On Fri, 20 May 2022 16:05:44 +0200 Janis Schoetterl-Glausch <scgl@xxxxxxxxxxxxx> wrote: > gcc 12 warns if a memory operand to inline asm points to memory in the > first 4k bytes. However, in our case, these operands are fine, either > because we actually want to use that memory, or expect and handle the > resulting exception. > > v1 -> v2 > * replace mechanism, don't use pragmas, instead use an extern symbol so > gcc cannot conclude that the pointer is <4k this is a hack, but it's a nice hack it gets rid of the compiler warning, and it also simplifies the existing code. > > This new extern symbol refers to the lowcore. As a result, code > generation for lowcore accesses becomes worse. > > Alternatives: > * Don't use extern symbol for lowcore, just for problematic pointers > * Hide value from gcc via inline asm > * Disable the warning globally > * Use memory clobber instead of memory output > Use address in register input instead of memory input > (may require WRITE_ONCE) > * Don't use gcc 12.0, with newer versions --param=min-pagesize=0 might > avoid the problem > > Janis Schoetterl-Glausch (2): > s390x: Introduce symbol for lowcore and use it > s390x: Fix gcc 12 warning about array bounds > > lib/s390x/asm/arch_def.h | 2 ++ > lib/s390x/asm/facility.h | 4 +-- > lib/s390x/asm/mem.h | 4 +++ > lib/s390x/css.h | 2 -- > lib/s390x/css_lib.c | 12 ++++---- > lib/s390x/fault.c | 10 +++---- > lib/s390x/interrupt.c | 61 +++++++++++++++++++------------------- > lib/s390x/mmu.c | 3 +- > s390x/flat.lds | 1 + > s390x/snippets/c/flat.lds | 1 + > s390x/css.c | 4 +-- > s390x/diag288.c | 4 +-- > s390x/edat.c | 5 ++-- > s390x/emulator.c | 15 +++++----- > s390x/mvpg.c | 7 ++--- > s390x/sclp.c | 3 +- > s390x/skey.c | 2 +- > s390x/skrf.c | 11 +++---- > s390x/smp.c | 23 +++++++------- > s390x/snippets/c/spec_ex.c | 5 ++-- > 20 files changed, 83 insertions(+), 96 deletions(-) > > > base-commit: 8719e8326101c1be8256617caf5835b57e819339
