cregit-Linux how code gets into the kernel

Release 4.9 arch/x86/kernel/unwind_frame.c

Directory: arch/x86/kernel
#include <linux/sched.h>
#include <asm/ptrace.h>
#include <asm/bitops.h>
#include <asm/stacktrace.h>
#include <asm/unwind.h>


#define FRAME_HEADER_SIZE (sizeof(long) * 2)


unsigned long unwind_get_return_address(struct unwind_state *state) { unsigned long addr; unsigned long *addr_p = unwind_get_return_address_ptr(state); if (unwind_done(state)) return 0; addr = ftrace_graph_ret_addr(state->task, &state->graph_idx, *addr_p, addr_p); return __kernel_text_address(addr) ? addr : 0; }

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EXPORT_SYMBOL_GPL(unwind_get_return_address);
static bool update_stack_state(struct unwind_state *state, void *addr, size_t len) { struct stack_info *info = &state->stack_info; /* * If addr isn't on the current stack, switch to the next one. * * We may have to traverse multiple stacks to deal with the possibility * that 'info->next_sp' could point to an empty stack and 'addr' could * be on a subsequent stack. */ while (!on_stack(info, addr, len)) if (get_stack_info(info->next_sp, state->task, info, &state->stack_mask)) return false; return true; }

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bool unwind_next_frame(struct unwind_state *state) { unsigned long *next_bp; if (unwind_done(state)) return false; next_bp = (unsigned long *)*state->bp; /* make sure the next frame's data is accessible */ if (!update_stack_state(state, next_bp, FRAME_HEADER_SIZE)) return false; /* move to the next frame */ state->bp = next_bp; return true; }

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EXPORT_SYMBOL_GPL(unwind_next_frame);
void __unwind_start(struct unwind_state *state, struct task_struct *task, struct pt_regs *regs, unsigned long *first_frame) { memset(state, 0, sizeof(*state)); state->task = task; /* don't even attempt to start from user mode regs */ if (regs && user_mode(regs)) { state->stack_info.type = STACK_TYPE_UNKNOWN; return; } /* set up the starting stack frame */ state->bp = get_frame_pointer(task, regs); /* initialize stack info and make sure the frame data is accessible */ get_stack_info(state->bp, state->task, &state->stack_info, &state->stack_mask); update_stack_state(state, state->bp, FRAME_HEADER_SIZE); /* * The caller can provide the address of the first frame directly * (first_frame) or indirectly (regs->sp) to indicate which stack frame * to start unwinding at. Skip ahead until we reach it. */ while (!unwind_done(state) && (!on_stack(&state->stack_info, first_frame, sizeof(long)) || state->bp < first_frame)) unwind_next_frame(state); }

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EXPORT_SYMBOL_GPL(__unwind_start);

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Directory: arch/x86/kernel