[PATCH] D105629: [TSan] Add SystemZ support

Tue Jul 13 03:23:03 PDT 2021

uweigand added inline comments.

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Comment at: compiler-rt/lib/tsan/rtl/tsan_platform_posix.cpp:123
+#if defined(__s390x__)
+  ProtectRange(HiAppMemEnd(), 0xfffffffffffff000ull);
+#endif
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iii wrote:
> uweigand wrote:
> > Did you test this on older kernels without 5-level page table support?   I believe the allocation / mprotect may fail on those ...
> No, not really. Would it make sense to probe here? E.g. first try 0xfffffffffffff000, then 0x20000000000000. Or is there a way to query user_addr_max() / TASK_SIZE_MAX / TASK_SIZE?
I don't know of any way to query this.  You can simply do the allocation in stages (first to the top of the three-pagetable range, then four, then five), and ignore failures.   As an unfortunate side effect this will force the kernel to allocate five levels of page tables even when unnecessary, but I don't think there's anything we can do about that.

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Comment at: compiler-rt/lib/tsan/rtl/tsan_rtl_s390x.S:22
+  CFI_REL_OFFSET(%r2, R2_REL_OFFSET)
+  CFI_REL_OFFSET(%r3, R3_REL_OFFSET)
+  stmg %r14, %r15, R14_REL_OFFSET(%r15)
----------------
iii wrote:
> uweigand wrote:
> > Do we need CFI for r2/r3 ?  Those are call-clobbered any cannot be unwound normally anyway ...
> I'm not quite sure, but glibc does this (e.g. in sysdeps/s390/s390-64/dl-trampoline.h), so I figured I'll do this here as well just in case.
Huh.   Well I guess it doesn't hurt either way.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105629/new/

https://reviews.llvm.org/D105629