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by krackers
229 days ago
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The stack does grow down though no matter what, in the sense that the pushing decrements the stack pointer. You can represent this as "up" in your diagram, but I don't think this makes it any easier conceptually because by analogy to a simple push/pop on an array, you'd naively expect higher addresses to contain more recent stack contents. The core of the issue is that the direction stack growth differs from "usual" memory access patterns which usually allocate from lower to higher addresses (consider array access, or how strings are laid out in memory. And little-endian systems are the majority) But if we're going with visualization options I prefer to visualize it horizontally, with lower addresses on left. This has a natural correspondence with how you access an array or lay out strings in memory. |
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Do not confuse this with push and pop on an abstract stack data structure. That is not the same as the process stack. On a real process stack, newer data is stored at LOWER addresses. In fact, every push decrements the stack pointer (the address is decreased).
If you want an example, think about how a string is placed and accessed on the stack. First, the stack pointer is decremented to reserve space (so in my diagram this “moves up” visually). Then the string can be read byte by byte by incrementing an index from the lower address toward the higher address. This is exactly like reading a book: left to right, top to bottom. If you flip memory upside down, everything becomes unnatural to understand: you would have to read the string from the bottom to the top.
Try decompiling a program with Ghidra. Open the disassembly view and look at the addresses on the left. Lower addresses are shown at the top. Higher addresses are shown at the bottom. In my diagram this matches perfectly. Everything is consistent and you never have to mentally flip the memory layout.
Years of practice led me to this, not just theory.