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In a language with free pointers or non-checked array writes (such as in C), the mixing of control flow data which affects the execution of code (the return addresses or the saved frame pointers) and simple program data (parameters or return values) in a call stack is a security risk, and is possibly exploitable through stack buffer overflows ...
In 8086, the main stack register is called "stack pointer" (SP). The stack segment register (SS) is usually used to store information about the memory segment that stores the call stack of currently executed program. SP points to current stack top. By default, the stack grows downward in memory, so newer values are placed at lower memory addresses.
A typical stack, storing local data and call information for nested procedure calls (not necessarily nested procedures). This stack grows downward from its origin. The stack pointer points to the current topmost datum on the stack. A push operation decrements the pointer and copies the data to the stack; a pop operation copies data from the ...
A typical call stack, storing local data and call information for multiple levels of procedure calls. This stack grows downward from its origin. The stack pointer points to the current topmost datum on the stack. A push operation decrements the pointer and copies the data to the stack; a pop operation copies data from the stack and then ...
For leaf-node functions (functions which do not call any other function(s)), a 128-byte space is stored just beneath the stack pointer of the function. The space is called the red zone. This zone will not be overwritten by any signal or interrupt handlers. Compilers can thus use this zone to save local variables.
Default frame pointer. (R8-R13 may also serve as frame pointer and leaf routines may use R1–R3 as frame pointer.) Preserved. Frame Pointer, FP, callee saves: Variables/temporary. Guaranteed. R15: Serves as stack pointer or as a permanent register. Preserved. Stack Pointer, SP, callee saves: Stack pointer. Guaranteed.
SP (Stack pointer): Points to the top of stack in memory. It is automatically updated during PUSH and POP operations. BP (Base Pointer): Points to the top of the call stack. It is primarily used to access function parameters and local variables within the call stack. SI (Source Index): Used as a pointer to the source in string and memory array ...
In a stack machine, the operands used in the instructions are always at a known offset (set in the stack pointer), from a fixed location (the bottom of the stack, which in a hardware design might always be at memory location zero), saving precious in-cache or in-CPU storage from being used to store quite so many memory addresses or index ...