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edb4d95ddf
If an allocation failed within LLVM it is not safe to call back into LLVM as LLVM is not generally safe against exceptions / stack-unwinding. Thus errors while in LLVM code are promoted to FATAL. However llvm_shutdown() did call back into LLVM even in such cases, while llvm_release_context() was careful not to do so. We cannot generally skip shutting down LLVM, as that can break profiling. But it's OK to do so if there was an error from within LLVM. Reported-By: Jelte Fennema <Jelte.Fennema@microsoft.com> Author: Andres Freund <andres@anarazel.de> Author: Justin Pryzby <pryzby@telsasoft.com> Discussion: https://postgr.es/m/AM5PR83MB0178C52CCA0A8DEA0207DC14F7FF9@AM5PR83MB0178.EURPRD83.prod.outlook.com Backpatch: 11-, where jit was introduced
152 lines
3.8 KiB
C++
152 lines
3.8 KiB
C++
/*-------------------------------------------------------------------------
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*
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* llvmjit_error.cpp
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* LLVM error related handling that requires interfacing with C++
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*
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* Unfortunately neither (re)setting the C++ new handler, nor the LLVM OOM
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* handler are exposed to C. Therefore this file wraps the necessary code.
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*
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* Copyright (c) 2016-2021, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* src/backend/jit/llvm/llvmjit_error.cpp
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*
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*-------------------------------------------------------------------------
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*/
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extern "C"
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{
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#include "postgres.h"
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}
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#include <llvm/Support/ErrorHandling.h>
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#include "jit/llvmjit.h"
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static int fatal_new_handler_depth = 0;
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static std::new_handler old_new_handler = NULL;
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static void fatal_system_new_handler(void);
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#if LLVM_VERSION_MAJOR > 4
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static void fatal_llvm_new_handler(void *user_data, const std::string& reason, bool gen_crash_diag);
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#endif
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static void fatal_llvm_error_handler(void *user_data, const std::string& reason, bool gen_crash_diag);
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/*
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* Enter a section in which C++ and LLVM errors are treated as FATAL errors.
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*
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* This is necessary for LLVM as LLVM's error handling for such cases
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* (exit()ing, throwing std::bad_alloc() if compiled with exceptions, abort())
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* isn't compatible with postgres error handling. Thus in sections where LLVM
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* code, not LLVM generated functions!, is executing, standard new, LLVM OOM
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* and LLVM fatal errors (some OOM errors masquerade as those) are redirected
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* to our own error handlers.
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*
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* These error handlers use FATAL, because there's no reliable way from within
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* LLVM to throw an error that's guaranteed not to corrupt LLVM's state.
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*
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* To avoid disturbing extensions using C++ and/or LLVM, these handlers are
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* unset when not executing LLVM code. There is no need to call
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* llvm_leave_fatal_on_oom() when ERRORing out, error recovery resets the
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* handlers in that case.
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*/
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void
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llvm_enter_fatal_on_oom(void)
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{
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if (fatal_new_handler_depth == 0)
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{
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old_new_handler = std::set_new_handler(fatal_system_new_handler);
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#if LLVM_VERSION_MAJOR > 4
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llvm::install_bad_alloc_error_handler(fatal_llvm_new_handler);
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#endif
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llvm::install_fatal_error_handler(fatal_llvm_error_handler);
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}
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fatal_new_handler_depth++;
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}
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/*
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* Leave fatal error section started with llvm_enter_fatal_on_oom().
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*/
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void
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llvm_leave_fatal_on_oom(void)
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{
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fatal_new_handler_depth--;
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if (fatal_new_handler_depth == 0)
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{
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std::set_new_handler(old_new_handler);
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#if LLVM_VERSION_MAJOR > 4
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llvm::remove_bad_alloc_error_handler();
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#endif
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llvm::remove_fatal_error_handler();
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}
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}
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/*
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* Are we currently in an fatal-on-oom section? Useful to skip cleanup in case
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* of errors.
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*/
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bool
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llvm_in_fatal_on_oom(void)
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{
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return fatal_new_handler_depth > 0;
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}
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/*
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* Reset fatal error handling. This should only be called in error recovery
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* loops like PostgresMain()'s.
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*/
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void
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llvm_reset_after_error(void)
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{
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if (fatal_new_handler_depth != 0)
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{
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std::set_new_handler(old_new_handler);
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#if LLVM_VERSION_MAJOR > 4
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llvm::remove_bad_alloc_error_handler();
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#endif
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llvm::remove_fatal_error_handler();
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}
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fatal_new_handler_depth = 0;
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}
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void
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llvm_assert_in_fatal_section(void)
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{
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Assert(fatal_new_handler_depth > 0);
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}
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static void
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fatal_system_new_handler(void)
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{
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ereport(FATAL,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("out of memory"),
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errdetail("while in LLVM")));
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}
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#if LLVM_VERSION_MAJOR > 4
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static void
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fatal_llvm_new_handler(void *user_data,
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const std::string& reason,
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bool gen_crash_diag)
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{
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ereport(FATAL,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("out of memory"),
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errdetail("While in LLVM: %s", reason.c_str())));
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}
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#endif
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static void
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fatal_llvm_error_handler(void *user_data,
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const std::string& reason,
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bool gen_crash_diag)
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{
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ereport(FATAL,
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(errcode(ERRCODE_OUT_OF_MEMORY),
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errmsg("fatal llvm error: %s",
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reason.c_str())));
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}
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