Kees Cook <keesc...@chromium.org> wrote: > On Mon, Jun 4, 2018 at 4:21 AM, Nadav Amit <na...@vmware.com> wrote: >> GCC considers the number of statements in inlined assembly blocks, >> according to new-lines and semicolons, as an indication to the cost of >> the block in time and space. This data is distorted by the kernel code, >> which puts information in alternative sections. As a result, the >> compiler may perform incorrect inlining and branch optimizations. >> >> The solution is to set an assembly macro and call it from the inlined >> assembly block. As a result GCC considers the inline assembly block as >> a single instruction. >> >> This patch allows to inline functions such as __get_seccomp_filter(). >> Interestingly, this allows more aggressive inlining while reducing the >> kernel size. >> >> text data bss dec hex filename >> 18140970 10225412 2957312 31323694 1ddf62e ./vmlinux before >> 18140140 10225284 2957312 31322736 1ddf270 ./vmlinux after (-958) >> >> Static text symbols: >> Before: 40302 >> After: 40286 (-16) >> >> Functions such as kref_get(), free_user(), fuse_file_get() now get >> inlined. >> >> Cc: Thomas Gleixner <t...@linutronix.de> >> Cc: Ingo Molnar <mi...@redhat.com> >> Cc: "H. Peter Anvin" <h...@zytor.com> >> Cc: x...@kernel.org >> Cc: Kees Cook <keesc...@chromium.org> >> Cc: Jan Beulich <jbeul...@suse.com> >> Cc: Josh Poimboeuf <jpoim...@redhat.com> >> >> Signed-off-by: Nadav Amit <na...@vmware.com> >> --- >> arch/x86/include/asm/refcount.h | 73 ++++++++++++++++++++------------- >> arch/x86/kernel/macros.S | 1 + >> 2 files changed, 45 insertions(+), 29 deletions(-) >> >> diff --git a/arch/x86/include/asm/refcount.h >> b/arch/x86/include/asm/refcount.h >> index 4cf11d88d3b3..53462f32b58e 100644 >> --- a/arch/x86/include/asm/refcount.h >> +++ b/arch/x86/include/asm/refcount.h >> @@ -4,6 +4,9 @@ >> * x86-specific implementation of refcount_t. Based on PAX_REFCOUNT from >> * PaX/grsecurity. >> */ >> + >> +#ifndef __ASSEMBLY__ > > Can you swap the order here, so that the asm macros are visible first > in the file? > > #ifdef __ASSEMBLY__ > ...macros > #else > ....C > #endif
Done. I also noticed that I forgot in one instance (REFCOUNT_CHECK_LT_ZERO) to explicitly mark the parameter name (“counter=\counter”), so I’ll fix it as well in the next version.
