Le 15/03/2021 à 15:15, Geert Uytterhoeven a écrit :
On Mon, Mar 15, 2021 at 3:04 PM <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
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.
Not exactly, the fix is sufficient in most case, it is only with ancient versions of gcc (eg 4.9) or
with CONFIG_CC_OPTIMISE_FOR_SIZE that we now get a build bug. Building with gcc 10 now works.
Waiting for the subsequent fix to enter v5.12-rc4...
https://lore.kernel.org/lkml/2c123f94-ceae-80c0-90e2-21909795eb76@xxxxxxxxxx/
This has now landed in mainline as commit eed5fae00593ab9d261a0c1ffc1bdb786a87a55a see
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/arch/powerpc/include/asm/cpu_has_feature.h?h=v5.12-rc4&id=eed5fae00593ab9d261a0c1ffc1bdb786a87a55a
Christophe
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@xxxxxxxxxxxxxxx # v5.6+
Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
[mpe: Incorporate some discussion comments into the change log]
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/8d7d285a027e9d21f5ff7f850fa71a2655b0c4af.1615279170.git.christophe.leroy@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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
