Here is another re-spin of the interrupt entry size reduction patchset,
which applies on top of tip/pti and tries to implement what Linus
suggested a few days ago.[*]
Patch 1/5 provides the most significant cuttings (-3k) and gets us below
the text size of entry_64.o (by about 2k) compared to before I started
meddling with it. This patch is the most evolved of the set, yet saw the
helper function being renamed since v2.
The other five patches still need more discussion on whether each
additional step and the code complexity it adds is really worth it. And
stringent review, of course.
Overall, these patches provide for a sizeable cutting of up to 4.5k compared
to tip/pti:
text data bss dec hex filename
19500 0 0 19500 4c2c entry_64.o-orig (before 2e3f0098bc45)
21088 0 0 21088 5260 entry_64.o-pti (as of ced5d0bf603f)
18006 0 0 18006 4656 entry_64.o (patch 1/6)
16623 0 0 16623 40ef entry_64.o (patch 6/6)
Changes for v3:
- patch 1:
- rename interrupt_helper to interrupt_entry (suggested by Josh
Poimboeuf)
- do not add cld to interrupt_entry yet
- patch 2 (follow-up changes only)
- patch 3:
- move cld from interrupt macro to interrupt_entry (suggestion
by Linus Torvalds to make this more explicit)
- do not add cld to switch_to_thread_stack wrapper function, but
keep cld where it is entry_INT80_compat.
- patch 4: (follow-up changes only)
- patch 5 (NEW):
- move ASM_CLAC to interrupt helper (suggested by Brian Gerst)
- patch 6 (was patch 5/5 in v2):
- update commentary (suggested by Josh Poimboeuf)
- remove unused UNWIND hint from entry_64_compat.S (suggested by
Josh Poimboeuf)
Changes for v2:
- patch 1 (unchanged)
- patch 2:
- use leaq 8() instead of mov+addq in ENTER_IRQ_STACK (suggested
by Brian Gerst)
- add UNWIND_HINT_REGS indirect=1 after call to interrupt_helper;
update size information accordingly
- patch 3:
- add cld to switch_to_thread_stack wrapper function
- improve commit message
- update size information
- patch 4:
- add UNWIND_HINT_REGS indirect=1 to the now-removed interrupt
macro
- patch 5 (NEW):
- open-code the DO_SWITCH_TO_THREAD_STACK macro (suggested by
Brian Gerst)
- improve (?) UNWIND hints
[*]
http://lkml.kernel.org/r/CA+55aFwLTF3EtaQ4OpDv2UM41J=EU7gfemv=evq+uqi31-u...@mail.gmail.com
Dominik Brodowski (6):
x86/entry/64: move PUSH_AND_CLEAR_REGS from interrupt macro to helper
function
x86/entry/64: move ENTER_IRQ_STACK from interrupt macro to
interrupt_entry
x86/entry/64: move switch_to_thread_stack to interrupt_entry
x86/entry/64: remove interrupt macro
x86/entry/64: move ASM_CLAC to interrupt_entry
x86/entry/64: open-code switch_to_thread_stack
arch/x86/entry/entry_64.S | 132 ++++++++++++++++++++++++---------------
arch/x86/entry/entry_64_compat.S | 17 ++++-
2 files changed, 98 insertions(+), 51 deletions(-)
--
2.16.2
