Add some sanity to save_registers on x86-32

Fixes a crash

diff --git a/include/ust/processor.h b/include/ust/processor.h
index 987f75e6cee329b2baba95fb623bc9c8efe302a7..305284b4ea3f5dd5fd8818d506bb0a3cab57599d 100644 (file)
--- a/include/ust/processor.h
+++ b/include/ust/processor.h
@@ -15,8 +15,8 @@ struct registers {
        long esi;
        long ebp;
        long edx;
-       long ecx;
        long edi;
+       long ecx;
        long ebx;
        long eax;
        long eflags;
@@ -35,46 +35,66 @@ struct registers {
             "pushfl\n\t" \
              /* eax will hold the ptr to the private stack bottom */ \
             "pushl %%eax\n\t" \
-            /* ebx will be used to temporarily hold the stack bottom addr */ \
+            /* ebx is used for TLS access */ \
             "pushl %%ebx\n\t" \
+            /* ecx will be used to temporarily hold the stack bottom addr */ \
+            "pushl %%ecx\n\t" \
             /* rdi is the input to __tls_get_addr, and also a temp var */ \
             "pushl %%edi\n\t" \
+            /* Get GOT address */ \
+            "call __i686.get_pc_thunk.bx\n\t" \
+            "addl $_GLOBAL_OFFSET_TABLE_, %%ebx\n\t" \
+            /* Save registers before call (not using ecx yet but we must preserve \
+               the original value of edx. */ \
+            "pushl %%edx\n\t" \
             /* Start TLS access of private reg stack pointer */ \
             "leal ust_reg_stack_ptr@tlsgd(,%%ebx,1),%%eax\n\t" \
             "call ___tls_get_addr@plt\n\t" \
             /* --- End TLS access */ \
+            "popl %%edx\n\t" \
             /* check if ust_reg_stack_ptr has been initialized */ \
-            "movl (%%eax),%%ebx\n\t" \
-            "testl %%ebx,%%ebx\n\t" \
+            "movl (%%eax),%%ecx\n\t" \
+            "testl %%ecx,%%ecx\n\t" \
             "jne 1f\n\t" \
-            "movl %%eax,%%ebx\n\t" \
+            "movl %%eax,%%ecx\n\t" \
+            /* Save registers before call (using ecx and we must preserve \
+               the original value of edx. */ \
+            "pushl %%ecx\n\t" \
+            "pushl %%edx\n\t" \
             /* Start TLS access of private reg stack */ \
             "leal ust_reg_stack@tlsgd(,%%ebx,1),%%eax\n\t" \
             "call ___tls_get_addr@plt\n\t" \
             /* --- End TLS access */ \
+            "popl %%edx\n\t" \
+            "popl %%ecx\n\t" \
             "addl $500,%%eax\n\t" \
-            "movl %%eax,(%%ebx)\n\t" \
-            "movl %%ebx,%%eax\n\t" \
+            "movl %%eax,(%%ecx)\n\t" \
+            "movl %%ecx,%%eax\n\t" \
             /* now the pointer to the private stack is in eax. \
                must add stack size so the ptr points to the stack bottom. */ \
        "1:\n\t" \
             /* Manually push esp to private stack */ \
             "addl $-4,(%%eax)\n\t" \
-            "movl 16(%%esp), %%edi\n\t" \
+            "movl 20(%%esp), %%edi\n\t" \
             "movl (%%eax), %%ebx\n\t" \
             "movl %%edi, (%%ebx)\n\t" \
             /* Manually push eflags to private stack */ \
             "addl $-4,(%%eax)\n\t" \
-            "movl 12(%%esp), %%edi\n\t" \
+            "movl 16(%%esp), %%edi\n\t" \
             "movl (%%eax), %%ebx\n\t" \
             "movl %%edi, (%%ebx)\n\t" \
             /* Manually push eax to private stack */ \
             "addl $-4,(%%eax)\n\t" \
-            "movl 8(%%esp), %%edi\n\t" \
+            "movl 12(%%esp), %%edi\n\t" \
             "movl (%%eax), %%ebx\n\t" \
             "movl %%edi, (%%ebx)\n\t" \
             /* Manually push ebx to private stack */ \
             "addl $-4,(%%eax)\n\t" \
+            "movl 8(%%esp), %%edi\n\t" \
+            "movl (%%eax), %%ebx\n\t" \
+            "movl %%edi, (%%ebx)\n\t" \
+            /* Manually push ecx to private stack */ \
+            "addl $-4,(%%eax)\n\t" \
             "movl 4(%%esp), %%edi\n\t" \
             "movl (%%eax), %%ebx\n\t" \
             "movl %%edi, (%%ebx)\n\t" \
@@ -87,12 +107,10 @@ struct registers {
             /* -- esp already pushed -- */ \
             /* -- eax already pushed -- */ \
             /* -- ebx already pushed -- */ \
+            /* -- ecx already pushed -- */ \
             /* -- edi already pushed -- */ \
             "addl $-4,(%%eax)\n\t" \
             "movl (%%eax), %%ebx\n\t" \
-            "movl %%ecx,(%%ebx)\n\t" \
-            "addl $-4,(%%eax)\n\t" \
-            "movl (%%eax), %%ebx\n\t" \
             "movl %%edx,(%%ebx)\n\t" \
             "addl $-4,(%%eax)\n\t" \
             "movl (%%eax), %%ebx\n\t" \
@@ -110,6 +128,7 @@ struct registers {
             "movw %%ss, (%%ebx)\n\t" \
             /* restore original values of regs that were used internally */ \
             "popl %%edi\n\t" \
+            "popl %%ecx\n\t" \
             "popl %%ebx\n\t" \
             "popl %%eax\n\t" \
             /* cancel push of rsp */ \