At Linux Plumbers, Andy Lutomirski approached me to tell me that the
syscall_get_arguments() implementation in x86 was horrible and gcc
certainly gets it wrong. He said that since the tracepoints only pass
in 0 and 6 for i and n repectively, it should be optimized for that case.
Inspecting the kernel, I discovered that all users pass in 0 for i and
only one file passing in something other than 6 for the number of arguments.
That code happens to be my own code used for the special syscall tracing.
That can easily be converted to just using 0 and 6 as well, and only copying
what is needed. Which is probably the faster path anyway for that case.
I haven't run the numbers (I can do that when I get some time), but since
pretty much all use cases use 0 and 6 and that would allow these functions
not to need strange logic to handle odd cases, I think this is still a win.
I haven't looked at removing those same parameters from syscall_set_arguments()
yet.
Thoughts?
-- Steve
Steven Rostedt (3):
ptrace: Remove maxargs from task_current_syscall()
tracing/syscalls: Pass in hardcoded '6' into syscall_get_arguments()
syscalls: Remove start and number from syscall_get_arguments() args
----
arch/arc/include/asm/syscall.h | 7 ++--
arch/arm/include/asm/syscall.h | 23 ++---------
arch/arm64/include/asm/syscall.h | 22 ++---------
arch/blackfin/include/asm/syscall.h | 22 +++++++----
arch/c6x/include/asm/syscall.h | 41 ++++----------------
arch/frv/include/asm/syscall.h | 26 +++----------
arch/h8300/include/asm/syscall.h | 34 ++++-------------
arch/hexagon/include/asm/syscall.h | 4 +-
arch/ia64/include/asm/syscall.h | 5 +--
arch/metag/include/asm/syscall.h | 4 +-
arch/microblaze/include/asm/syscall.h | 4 +-
arch/mips/include/asm/syscall.h | 3 +-
arch/mn10300/include/asm/syscall.h | 32 +++-------------
arch/nios2/include/asm/syscall.h | 42 ++++----------------
arch/openrisc/include/asm/syscall.h | 6 +--
arch/parisc/include/asm/syscall.h | 30 ++++-----------
arch/powerpc/include/asm/syscall.h | 8 ++--
arch/s390/include/asm/syscall.h | 11 +++---
arch/sh/include/asm/syscall_32.h | 26 +++----------
arch/sh/include/asm/syscall_64.h | 4 +-
arch/sparc/include/asm/syscall.h | 4 +-
arch/tile/include/asm/syscall.h | 4 +-
arch/um/include/asm/syscall-generic.h | 39 +++----------------
arch/x86/include/asm/syscall.h | 72 ++++++++---------------------------
fs/proc/base.c | 2 +-
include/asm-generic/syscall.h | 11 ++----
include/linux/ptrace.h | 4 +-
include/trace/events/syscalls.h | 2 +-
kernel/seccomp.c | 2 +-
kernel/trace/trace_syscalls.c | 10 +++--
lib/syscall.c | 22 ++++-------
31 files changed, 139 insertions(+), 387 deletions(-)
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