lkml.org 
[lkml]   [2022]   [Jun]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH V3 0/7] x86/entry: Convert error_entry() to C code
    On Mon, Jun 6, 2022 at 10:44 PM Lai Jiangshan <jiangshanlai@gmail.com> wrote:
    >
    > From: Lai Jiangshan <jiangshan.ljs@antgroup.com>
    >
    > Add some C equivalent functions of the ASM macros and implement the whole
    > error_entry() as C code.
    >
    > The patches are picked and re-made from the huge patchset
    > https://lore.kernel.org/lkml/20211126101209.8613-1-jiangshanlai@gmail.com/
    > which converts a large chunk of ASM code to C code.
    >
    > The C version generally has better readability and easier to be
    > updated/improved.
    >
    > This smaller patchset converts error_entry() only.
    > The equivalent ASM macros are not removed because they are still used by
    > the IST exceptions.
    >
    > No functional change intended and comments are also copied.
    >
    > The complier generates very similar code for the C code and the original
    > ASM code except minor differences.
    >
    > The complier uses tail-call-optimization for calling sync_regs(). It
    > uses "JMP sync_regs" while the ASM code uses "CALL+RET".
    >
    > The compiler generates "AND $0xe7,%ah" (3 bytes) for the code
    > "cr3 = user_cr3 & ~PTI_USER_PGTABLE_AND_PCID_MASK" while the ASM code in
    > SWITCH_TO_KERNEL_CR3() results "AND $0xffffffffffffe7ff,%rax" (6 bytes).
    >
    > The compiler generates lengthier code for "cr3 |= X86_CR3_PCID_NOFLUSH"
    > because it uses "MOVABS+OR" (13 bytes) rather than a single
    > "BTS" (5 bytes).
    >
    > ALTERNATIVE and static_cpu_has() are also different which depends on
    > what alternative instructions for ALTERNATIVE are.
    >
    > [V2]: https://lore.kernel.org/lkml/20220516131739.521817-1-jiangshanlai@gmail.com/
    > [V1]: https://lore.kernel.org/lkml/20220511072747.3960-1-jiangshanlai@gmail.com/
    >
    > Changed from V2:
    > Fix conflict in arch/x86/include/asm/proto.h in patch7
    >
    > Changed from V1:
    > remove unneeded cleanup in patch2
    >
    > Changed from the old huge patchset:
    > squash some patches
    >

    Hello, ALL,

    Ping

    Thanks,
    Lai

    \
     
     \ /
      Last update: 2022-06-17 02:23    [W:3.099 / U:0.860 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site