kasan exchange stacks

asan-poisoning.cc

/**
 This code is useful for moments when the stack might be corrupted.
 On the first asan panic, asan will disable further panics and switch
 to a new stack.
*/

// ktl::atomic<bool> g_asan_panic = false;
// uint8_t kasan_panic_stack[4096];

  if (g_asan_panic.exchange(true)) {
          return;
  }

  uint8_t* newstack = &kasan_panic_stack[4096];

  asm volatile("movq %[Address], %%rdi\n"
               "movq %[Bytes], %%rsi\n"
               "movb %[IsWrite], %%dl\n"
               "movq %[Caller], %%rcx\n"
               "movq %[PoisonedAddr], %%r8\n"
               "leaq %[AsanFail], %%rax\n"
               "movq %[NewStack], %%rsp\n"
               "callq *%%rax\n" :
               /* outputs */ : 
               /* inputs */
               [NewStack] "m" (newstack), 
               [AsanFail] "m" (asan_fail),
               [Address] "m" (address),
               [Bytes] "m" (bytes),
               [IsWrite] "m" (is_write),
               [Caller] "m" (caller),
               [PoisonedAddr] "m" (poisoned_addr) :
               /* clobbers */
               "rsp", "rax", "rdi", "rsi", "rdx", "rcx", "r8");