Messages in this thread | | | From | Dominik Brodowski <> | Subject | [RFC PATCH v3 0/6] x86/entry/64: interrupt entry size reduction | Date | Tue, 20 Feb 2018 22:01:07 +0100 |
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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-usSg@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
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