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eh_elf: Implement step_cursor
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parent
7f70295713
commit
e0efd00acd
3 changed files with 85 additions and 9 deletions
13
src/eh_elf/context_struct.h
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13
src/eh_elf/context_struct.h
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@ -0,0 +1,13 @@
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#include <stdint.h>
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typedef struct {
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uintptr_t rip, rsp, rbp;
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} unwind_context_t;
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typedef uintptr_t (*deref_func_t)(uintptr_t);
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typedef unwind_context_t (*_fde_func_t)(unwind_context_t, uintptr_t);
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typedef unwind_context_t (*_fde_func_with_deref_t)(
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unwind_context_t,
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uintptr_t,
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deref_func_t);
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@ -13,6 +13,10 @@
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************************************************/
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#include "eh_elf.h"
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#include "context_struct.h"
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#include "libunwind.h"
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#include "memory_map.h"
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#include "remote.h"
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int eh_elf_init_local() {
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return mmap_init_local();
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@ -26,7 +30,70 @@ void eh_elf_clear() {
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mmap_clear();
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}
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int eh_elf_step_cursor(struct cursor *cursor) {
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// TODO implement
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return 0;
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static struct {
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unw_addr_space_t addr_space;
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unw_accessors_t *accessors;
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void* arg;
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} _fetch_state;
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static uintptr_t fetchw_here(uintptr_t addr) {
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uintptr_t out;
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fetchw(_fetch_state.addr_space,
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_fetch_state.accessors,
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&addr,
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&out,
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_fetch_state.arg);
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return out;
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}
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int eh_elf_step_cursor(struct cursor *cursor) {
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uintptr_t ip = cursor->dwarf.ip;
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// Retrieve memory map entry
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mmap_entry_t* mmap_entry = mmap_get_entry(ip);
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if(mmap_entry == NULL)
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return -1;
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// Retrieve a pointer to the eh_elf function
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_fde_func_with_deref_t fde_func =
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(_fde_func_t) (dlsym(mmap_entry->eh_elf, "_eh_elf"));
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if(fde_func == NULL)
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return -2;
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// Setup an eh_elf context
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unwind_context_t eh_elf_context;
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eh_elf_context.rip = ip;
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eh_elf_context.rsp = cursor->dwarf.loc[UNW_TDEP_SP].val;
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eh_elf_context.rbp = cursor->dwarf.loc[UNW_TDEP_BP].val;
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// Set _fetch_state before passing fetchw_here
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_fetch_state.addr_space = cursor->dwarf.as;
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_fetch_state.accessors = &cursor->dwarf.as->acc;
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// Call fde_func
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eh_elf_context = fde_func(
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eh_elf_context,
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ip - mmap_entry->offset,
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fetchw_here);
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// Check for the end of the call chain
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if(eh_elf_context.rbp == 0 || eh_elf_context.rip + 1 == 0)
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return 0;
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// Push back the data into libunwind's structures
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for (int i = 0; i < DWARF_NUM_PRESERVED_REGS; ++i)
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cursor->dwarf.loc[i] = DWARF_NULL_LOC;
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cursor->dwarf.loc[UNW_TDEP_BP].val = eh_elf_context.rbp;
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cursor->dwarf.loc[UNW_TDEP_SP].val = eh_elf_context.rsp;
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cursor->dwarf.loc[UNW_TDEP_IP].val = eh_elf_context.rip;
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cursor->dwarf.use_prev_instr = 1;
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cursor->frame_info.frame_type = UNW_X86_64_FRAME_GUESSED;
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cursor->frame_info.cfa_reg_rsp = 0;
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cursor->frame_info.cfa_reg_offset = 16;
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cursor->frame_info.rbp_cfa_offset = -16;
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cursor->dwarf.cfa += 16;
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return 1;
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}
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@ -17,11 +17,6 @@
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#include <sys/types.h>
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#include "libunwind_i.h"
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/// Store the necessary data for a single eh_elf
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typedef struct {
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// TODO
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} eh_elf_handle_t;
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/** Initialize everything for local memory analysis
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* @return 0 on success, or a negative value upon failure
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**/
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@ -37,6 +32,7 @@ void eh_elf_clear();
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/** Step the cursor using eh_elf mechanisms.
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*
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* Return 0 if everything went fine, otherwise, return a negative value.
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* @return a positive value upon success, 0 if the frame before this unwinding
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* was the last one, or a negative value upon failure.
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**/
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int eh_elf_step_cursor(struct cursor *cursor);
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