116 lines
3.4 KiB
Diff
116 lines
3.4 KiB
Diff
From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
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From: Tom de Vries <tdevries@suse.de>
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Date: Fri, 21 May 2021 15:09:14 +0200
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Subject: gdb-rhbz-2130624-assert_in_jit_event_handler.patch
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;; Backport "[gdb/breakpoint] Fix assert in jit_event_handler"
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;; (Tom de Vries, RHBZ2130624)
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Consider a minimal test-case test.c:
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...
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int main (void) { return 0; }
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...
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which we can compile into llvm byte code using clang:
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...
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$ clang -g -S -emit-llvm --target=x86_64-unknown-unknown-elf test.c
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...
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and then run using lli, which uses the llvm jit:
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...
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$ lli test.ll
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...
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If we run this under gdb, we run into an assert:
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...
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$ gdb -q -batch -ex run --args /usr/bin/lli test.ll
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Dwarf Error: Cannot not find DIE at 0x18a936e7 \
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[from module libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug]
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[Thread debugging using libthread_db enabled]
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Using host libthread_db library "/lib64/libthread_db.so.1".
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src/gdb/jit.c:1178: internal-error: \
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void jit_event_handler(gdbarch*, objfile*): \
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Assertion `jiter->jiter_data != nullptr' failed.
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...
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This is caused by the following.
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When running jit_breakpoint_re_set_internal, we first handle
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libLLVM.so.10.debug, and set a jit breakpoint.
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Next we handle libLLVM.so.10:
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...
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(gdb) p the_objfile.original_name
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$42 = 0x2494170 "libLLVM.so.10"
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...
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but the minimal symbols we find are from libLLVM.so.10.debug:
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(gdb) p reg_symbol.objfile.original_name
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$43 = 0x38e7c50 "libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug"
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(gdb) p desc_symbol.objfile.original_name
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$44 = 0x38e7c50 "libLLVM.so.10-10.0.1-lp152.30.4.x86_64.debug"
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...
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and consequently, the objf_data is the one from libLLVM.so.10.debug:
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jiter_objfile_data *objf_data
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= get_jiter_objfile_data (reg_symbol.objfile);
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...
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and so we hit this:
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if (objf_data->cached_code_address == addr)
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continue;
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...
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and no second jit breakpoint is inserted.
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Subsequently, the jit breakpoint is triggered and handled, but when finding
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the symbol for the breakpoint address we get:
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...
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(gdb) p jit_bp_sym.objfile.original_name
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$52 = 0x2494170 "libLLVM.so.10"
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...
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The assert 'jiter->jiter_data != nullptr' triggers because it checks
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libLLVM.so.10 while the one with jiter_data setup is libLLVM.so.10.debug.
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This fixes the assert:
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...
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jiter_objfile_data *objf_data
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- = get_jiter_objfile_data (reg_symbol.objfile);
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- = get_jiter_objfile_data (the_objfile);
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...
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but consequently we'll have two jit breakpoints, so we also make sure we don't
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set a jit breakpoint on separate debug objects like libLLVM.so.10.debug.
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Tested on x86_64-linux.
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gdb/ChangeLog:
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2021-05-21 Tom de Vries <tdevries@suse.de>
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PR breakpoint/27889
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* jit.c (jit_breakpoint_re_set_internal): Skip separate debug
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objects. Call get_jiter_objfile_data with the_objfile.
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diff --git a/gdb/jit.c b/gdb/jit.c
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--- a/gdb/jit.c
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+++ b/gdb/jit.c
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@@ -893,6 +893,10 @@ jit_breakpoint_re_set_internal (struct gdbarch *gdbarch, program_space *pspace)
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{
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for (objfile *the_objfile : pspace->objfiles ())
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{
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+ /* Skip separate debug objects. */
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+ if (the_objfile->separate_debug_objfile_backlink != nullptr)
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+ continue;
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+
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if (the_objfile->skip_jit_symbol_lookup)
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continue;
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@@ -919,7 +923,7 @@ jit_breakpoint_re_set_internal (struct gdbarch *gdbarch, program_space *pspace)
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}
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jiter_objfile_data *objf_data
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- = get_jiter_objfile_data (reg_symbol.objfile);
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+ = get_jiter_objfile_data (the_objfile);
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objf_data->register_code = reg_symbol.minsym;
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objf_data->descriptor = desc_symbol.minsym;
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