Getting rid of "Cannot access memory at address ..."

Shahab Vahedi shahab.vahedi@gmail.com
Wed Jan 8 13:03:00 GMT 2020


After talking with Andrew, it seemes a possible solution could be using
try/catch to catch the usual suspect (a.k.a. MEMORY_ERROR):

Please let me know what you think of this change?

 diff --git a/gdb/tui/tui-disasm.c b/gdb/tui/tui-disasm.c
 index 98c691f3387..7faaa45f039 100644
 --- a/gdb/tui/tui-disasm.c
 +++ b/gdb/tui/tui-disasm.c
 @@ -226,7 +226,18 @@ tui_disasm_window::set_contents (struct gdbarch *arch,
    /* Get temporary table that will hold all strings (addr & insn).  */
    std::vector<tui_asm_line> asm_lines (max_lines);
    size_t addr_size = 0;
 -  tui_disassemble (gdbarch, asm_lines, pc, 0, max_lines, &addr_size);
 +  try
 +    {
 +      tui_disassemble (gdbarch, asm_lines, pc, 0, max_lines, &addr_size);
 +    }
 +  catch (const gdb_exception &except)
 +    {
 +      /* In cases where max_lines is asking tui_disassemble() to fetch
 +        too much, like when PC goes past the valid address range, a
 +        MEMORY_ERROR is thrown, but it is alright.  */
 +      if (except.error != MEMORY_ERROR)
 +         throw;
 +    }
  
    /* Align instructions to the same column.  */
    insn_pos = (1 + (addr_size / tab_len)) * tab_len;

My only concern is what if we have MEMORY_ERROR exception for reasons other
than disassembling PC addresses that just went beyond the valid range. Do
such reasons exist in this scenario?

--
Shahab



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