remove the last set_fs() in common code, and remove it for x86 and powerpc

Christoph Hellwig
2020-08-17T07:32:42Z

Hi all,

this series removes the last set_fs() used to force a kernel address
space for the uaccess code in the kernel read/write/splice code, and then
stops implementing the address space overrides entirely for x86 and
powerpc.

The file system part has been posted a few times, and the read/write side
has been pretty much unchanced. For splice this series drops the
conversion of the seq_file and sysctl code to the iter ops, and thus loses
the splice support for them. The reasons for that is that it caused a lot
of churn for not much use - splice for these small files really isn't much
of a win, even if existing userspace uses it. All callers I found do the
proper fallback, but if this turns out to be an issue the conversion can
be resurrected.

Besides x86 and powerpc I plan to eventually convert all other
architectures, although this will be a slow process, starting with the
easier ones once the infrastructure is merged. The process to convert
architectures is roughtly:

- ensure there is no set_fs(KERNEL_DS) left in arch specific code
- implement __get_kernel_nofault and __put_kernel_nofault
- remove the arch specific address limitation functionality

Diffstat:
arch/Kconfig | 3
arch/alpha/Kconfig | 1
arch/arc/Kconfig | 1
arch/arm/Kconfig | 1
arch/arm64/Kconfig | 1
arch/c6x/Kconfig | 1
arch/csky/Kconfig | 1
arch/h8300/Kconfig | 1
arch/hexagon/Kconfig | 1
arch/ia64/Kconfig | 1
arch/m68k/Kconfig | 1
arch/microblaze/Kconfig | 1
arch/mips/Kconfig | 1
arch/nds32/Kconfig | 1
arch/nios2/Kconfig | 1
arch/openrisc/Kconfig | 1
arch/parisc/Kconfig | 1
arch/powerpc/include/asm/processor.h | 7 -
arch/powerpc/include/asm/thread_info.h | 5 -
arch/powerpc/include/asm/uaccess.h | 78 ++++++++-----------
arch/powerpc/kernel/signal.c | 3
arch/powerpc/lib/sstep.c | 6 -
arch/riscv/Kconfig | 1
arch/s390/Kconfig | 1
arch/sh/Kconfig | 1
arch/sparc/Kconfig | 1
arch/um/Kconfig | 1
arch/x86/ia32/ia32_aout.c | 1
arch/x86/include/asm/page_32_types.h | 11 ++
arch/x86/include/asm/page_64_types.h | 38 +++++++++
arch/x86/include/asm/processor.h | 60 ---------------
arch/x86/include/asm/thread_info.h | 2
arch/x86/include/asm/uaccess.h | 26 ------
arch/x86/kernel/asm-offsets.c | 3
arch/x86/lib/getuser.S | 28 ++++---
arch/x86/lib/putuser.S | 21 +++--
arch/xtensa/Kconfig | 1
drivers/char/mem.c | 16 ----
drivers/misc/lkdtm/bugs.c | 2
drivers/misc/lkdtm/core.c | 4 +
drivers/misc/lkdtm/usercopy.c | 2
fs/read_write.c | 69 ++++++++++-------
fs/splice.c | 130 +++------------------------------
include/linux/fs.h | 2
include/linux/uaccess.h | 18 ++++
lib/test_bitmap.c | 10 ++
46 files changed, 235 insertions(+), 332 deletions(-)