[compiler-rt] [asan] Intercept __makecontext_v2 on Solaris/SPARC (PR #81588)

[Rainer Orth via llvm-commits]

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@@ -352,8 +352,16 @@ static void ClearShadowMemoryForContextStack(uptr stack, uptr ssize) {
   PoisonShadow(bottom, ssize, 0);
 }
 
+// Since Solaris 10/SPARC, ucp->uc_stack.ss_sp refers to the stack base address
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rorth wrote:

LLVM only supports Solaris 11.4 for quite some time, it doesn't even build on 11.3 let alone 9.

Right: old executables could only be exposed to `libclang_rt.asan.so` via `LD_PRELOAD`, and I have a hard time believing anyone is still running Solaris 9 these days and suddendly develops a need for asan.  These days, you could only access the old `makecontext` if you declare it yourself: when including `<ucontext.h>`, you only get the v2 symbol on sparc.

https://github.com/llvm/llvm-project/pull/81588