long esi;
long ebp;
long edx;
- long ecx;
long edi;
+ long ecx;
long ebx;
long eax;
long eflags;
#ifdef CONFIG_UST_GDB_INTEGRATION
-//#error "GDB integration not supported for x86-32 yet."
+/* save_registers - saves most of the processor's registers so
+ * they are available to the probe. gdb uses this to give the
+ * value of local variables.
+ *
+ * Saving all registers without losing any of their values is
+ * tricky.
+ *
+ * We cannot pass to the asm stub the address of a registers structure
+ * on the stack, because it will use a register and override its value.
+ *
+ * We don't want to use a stub to push the regs on the stack and then
+ * another stub to copy them to a structure because changing %sp in asm
+ * and then returning to C (even briefly) can have unexpected results.
+ * Also, gcc might modify %sp between the stubs in reaction to the
+ * register needs of the second stub that needs to know where to copy
+ * the register values.
+ *
+ * So the chosen approach is to use another stack, declared in thread-
+ * local storage, to push the registers. They are subsequently copied
+ * to the stack, by C code.
+ */
#define save_registers(regsptr) \
asm volatile ( \
"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" \
- /* rdi is the input to __tls_get_addr, and also a temp var */ \
- "pushl %%edi\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" \
+ /* For TLS access, we have to do function calls. However, \
+ * we must not lose the original value of: \
+ * esp, eflags, eax, ebx, ecx, edx, esi, edi, ebp, cs, ss \
+ * \
+ * Some registers' original values have already been saved: \
+ * esp, eflags, eax, ebx, ecx, edi \
+ * \
+ * In addition, the i386 ABI says the following registers belong\
+ * to the caller function: \
+ * esp, ebp, esi, edi, ebx \
+ * \
+ * The following registers should not be changed by the callee: \
+ * cs, ss \
+ * \
+ * Therefore, the following registers must be explicitly \
+ * preserved: \
+ * edx \
+ */ \
+ "pushl %%edx\n\t" \
+ /* Get GOT address */ \
+ "call __i686.get_pc_thunk.bx\n\t" \
+ "addl $_GLOBAL_OFFSET_TABLE_, %%ebx\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 */ \
/* 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 ecx because we are using it. */ \
+ "pushl %%ecx\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 %%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" \
+ /* edx was pushed for function calls */ \
+ "popl %%edx\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" \
/* -- 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" \
"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 */ \
memcpy(regsptr, (void *)ust_reg_stack_ptr, sizeof(struct registers)); \
ust_reg_stack_ptr = (void *)(((long)ust_reg_stack_ptr) + sizeof(struct registers));
-#define save_ip(channel,name)
-
#else /* CONFIG_UST_GDB_INTEGRATION */
#define save_registers(a)
"pushq %%rbx\n\t" \
/* rdi is the input to __tls_get_addr, and also a temp var */ \
"pushq %%rdi\n\t" \
+ /* For TLS access, we have to do function calls. However, \
+ * we must not lose the original value of: \
+ * rsp, rflags, rax, rbx, rcx, rdx, rsi, rdi, rbp, r8, r9 \
+ * r10, r11, r12, r13, r14, r15, cs, ss \
+ * \
+ * Some registers' original values have already been saved: \
+ * rsp, rflags, rax, rbx, rdi \
+ * \
+ * In addition, the x86-64 ABI says the following registers \
+ * belong to the caller function: \
+ * rbp, rbx, r12, r13, r14, r15 \
+ * \
+ * The following registers should not be changed by the callee: \
+ * cs, ss \
+ * \
+ * Therefore, the following registers must be explicitly \
+ * preserved: \
+ * rcx, rdx, rsi, r8, r9, r10, r11 \
+ */ \
+ "pushq %%rcx\n\t" \
+ "pushq %%rdx\n\t" \
+ "pushq %%rsi\n\t" \
+ "pushq %%r8\n\t" \
+ "pushq %%r9\n\t" \
+ "pushq %%r10\n\t" \
+ "pushq %%r11\n\t" \
/* Start TLS access of private reg stack pointer */ \
".byte 0x66\n\t" \
"leaq ust_reg_stack_ptr@tlsgd(%%rip), %%rdi\n\t" \
/* now the pointer to the private stack is in rax.
must add stack size so the ptr points to the stack bottom. */ \
"1:\n\t" \
+ /* Pop regs that were pushed for function calls */ \
+ "popq %%r11\n\t" \
+ "popq %%r10\n\t" \
+ "popq %%r9\n\t" \
+ "popq %%r8\n\t" \
+ "popq %%rsi\n\t" \
+ "popq %%rdx\n\t" \
+ "popq %%rcx\n\t" \
/* Manually push rsp to private stack */ \
"addq $-8,(%%rax)\n\t" \
"movq 32(%%rsp), %%rdi\n\t" \
projects / ust.git / blobdiff