> - 0x0c, 0x04, 0x20, 0xFF, 0x00, 0x00, 0x4b };
> + static unsigned char tda8275_init[] =
> + { 0x00, 0x00, 0x00, 0x40, 0xdC, 0x04, 0xAf,
> + 0x3F, 0x2A, 0x04, 0xFF, 0x00, 0x00, 0x40 };
> + static unsigned char tda8275a_init[] =
> + { 0x00, 0x00, 0x00, 0x00, 0xdC, 0x05, 0x8b,
> + 0x0c, 0x04, 0x20, 0xFF, 0x00, 0x00, 0x4b };
> struct i2c_msg msg = {.addr = priv->tda827x_addr, .flags=0,
> .buf=tda8275_init, .len = 14};
> if (priv->ver & TDA8275A)
> @@ -834,11 +836,11 @@ int tda829x_probe(struct i2c_adapter *i2c_adap, u8 i2c_addr)
> .addr = i2c_addr,
> };
>
> - unsigned char soft_reset[] = { 0x00, 0x00 };
> - unsigned char easy_mode_b[] = { 0x01, 0x02 };
> - unsigned char easy_mode_g[] = { 0x01, 0x04 };
> - unsigned char restore_9886[] = { 0x00, 0xd6, 0x30 };
> - unsigned char addr_dto_lsb = 0x07;
> + static unsigned char soft_reset[] = { 0x00, 0x00 };
> + static unsigned char easy_mode_b[] = { 0x01, 0x02 };
> + static unsigned char easy_mode_g[] = { 0x01, 0x04 };
> + static unsigned char restore_9886[] = { 0x00, 0xd6, 0x30 };
> + static unsigned char addr_dto_lsb = 0x07;
> unsigned char data;
> #define PROBE_BUFFER_SIZE 8
> unsigned char buf[PROBE_BUFFER_SIZE];
> --
> 2.9.0
>