On Thu, Jul 13, 2017 at 5:55 PM, Ram Pai <linuxram@xxxxxxxxxx> wrote: > On Wed, Jul 12, 2017 at 03:26:01PM +1000, Balbir Singh wrote: >> On Wed, 5 Jul 2017 14:21:52 -0700 >> Ram Pai <linuxram@xxxxxxxxxx> wrote: >> >> > Implements helper functions to read and write the key related >> > registers; AMR, IAMR, UAMOR. >> > >> > AMR register tracks the read,write permission of a key >> > IAMR register tracks the execute permission of a key >> > UAMOR register enables and disables a key >> > >> > Signed-off-by: Ram Pai <linuxram@xxxxxxxxxx> >> > --- >> > arch/powerpc/include/asm/book3s/64/pgtable.h | 60 ++++++++++++++++++++++++++ >> > 1 files changed, 60 insertions(+), 0 deletions(-) >> > >> > diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h >> > index 85bc987..435d6a7 100644 >> > --- a/arch/powerpc/include/asm/book3s/64/pgtable.h >> > +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h >> > @@ -428,6 +428,66 @@ static inline void huge_ptep_set_wrprotect(struct mm_struct *mm, >> > pte_update(mm, addr, ptep, 0, _PAGE_PRIVILEGED, 1); >> > } >> > >> > +#ifdef CONFIG_PPC64_MEMORY_PROTECTION_KEYS >> > + >> > +#include <asm/reg.h> >> > +static inline u64 read_amr(void) >> > +{ >> > + return mfspr(SPRN_AMR); >> > +} >> > +static inline void write_amr(u64 value) >> > +{ >> > + mtspr(SPRN_AMR, value); >> > +} >> > +static inline u64 read_iamr(void) >> > +{ >> > + return mfspr(SPRN_IAMR); >> > +} >> > +static inline void write_iamr(u64 value) >> > +{ >> > + mtspr(SPRN_IAMR, value); >> > +} >> > +static inline u64 read_uamor(void) >> > +{ >> > + return mfspr(SPRN_UAMOR); >> > +} >> > +static inline void write_uamor(u64 value) >> > +{ >> > + mtspr(SPRN_UAMOR, value); >> > +} >> > + >> > +#else /* CONFIG_PPC64_MEMORY_PROTECTION_KEYS */ >> > + >> > +static inline u64 read_amr(void) >> > +{ >> > + WARN(1, "%s called with MEMORY PROTECTION KEYS disabled\n", __func__); >> > + return -1; >> > +} >> >> Why do we need to have a version here if we are going to WARN(), why not >> let the compilation fail if called from outside of CONFIG_PPC64_MEMORY_PROTECTION_KEYS? >> Is that the intention? > > I did not want to stop someone; kernel module for example, from calling > these interfaces from outside the pkey domain. > > Either way can be argued to be correct, I suppose. Nope, build failures are better than run time failures, otherwise the kernel will split its guts warning and warning here. Balbir Singh. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>