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rec: Add endbr64 instructions in the right spots for OpenBSD/amd64 #13430

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merged 1 commit into from
Oct 30, 2023
Merged

rec: Add endbr64 instructions in the right spots for OpenBSD/amd64 #13430

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12 changes: 12 additions & 0 deletions pdns/recursordist/mtasker_fcontext.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -32,6 +32,15 @@ using boost::context::make_fcontext;
using boost::context::detail::make_fcontext;
#endif /* BOOST_VERSION < 106100 */

// __CET__ is set by the compiler if relevant, so far only relevant/tested for amd64 on OpenBSD
#if defined(__amd64__)
#if __CET__ & 0x1
#define CET_ENDBR __asm("endbr64")
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#else
#define CET_ENDBR
#endif
#endif

#ifdef PDNS_USE_VALGRIND
#include <valgrind/valgrind.h>
#endif /* PDNS_USE_VALGRIND */
Expand Down Expand Up @@ -132,6 +141,7 @@ extern "C"
static_cast<fcontext_t>(args->prev_ctx), 0);
#else
transfer_t res = jump_fcontext(t.fctx, 0);
CET_ENDBR;
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/* we got switched back from pdns_swapcontext() */
if (res.data) {
/* if res.data is not a nullptr, it holds a pointer to the context
Expand Down Expand Up @@ -203,6 +213,7 @@ void pdns_swapcontext(pdns_ucontext_t& __restrict octx, pdns_ucontext_t const& _
std::rethrow_exception(origctx->exception);
#else
transfer_t res = jump_fcontext(static_cast<fcontext_t>(ctx.uc_mcontext), &octx.uc_mcontext);
CET_ENDBR;
if (res.data) {
/* if res.data is not a nullptr, it holds a pointer to the context
we just switched from, and we need to fill it to be able to
Expand Down Expand Up @@ -235,6 +246,7 @@ void pdns_makecontext(pdns_ucontext_t& ctx, std::function<void(void)>& start)
#else
transfer_t res = jump_fcontext(static_cast<fcontext_t>(ctx.uc_mcontext),
&args);
CET_ENDBR;
/* back from threadwrapper, updating the context */
ctx.uc_mcontext = res.fctx;
#endif
Expand Down