| Message ID | 20220311005742.1060992-6-ira.weiny@intel.com (mailing list archive) |
|---|---|
| State | Handled Elsewhere, archived |
| Headers | show |
| Series | Pkey User clean up patches | expand |
| Context | Check | Description |
|---|---|---|
| snowpatch_ozlabs/github-powerpc_ppctests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_selftests | success | Successfully ran 8 jobs. |
| snowpatch_ozlabs/github-powerpc_sparse | success | Successfully ran 4 jobs. |
| snowpatch_ozlabs/github-powerpc_kernel_qemu | success | Successfully ran 24 jobs. |
| snowpatch_ozlabs/github-powerpc_clang | success | Successfully ran 7 jobs. |
On 3/10/22 16:57, ira.weiny@intel.com wrote: > From: Ira Weiny <ira.weiny@intel.com> > > The number of pkeys supported on x86 and powerpc are much smaller than a > u16 value can hold. It is desirable to standardize on the type for > pkeys. powerpc currently supports the most pkeys at 32. u8 is plenty > large for that. > > Standardize on the pkey types by changing u16 to u8. How widely was this intended to "standardize" things? Looks like it may have missed a few spots. Also if we're worried about the type needing to change or with the wrong type being used, I guess we could just to a pkey_t typedef.
On Mon, Mar 14, 2022 at 04:49:12PM -0700, Dave Hansen wrote: > On 3/10/22 16:57, ira.weiny@intel.com wrote: > > From: Ira Weiny <ira.weiny@intel.com> > > > > The number of pkeys supported on x86 and powerpc are much smaller than a > > u16 value can hold. It is desirable to standardize on the type for > > pkeys. powerpc currently supports the most pkeys at 32. u8 is plenty > > large for that. > > > > Standardize on the pkey types by changing u16 to u8. > > How widely was this intended to "standardize" things? Looks like it may > have missed a few spots. Sorry I think the commit message is misleading you. The justification of u8 as the proper type is that no arch has a need for more than 255 pkeys. This specific patch was intended to only change x86. Per that goal I don't see any other places in x86 which uses u16 after this patch. $ git grep u16 arch/x86 | grep key arch/x86/events/intel/uncore_discovery.c: const u16 *type_id = key; arch/x86/include/asm/intel_pconfig.h: u16 keyid; arch/x86/include/asm/mmu.h: u16 pkey_allocation_map; arch/x86/include/asm/pkeys.h: u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1); > > Also if we're worried about the type needing to change or with the wrong > type being used, I guess we could just to a pkey_t typedef. I'm not 'worried' about it. But I do think it makes the code cleaner and more self documenting. Ira
On 3/15/22 08:53, Ira Weiny wrote: > On Mon, Mar 14, 2022 at 04:49:12PM -0700, Dave Hansen wrote: >> On 3/10/22 16:57, ira.weiny@intel.com wrote: >>> From: Ira Weiny <ira.weiny@intel.com> >>> >>> The number of pkeys supported on x86 and powerpc are much smaller than a >>> u16 value can hold. It is desirable to standardize on the type for >>> pkeys. powerpc currently supports the most pkeys at 32. u8 is plenty >>> large for that. >>> >>> Standardize on the pkey types by changing u16 to u8. >> >> How widely was this intended to "standardize" things? Looks like it may >> have missed a few spots. > > Sorry I think the commit message is misleading you. The justification of u8 as > the proper type is that no arch has a need for more than 255 pkeys. > > This specific patch was intended to only change x86. Per that goal I don't see > any other places in x86 which uses u16 after this patch. > > $ git grep u16 arch/x86 | grep key > arch/x86/events/intel/uncore_discovery.c: const u16 *type_id = key; > arch/x86/include/asm/intel_pconfig.h: u16 keyid; > arch/x86/include/asm/mmu.h: u16 pkey_allocation_map; > arch/x86/include/asm/pkeys.h: u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1); I was also looking at the generic mm code. >> Also if we're worried about the type needing to changY or with the wrong >> type being used, I guess we could just to a pkey_t typedef. > > I'm not 'worried' about it. But I do think it makes the code cleaner and more > self documenting. Yeah, consistency is good. Do you mind taking a look at how a pkey_t would look, and also seeing how much core mm code should use it?
On Tue, Mar 15, 2022 at 09:03:26AM -0700, Dave Hansen wrote: > On 3/15/22 08:53, Ira Weiny wrote: > > On Mon, Mar 14, 2022 at 04:49:12PM -0700, Dave Hansen wrote: > >> On 3/10/22 16:57, ira.weiny@intel.com wrote: > >>> From: Ira Weiny <ira.weiny@intel.com> > >>> > >>> The number of pkeys supported on x86 and powerpc are much smaller than a > >>> u16 value can hold. It is desirable to standardize on the type for > >>> pkeys. powerpc currently supports the most pkeys at 32. u8 is plenty > >>> large for that. > >>> > >>> Standardize on the pkey types by changing u16 to u8. > >> > >> How widely was this intended to "standardize" things? Looks like it may > >> have missed a few spots. > > > > Sorry I think the commit message is misleading you. The justification of u8 as > > the proper type is that no arch has a need for more than 255 pkeys. > > > > This specific patch was intended to only change x86. Per that goal I don't see > > any other places in x86 which uses u16 after this patch. > > > > $ git grep u16 arch/x86 | grep key > > arch/x86/events/intel/uncore_discovery.c: const u16 *type_id = key; > > arch/x86/include/asm/intel_pconfig.h: u16 keyid; > > arch/x86/include/asm/mmu.h: u16 pkey_allocation_map; > > arch/x86/include/asm/pkeys.h: u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1); > > I was also looking at the generic mm code. Ah yea that needs to be sorted out too I think. > > >> Also if we're worried about the type needing to changY or with the wrong > >> type being used, I guess we could just to a pkey_t typedef. > > > > I'm not 'worried' about it. But I do think it makes the code cleaner and more > > self documenting. > > Yeah, consistency is good. Do you mind taking a look at how a pkey_t > would look, and also seeing how much core mm code should use it? I don't mind at all. Ira
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 8a9432fb3802..cb89f1224d8a 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -1357,7 +1357,7 @@ static inline pmd_t pmd_swp_clear_uffd_wp(pmd_t pmd) } #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */ -static inline u16 pte_flags_pkey(unsigned long pte_flags) +static inline u8 pte_flags_pkey(unsigned long pte_flags) { #ifdef CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS /* ifdef to avoid doing 59-bit shift on 32-bit values */ @@ -1367,7 +1367,7 @@ static inline u16 pte_flags_pkey(unsigned long pte_flags) #endif } -static inline bool __pkru_allows_pkey(u16 pkey, bool write) +static inline bool __pkru_allows_pkey(u8 pkey, bool write) { u32 pkru = read_pkru(); diff --git a/arch/x86/include/asm/pkru.h b/arch/x86/include/asm/pkru.h index 74f0a2d34ffd..06d088f06229 100644 --- a/arch/x86/include/asm/pkru.h +++ b/arch/x86/include/asm/pkru.h @@ -16,13 +16,13 @@ extern u32 init_pkru_value; #define pkru_get_init_value() 0 #endif -static inline bool __pkru_allows_read(u32 pkru, u16 pkey) +static inline bool __pkru_allows_read(u32 pkru, u8 pkey) { int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY; return !(pkru & (PKRU_AD_BIT << pkru_pkey_bits)); } -static inline bool __pkru_allows_write(u32 pkru, u16 pkey) +static inline bool __pkru_allows_write(u32 pkru, u8 pkey) { int pkru_pkey_bits = pkey * PKRU_BITS_PER_PKEY; /*