On 4/14/21 11:40 AM, Christophe Leroy wrote: > > > Le 14/04/2021 à 07:59, Anshuman Khandual a écrit : >> >> >> On 4/14/21 10:52 AM, Christophe Leroy wrote: >>> >>> >>> Le 14/04/2021 à 04:54, Anshuman Khandual a écrit : >>>> Currently most platforms define FIRST_USER_ADDRESS as 0UL duplicating the >>>> same code all over. Instead define a new option ARCH_HAS_FIRST_USER_ADDRESS >>>> for those platforms which would override generic default FIRST_USER_ADDRESS >>>> value 0UL. This makes it much cleaner with reduced code. >>>> >>>> Cc: linux-alpha@xxxxxxxxxxxxxxx >>>> Cc: linux-snps-arc@xxxxxxxxxxxxxxxxxxx >>>> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx >>>> Cc: linux-csky@xxxxxxxxxxxxxxx >>>> Cc: linux-hexagon@xxxxxxxxxxxxxxx >>>> Cc: linux-ia64@xxxxxxxxxxxxxxx >>>> Cc: linux-m68k@xxxxxxxxxxxxxxxxxxxx >>>> Cc: linux-mips@xxxxxxxxxxxxxxx >>>> Cc: openrisc@xxxxxxxxxxxxxxxxxxxx >>>> Cc: linux-parisc@xxxxxxxxxxxxxxx >>>> Cc: linuxppc-dev@xxxxxxxxxxxxxxxx >>>> Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx >>>> Cc: linux-s390@xxxxxxxxxxxxxxx >>>> Cc: linux-sh@xxxxxxxxxxxxxxx >>>> Cc: sparclinux@xxxxxxxxxxxxxxx >>>> Cc: linux-um@xxxxxxxxxxxxxxxxxxx >>>> Cc: linux-xtensa@xxxxxxxxxxxxxxxx >>>> Cc: x86@xxxxxxxxxx >>>> Cc: linux-mm@xxxxxxxxx >>>> Cc: linux-kernel@xxxxxxxxxxxxxxx >>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx> >>>> --- >>>> arch/alpha/include/asm/pgtable.h | 1 - >>>> arch/arc/include/asm/pgtable.h | 6 ------ >>>> arch/arm/Kconfig | 1 + >>>> arch/arm64/include/asm/pgtable.h | 2 -- >>>> arch/csky/include/asm/pgtable.h | 1 - >>>> arch/hexagon/include/asm/pgtable.h | 3 --- >>>> arch/ia64/include/asm/pgtable.h | 1 - >>>> arch/m68k/include/asm/pgtable_mm.h | 1 - >>>> arch/microblaze/include/asm/pgtable.h | 2 -- >>>> arch/mips/include/asm/pgtable-32.h | 1 - >>>> arch/mips/include/asm/pgtable-64.h | 1 - >>>> arch/nds32/Kconfig | 1 + >>>> arch/nios2/include/asm/pgtable.h | 2 -- >>>> arch/openrisc/include/asm/pgtable.h | 1 - >>>> arch/parisc/include/asm/pgtable.h | 2 -- >>>> arch/powerpc/include/asm/book3s/pgtable.h | 1 - >>>> arch/powerpc/include/asm/nohash/32/pgtable.h | 1 - >>>> arch/powerpc/include/asm/nohash/64/pgtable.h | 2 -- >>>> arch/riscv/include/asm/pgtable.h | 2 -- >>>> arch/s390/include/asm/pgtable.h | 2 -- >>>> arch/sh/include/asm/pgtable.h | 2 -- >>>> arch/sparc/include/asm/pgtable_32.h | 1 - >>>> arch/sparc/include/asm/pgtable_64.h | 3 --- >>>> arch/um/include/asm/pgtable-2level.h | 1 - >>>> arch/um/include/asm/pgtable-3level.h | 1 - >>>> arch/x86/include/asm/pgtable_types.h | 2 -- >>>> arch/xtensa/include/asm/pgtable.h | 1 - >>>> include/linux/mm.h | 4 ++++ >>>> mm/Kconfig | 4 ++++ >>>> 29 files changed, 10 insertions(+), 43 deletions(-) >>>> >>>> diff --git a/include/linux/mm.h b/include/linux/mm.h >>>> index 8ba434287387..47098ccd715e 100644 >>>> --- a/include/linux/mm.h >>>> +++ b/include/linux/mm.h >>>> @@ -46,6 +46,10 @@ extern int sysctl_page_lock_unfairness; >>>> void init_mm_internals(void); >>>> +#ifndef ARCH_HAS_FIRST_USER_ADDRESS >>> >>> I guess you didn't test it ..... :) >> >> In fact I did :) Though just booted it on arm64 and cross compiled on >> multiple others platforms. I guess for all platforms, ARCH_HAS_FIRST_USER_ADDRESS would have just evaluated to be false hence falling back on the generic definition. So this never complained during build any where or during boot on arm64. >> >>> >>> should be #ifndef CONFIG_ARCH_HAS_FIRST_USER_ADDRESS >> >> Right, meant that instead. >> >>> >>>> +#define FIRST_USER_ADDRESS 0UL >>>> +#endif >>> >>> But why do we need a config option at all for that ? >>> >>> Why not just: >>> >>> #ifndef FIRST_USER_ADDRESS >>> #define FIRST_USER_ADDRESS 0UL >>> #endif >> >> This sounds simpler. But just wondering, would not there be any possibility >> of build problems due to compilation sequence between arch and generic code ? >> > > For sure it has to be addresses carefully, but there are already a lot of stuff like that around pgtables.h > > For instance, pte_offset_kernel() has a generic definition in linux/pgtables.h based on whether it is already defined or not. > > Taking into account that FIRST_USER_ADDRESS is today in the architectures's asm/pgtables.h, I think putting the fallback definition in linux/pgtable.h would do the trick. Agreed, <linux/pgtable.h> includes <asm/pgtable.h> at the beginning and if the arch defines FIRST_USER_ADDRESS, the generic one afterwards would be skipped. The following change builds on multiple platforms. diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index ad086e6d7155..5da96f5df48f 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -7,7 +7,6 @@ config ARM select ARCH_HAS_DEBUG_VIRTUAL if MMU select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE select ARCH_HAS_ELF_RANDOMIZE - select ARCH_HAS_FIRST_USER_ADDRESS select ARCH_HAS_FORTIFY_SOURCE select ARCH_HAS_KEEPINITRD select ARCH_HAS_KCOV diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig index 23ec4fcc0d0f..62313902d75d 100644 --- a/arch/nds32/Kconfig +++ b/arch/nds32/Kconfig @@ -8,7 +8,6 @@ config NDS32 def_bool y select ARCH_32BIT_OFF_T select ARCH_HAS_DMA_PREP_COHERENT - select ARCH_HAS_FIRST_USER_ADDRESS select ARCH_HAS_SYNC_DMA_FOR_CPU select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_WANT_FRAME_POINTERS if FTRACE diff --git a/include/linux/mm.h b/include/linux/mm.h index 47098ccd715e..8ba434287387 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -46,10 +46,6 @@ extern int sysctl_page_lock_unfairness; void init_mm_internals(void); -#ifndef ARCH_HAS_FIRST_USER_ADDRESS -#define FIRST_USER_ADDRESS 0UL -#endif - #ifndef CONFIG_NEED_MULTIPLE_NODES /* Don't use mapnrs, do it properly */ extern unsigned long max_mapnr; diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h index 5e772392a379..f3da6a5cc35a 100644 --- a/include/linux/pgtable.h +++ b/include/linux/pgtable.h @@ -28,6 +28,10 @@ #define USER_PGTABLES_CEILING 0UL #endif +#ifndef FIRST_USER_ADDRESS +#define FIRST_USER_ADDRESS 0UL +#endif + /* * A page table page can be thought of an array like this: pXd_t[PTRS_PER_PxD] * diff --git a/mm/Kconfig b/mm/Kconfig index 373fbe377075..4494501aa403 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -807,9 +807,6 @@ config VMAP_PFN config ARCH_USES_HIGH_VMA_FLAGS bool -config ARCH_HAS_FIRST_USER_ADDRESS - bool - config ARCH_HAS_PKEYS bool -- 2.20.1
