When we're building the compat VDSO we are building 32-bit code but in the context of a 64-bit kernel configuration.
To make this work we need to be careful in some places when using ifdefs to differentiate between CONFIG_PPC64 and __powerpc64__. CONFIG_PPC64 indicates the kernel we're building is 64-bit, but it doesn't tell us that we're currently building 64-bit code - we could be building 32-bit code for the compat VDSO. On the other hand __powerpc64__ tells us that we are currently building 64-bit code (and therefore we must also be building a 64-bit kernel). In the case of get_tb() we want to use the 32-bit code sequence regardless of whether the kernel we're building for is 64-bit or 32-bit, what matters is the word size of the current object. So we need to check __powerpc64__ to decide if we use mftb() or the mftbu()/mftb() sequence. For mftb() the logic for CPU_FTR_CELL_TB_BUG only makes sense if we're building 64-bit code, so guard that with a __powerpc64__ check. Signed-off-by: Christophe Leroy <christophe.le...@csgroup.eu> Signed-off-by: Michael Ellerman <m...@ellerman.id.au> --- arch/powerpc/include/asm/vdso/timebase.h | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) v14: new diff --git a/arch/powerpc/include/asm/vdso/timebase.h b/arch/powerpc/include/asm/vdso/timebase.h index ac6769b348c6..b558b07959ce 100644 --- a/arch/powerpc/include/asm/vdso/timebase.h +++ b/arch/powerpc/include/asm/vdso/timebase.h @@ -8,7 +8,11 @@ #include <asm/reg.h> -#if defined(CONFIG_PPC_CELL) || defined(CONFIG_E500) +/* + * We use __powerpc64__ here because we want the compat VDSO to use the 32-bit + * version below in the else case of the ifdef. + */ +#if defined(__powerpc64__) && (defined(CONFIG_PPC_CELL) || defined(CONFIG_E500)) #define mftb() ({unsigned long rval; \ asm volatile( \ "90: mfspr %0, %2;\n" \ @@ -49,7 +53,11 @@ static inline u64 get_tb(void) { unsigned int tbhi, tblo, tbhi2; - if (IS_ENABLED(CONFIG_PPC64)) + /* + * We use __powerpc64__ here not CONFIG_PPC64 because we want the compat + * VDSO to use the 32-bit compatible version in the while loop below. + */ + if (__is_defined(__powerpc64__)) return mftb(); do { -- 2.25.1