Here is a 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 unchanged to v1 and seems to be the most trivial of this patchset (famous last words), but still requires stringent review before being applied. The other four 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 4.1k 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 1/5) 16882 0 0 16882 41f2 entry_64.o (patch 5/5) [*] http://lkml.kernel.org/r/CA+55aFwLTF3EtaQ4OpDv2UM41J=EU7gfemv=evq+uqi31-u...@mail.gmail.com Changes since v1: - 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 Dominik Brodowski (5): 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 helper function x86/entry/64: move switch_to_thread_stack to interrupt helper function x86/entry/64: remove interrupt macro x86/entry/64: open-code switch_to_thread_stack arch/x86/entry/entry_64.S | 105 +++++++++++++++++++++++---------------- arch/x86/entry/entry_64_compat.S | 19 ++++++- 2 files changed, 81 insertions(+), 43 deletions(-) -- 2.16.1
