[PATCH v3 0/7] x86: Rewrite switch_to()

From	Brian Gerst <brgerst@gmail.com>
Newsgroups	linux.kernel
Subject	[PATCH v3 0/7] x86: Rewrite switch_to()
Date	2016-08-13 18:40 +0200
Message-ID	<s5K8x-3J2-9@gated-at.bofh.it> (permalink)
Organization	linux.* mail to news gateway

Show all headers | View raw

This patch set simplifies the switch_to() code, by moving the stack switch
code out of line into an asm stub before calling __switch_to().  This ends
up being more readable, and using the C calling convention instead of
clobbering all registers improves code generation.  It also allows newly
forked processes to construct a special stack frame to seamlessly flow
to ret_from_fork, instead of using a test and branch, or an unbalanced
call/ret.

Changes from v2:
- Updated comments around kernel threads being uncommon for fork, etc.
- Removed STACK_FRAME_NON_STANDARD annotation from __schedule() per Josh Poimboeuf
- A few minor cleanups added

Changes from v1:
- Added struct inactive_task_frame
- Added comments about kernel threads returning to userspace
- Cleaned up some incorrect uses of thread.sp
- Rearranged inactive stack frame so that BP (frame pointer) is in the natural position right below the return address.  This should take care of unwinding issues Josh raised.

Brian Gerst (7):
  x86-32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs()
  x86-64, kgdb: clear GDB_PS on 64-bit
  x86: Add struct inactive_task_frame
  x86: Rewrite switch_to() code
  x86: Pass kernel thread parameters in fork_frame
  x86: Fix thread_saved_pc()
  Revert "sched: Mark __schedule() stack frame as non-standard"

 arch/x86/entry/entry_32.S          |  68 +++++++++++++-----
 arch/x86/entry/entry_64.S          |  78 ++++++++++++++------
 arch/x86/include/asm/processor.h   |  13 +---
 arch/x86/include/asm/stacktrace.h  |   4 +-
 arch/x86/include/asm/switch_to.h   | 144 ++++++++-----------------------------
 arch/x86/include/asm/thread_info.h |   2 -
 arch/x86/kernel/asm-offsets.c      |   6 ++
 arch/x86/kernel/asm-offsets_32.c   |   5 ++
 arch/x86/kernel/asm-offsets_64.c   |   5 ++
 arch/x86/kernel/kgdb.c             |   8 +--
 arch/x86/kernel/process.c          |  14 +++-
 arch/x86/kernel/process_32.c       |  31 +++-----
 arch/x86/kernel/process_64.c       |  21 +++---
 arch/x86/kernel/smpboot.c          |   1 -
 kernel/sched/core.c                |   1 -
 15 files changed, 190 insertions(+), 211 deletions(-)

-- 
2.5.5

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

[PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
  [PATCH v3 1/7] x86-32, kgdb: Don't use thread.ip in sleeping_thread_to_gdb_regs() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
    [tip:x86/asm] sched/x86/32, kgdb: Don't use thread.ip in  sleeping_thread_to_gdb_regs() tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
  [PATCH v3 7/7] Revert "sched: Mark __schedule() stack frame as non-standard" Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
    [tip:x86/asm] sched: Remove __schedule() non-standard frame  annotation tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
  [PATCH v3 2/7] x86-64, kgdb: clear GDB_PS on 64-bit Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
    [tip:x86/asm] sched/x86/64, kgdb: Clear GDB_PS on 64-bit tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:50 +0200
  [PATCH v3 3/7] x86: Add struct inactive_task_frame Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:40 +0200
    [tip:x86/asm] sched/x86: Add 'struct inactive_task_frame' to better  document the sleeping task stack frame tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
  [PATCH v3 4/7] x86: Rewrite switch_to() code Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:50 +0200
    [tip:x86/asm] sched/x86: Rewrite the switch_to() code tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
  [PATCH v3 6/7] x86: Fix thread_saved_pc() Brian Gerst <brgerst@gmail.com> - 2016-08-13 18:50 +0200
    [tip:x86/asm] sched/x86: Fix thread_saved_pc() tip-bot for Brian Gerst <tipbot@zytor.com> - 2016-08-24 15:20 +0200
  Re: [PATCH v3 0/7] x86: Rewrite switch_to() Linus Torvalds <torvalds@linux-foundation.org> - 2016-08-13 19:20 +0200
    Re: [PATCH v3 0/7] x86: Rewrite switch_to() Ingo Molnar <mingo@kernel.org> - 2016-08-14 10:30 +0200
      Re: [PATCH v3 0/7] x86: Rewrite switch_to() Andy Lutomirski <luto@amacapital.net> - 2016-08-14 13:20 +0200
        Re: [PATCH v3 0/7] x86: Rewrite switch_to() Herbert Xu <herbert@gondor.apana.org.au> - 2016-08-17 07:20 +0200
      Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-14 16:20 +0200
        Re: [PATCH v3 0/7] x86: Rewrite switch_to() Ingo Molnar <mingo@kernel.org> - 2016-08-15 07:20 +0200
          Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-15 13:50 +0200
          Re: [PATCH v3 0/7] x86: Rewrite switch_to() Andy Lutomirski <luto@amacapital.net> - 2016-08-17 23:30 +0200
    Re: [PATCH v3 0/7] x86: Rewrite switch_to() Brian Gerst <brgerst@gmail.com> - 2016-08-14 12:30 +0200
  Re: [PATCH v3 0/7] x86: Rewrite switch_to() Josh Poimboeuf <jpoimboe@redhat.com> - 2016-08-17 23:30 +0200

csiph-web