On Fri, Oct 18, 2024 at 03:11:38PM +0000, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@xxxxxxxx>
>
> Clang-19 and above sometimes end up with multiple copies of the large
> a6xx_hfi_msg_bw_table structure on the stack. The problem is that
> a6xx_hfi_send_bw_table() calls a number of device specific functions to
> fill the structure, but these create another copy of the structure on
> the stack which gets copied to the first.
>
> If the functions get inlined, that busts the warning limit:
>
> drivers/gpu/drm/msm/adreno/a6xx_hfi.c:631:12: error: stack frame size (1032) exceeds limit (1024) in 'a6xx_hfi_send_bw_table' [-Werror,-Wframe-larger-than]
Why does this warning says that the limit is 1024? 1024 bytes is too small, isn't it?
-Akhil.
>
> Mark all of them as 'noinline_for_stack' ensure we only have one copy
> of the structure per function.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> drivers/gpu/drm/msm/adreno/a6xx_hfi.c | 21 +++++++++++----------
> 1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> index cdb3f6e74d3e..5699e0420eb8 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_hfi.c
> @@ -259,7 +259,8 @@ static int a6xx_hfi_send_perf_table(struct a6xx_gmu *gmu)
> NULL, 0);
> }
>
> -static void a618_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +/* noinline to avoid having multiple copies of 'msg' on stack */
> +static noinline_for_stack void a618_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /* Send a single "off" entry since the 618 GMU doesn't do bus scaling */
> msg->bw_level_num = 1;
> @@ -287,7 +288,7 @@ static void a618_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a619_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a619_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> msg->bw_level_num = 13;
>
> @@ -346,7 +347,7 @@ static void a619_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[0][0] = 0x40000000;
> }
>
> -static void a640_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a640_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /*
> * Send a single "off" entry just to get things running
> @@ -385,7 +386,7 @@ static void a640_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][2] = 0x60000001;
> }
>
> -static void a650_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a650_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /*
> * Send a single "off" entry just to get things running
> @@ -416,7 +417,7 @@ static void a650_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a690_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a690_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /*
> * Send a single "off" entry just to get things running
> @@ -447,7 +448,7 @@ static void a690_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a660_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a660_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /*
> * Send a single "off" entry just to get things running
> @@ -478,7 +479,7 @@ static void a660_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void adreno_7c3_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void adreno_7c3_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /*
> * Send a single "off" entry just to get things running
> @@ -509,7 +510,7 @@ static void adreno_7c3_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a730_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a730_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> msg->bw_level_num = 12;
>
> @@ -565,7 +566,7 @@ static void a730_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a740_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a740_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> msg->bw_level_num = 1;
>
> @@ -590,7 +591,7 @@ static void a740_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> msg->cnoc_cmds_data[1][0] = 0x60000001;
> }
>
> -static void a6xx_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> +static noinline_for_stack void a6xx_build_bw_table(struct a6xx_hfi_msg_bw_table *msg)
> {
> /* Send a single "off" entry since the 630 GMU doesn't do bus scaling */
> msg->bw_level_num = 1;
> --
> 2.39.5
>
