Gdb Cannot access memory at address

Question

I want to use breakpoint in the UPtest function to stop at 0x000000000040124c.

run 111 222 333 I need to display the 32 records at the top of the stack.

x / 32wx $ esp, but show Cannot access memory at address 0xffffffffffffe0a0.

I want to find the return address of the main program, how do I change it to display it?Like the picture below.

Answer 1

The problem you're having is that the $esp register is 32-bit, but addresses on your target are 64-bit. When you do x/32wx $esp GDB is reading the $rsp register, which has the value 0x7fffffffffffe0a0 and masking this to 32-bits, so 0xffffe0a0 , then it is sign extending this to 64-bit, giving 0xffffffffffffe0a0 .

Try x/32wx $rsp and you should have more luck.