x86, x86-64: restore the stack frame correctly when unwinding

In addition to space reserved for locals, unwinding has to account for
callee-saved registers and other values saved on the stack. Both x86 and
x86-64 were affected, the former since it adopted a few stack layout
changes (standard prologs/epilogs and canaries), while the latter seems
to have been affected for a long time.

Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

6 files changed, 32 insertions, 2 deletions

diff --git a/arch/x86/include/arch/stack-frame.h b/arch/x86/include/arch/stack-frame.h
index d19e58e4..aa932fe4 100644
--- a/arch/x86/include/arch/stack-frame.h
+++ b/arch/x86/include/arch/stack-frame.h
@@ -43,5 +43,6 @@ unsigned long slot_offset(struct stack_slot *slot);
 unsigned long slot_offset_64(struct stack_slot *slot);
 unsigned long frame_locals_size(struct stack_frame *frame);
 unsigned long cu_frame_locals_offset(struct compilation_unit *cu);
+unsigned long cu_frame_total_offset(struct compilation_unit *cu);
 
 #endif
diff --git a/arch/x86/stack-frame.c b/arch/x86/stack-frame.c
index 236c2960..1aa884bf 100644
--- a/arch/x86/stack-frame.c
+++ b/arch/x86/stack-frame.c
@@ -32,6 +32,7 @@
 #include "jit/compiler.h"
 #include "jit/args.h"
 #include "jit/text.h"
+#include "jit/debug.h"
 
 #include "vm/stack-trace.h"
 #include "vm/method.h"
@@ -58,6 +59,19 @@
 
 #define ARGS_START_OFFSET offsetof(struct jit_stack_frame, args)
 
+#ifdef CONFIG_X86_32
+static unsigned long cu_frame_misc_size(struct compilation_unit *cu)
+{
+	return (opt_debug_stack ? sizeof(unsigned long) : 0);	/* canary */
+}
+#else
+static unsigned long cu_frame_misc_size(struct compilation_unit *cu)
+{
+	return sizeof(unsigned long) +				/* *this */
+	       (opt_debug_stack ? sizeof(unsigned long) : 0);	/* canary */
+}
+#endif
+
 static unsigned long __index_to_offset(unsigned long index)
 {
 	return index * sizeof(unsigned long);
@@ -120,6 +134,17 @@ unsigned long cu_frame_locals_offset(struct compilation_unit *cu)
 }
 
 /*
+ * Returns offset to subtract from the
+ * stack pointer to reserve space for the entire stack frame.
+ */
+unsigned long cu_frame_total_offset(struct compilation_unit *cu)
+{
+	return cu_frame_locals_offset(cu) +
+	       sizeof(unsigned long) * NR_CALLEE_SAVE_REGS +
+	       cu_frame_misc_size(cu);
+}
+
+/*
  * Checks whether given native function was called from jit trampoline
  * code. It checks whether return address points after a relative call
  * to jit_magic_trampoline, which is typical for trampolines.
diff --git a/arch/x86/unwind_32.S b/arch/x86/unwind_32.S
index f9056ac2..faf829dd 100644
--- a/arch/x86/unwind_32.S
+++ b/arch/x86/unwind_32.S
@@ -28,7 +28,7 @@ unwind:
 	 */
 	push	%edx
 	push	%ecx
-	call	cu_frame_locals_offset
+	call	cu_frame_total_offset
 	pop	%ecx
 	pop	%edx
 
diff --git a/arch/x86/unwind_64.S b/arch/x86/unwind_64.S
index 464c8443..d61754e0 100644
--- a/arch/x86/unwind_64.S
+++ b/arch/x86/unwind_64.S
@@ -26,7 +26,7 @@ unwind:
 
 	movq 	%rax, %rdi
 	movq	0x08(%rsp), %rsi
-	call	cu_frame_locals_offset
+	call	cu_frame_total_offset
 
 	pop	%rdi
 
diff --git a/test/unit/arch-x86/Makefile b/test/unit/arch-x86/Makefile
index 1be7feb5..3e9bd66a 100644
--- a/test/unit/arch-x86/Makefile
+++ b/test/unit/arch-x86/Makefile
@@ -12,6 +12,7 @@ TOPLEVEL_OBJS	+= lib/buffer.o
 TOPLEVEL_OBJS	+= lib/hash-map.o
 TOPLEVEL_OBJS	+= lib/string.o
 TOPLEVEL_OBJS	+= lib/symbol.o
+TOPLEVEL_OBJS	+= test/unit/jit/emit-stub.o
 TOPLEVEL_OBJS	+= test/unit/libharness/libharness.o
 TOPLEVEL_OBJS	+= test/unit/vm/stack-trace-stub.o
 TOPLEVEL_OBJS	+= test/unit/vm/trace-stub.o
diff --git a/test/unit/jit/emit-stub.c b/test/unit/jit/emit-stub.c
new file mode 100644
index 00000000..a97cf547
--- /dev/null
+++ b/test/unit/jit/emit-stub.c
@@ -0,0 +1,3 @@
+#include "jit/debug.h"
+
+bool opt_debug_stack;