x86-intel-align32.c

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// -*-Mode: C++;-*- // technically C99

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#include <string.h>
#include "x86-unwind-interval-fixup.h"
#include "x86-unwind-interval.h"

static char intel_align32_signature[] = { 
 0x53,                          // push   %rbx
 0x48, 0x89, 0xe3,              // mov    %rsp,%rbx
 0x48, 0x83, 0xe4, 0xe0,        // and    $0xffffffffffffffe0,%rsp
 0x55,                          // push   %rbp
 0x55,                          // push   %rbp
 0x48, 0x8b, 0x6b, 0x08,        // mov    0x8(%rbx),%rbp
 0x48, 0x89, 0x6c, 0x24, 0x08,  // mov    %rbp,0x8(%rsp)
 0x48, 0x89, 0xe5,              // mov    %rsp,%rbp
};


int 
x86_adjust_intel_align32_intervals(char *ins, int len, btuwi_status_t *stat)
{
  int siglen = sizeof(intel_align32_signature);

  if (len > siglen && strncmp((char *)intel_align32_signature, ins, siglen) == 0) {
    // signature matched 
    unwind_interval *ui = (unwind_interval *) stat->first;

    // this won't fix all of the intervals, but it will fix the ones 
    // that we care about.
    //
    // The method is as follows:
    // Ignore (do not correct) intervals before 1st std frame
    // For 1st STD_FRAME, compute the corrections for this interval and subsequent intervals
    // For this interval and subsequent interval, apply the corrected offsets
    //

    for(; UWI_RECIPE(ui)->ra_status != RA_STD_FRAME; ui = UWI_NEXT(ui));

    // this is only correct for 64-bit code
    for(; ui; ui = UWI_NEXT(ui)) { 
      x86recipe_t *xr = UWI_RECIPE(ui);
      if (xr->ra_status == RA_SP_RELATIVE) continue;
      if (((xr->ra_status == RA_STD_FRAME) || 
           (xr->ra_status == RA_BP_FRAME)) && 
          (xr->reg.bp_status == BP_SAVED)) {  
         xr->ra_status = RA_BP_FRAME;
         xr->reg.bp_ra_pos = 8;
         xr->reg.bp_bp_pos = 0;
      }
    }

    return 1;
  } 
  return 0;
}