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_ADDRESSI guess you didn't test it ..... :)In fact I did :) Though just booted it on arm64 and cross compiled on multiple others platforms.should be #ifndef CONFIG_ARCH_HAS_FIRST_USER_ADDRESSRight, meant that instead.+#define FIRST_USER_ADDRESS 0UL +#endifBut why do we need a config option at all for that ? Why not just: #ifndef FIRST_USER_ADDRESS #define FIRST_USER_ADDRESS 0UL #endifThis 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.
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