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.
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