On Mon, Mar 15, 2021 at 3:04 PM gregkh@linuxfoundation.org wrote:
From: Greg Kroah-Hartman gregkh@linuxfoundation.org
From: Christophe Leroy christophe.leroy@csgroup.eu
commit bd73758803c2eedc037c2268b65a19542a832594 upstream.
Add stub instances of enable_kernel_vsx() and disable_kernel_vsx() when CONFIG_VSX is not set, to avoid following build failure.
Please note that this is not sufficient, and will just turn the build error in another, different build error. Waiting for the subsequent fix to enter v5.12-rc4... https://lore.kernel.org/lkml/2c123f94-ceae-80c0-90e2-21909795eb76@csgroup.eu...
CC [M] drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o In file included from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services_types.h:29, from ./drivers/gpu/drm/amd/amdgpu/../display/dc/dm_services.h:37, from drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:27: drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c: In function 'dcn_bw_apply_registry_override': ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:64:3: error: implicit declaration of function 'enable_kernel_vsx'; did you mean 'enable_kernel_fp'? [-Werror=implicit-function-declaration] 64 | enable_kernel_vsx(); \ | ^~~~~~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:640:2: note: in expansion of macro 'DC_FP_START' 640 | DC_FP_START(); | ^~~~~~~~~~~ ./drivers/gpu/drm/amd/amdgpu/../display/dc/os_types.h:75:3: error: implicit declaration of function 'disable_kernel_vsx'; did you mean 'disable_kernel_fp'? [-Werror=implicit-function-declaration] 75 | disable_kernel_vsx(); \ | ^~~~~~~~~~~~~~~~~~ drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.c:676:2: note: in expansion of macro 'DC_FP_END' 676 | DC_FP_END(); | ^~~~~~~~~ cc1: some warnings being treated as errors make[5]: *** [drivers/gpu/drm/amd/amdgpu/../display/dc/calcs/dcn_calcs.o] Error 1
This works because the caller is checking if VSX is available using cpu_has_feature():
#define DC_FP_START() { \ if (cpu_has_feature(CPU_FTR_VSX_COMP)) { \ preempt_disable(); \ enable_kernel_vsx(); \ } else if (cpu_has_feature(CPU_FTR_ALTIVEC_COMP)) { \ preempt_disable(); \ enable_kernel_altivec(); \ } else if (!cpu_has_feature(CPU_FTR_FPU_UNAVAILABLE)) { \ preempt_disable(); \ enable_kernel_fp(); \ } \
When CONFIG_VSX is not selected, cpu_has_feature(CPU_FTR_VSX_COMP) constant folds to 'false' so the call to enable_kernel_vsx() is discarded and the build succeeds.
Fixes: 16a9dea110a6 ("amdgpu: Enable initial DCN support on POWER") Cc: stable@vger.kernel.org # v5.6+ Reported-by: Geert Uytterhoeven geert@linux-m68k.org Reported-by: kernel test robot lkp@intel.com Signed-off-by: Christophe Leroy christophe.leroy@csgroup.eu [mpe: Incorporate some discussion comments into the change log] Signed-off-by: Michael Ellerman mpe@ellerman.id.au Link: https://lore.kernel.org/r/8d7d285a027e9d21f5ff7f850fa71a2655b0c4af.161527917... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
arch/powerpc/include/asm/switch_to.h | 10 ++++++++++ 1 file changed, 10 insertions(+)
--- a/arch/powerpc/include/asm/switch_to.h +++ b/arch/powerpc/include/asm/switch_to.h @@ -71,6 +71,16 @@ static inline void disable_kernel_vsx(vo { msr_check_and_clear(MSR_FP|MSR_VEC|MSR_VSX); } +#else +static inline void enable_kernel_vsx(void) +{
BUILD_BUG();+}
+static inline void disable_kernel_vsx(void) +{
BUILD_BUG();+} #endif
#ifdef CONFIG_SPE
Gr{oetje,eeting}s,
Geert