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db_search_symbol: prevent pollution from bogus symbols
The kernel will never map the first page, so any symbols in that range cannot refer to addresses. Some third-party assembly files define internal constants which appear in their symbol table. Avoiding the lookup for those symbols avoids replacing small offsets with those symbols during disassembly. Reported by: Anton Rang <rang%acm.org> Reviewed by: Anton Rang <rang%acm.org>, markj MFC after: 2 weeks Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D26895
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=367059
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@ -371,8 +371,21 @@ db_search_symbol(db_addr_t val, db_strategy_t strategy, db_expr_t *offp)
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unsigned int diff;
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size_t newdiff;
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int i;
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c_db_sym_t ret = C_DB_SYM_NULL, sym;
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c_db_sym_t ret, sym;
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/*
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* The kernel will never map the first page, so any symbols in that
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* range cannot refer to addresses. Some third-party assembly files
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* define internal constants which appear in their symbol table.
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* Avoiding the lookup for those symbols avoids replacing small offsets
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* with those symbols during disassembly.
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*/
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if (val < PAGE_SIZE) {
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*offp = 0;
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return (C_DB_SYM_NULL);
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}
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ret = C_DB_SYM_NULL;
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newdiff = diff = val;
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for (i = 0; i < db_nsymtab; i++) {
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sym = X_db_search_symbol(&db_symtabs[i], val, strategy, &newdiff);
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