Fix Stack Unwind for ARM/Linux

Make context information compatible with libunwind-arm.

In Linux/ARM, seh-unwind.cpp has been updating unw_cursor_t
to point another stack by updating the cursor's register
entries. However, that does not work in libunwind-arm in
Linux, which breaks PAL_VirtualUnwind() functions.
Getting the stack information from the cursor had
a compatibility issue as well.

This patch make both "context->cursor" and "cursor->context"
methods compatible with ARM/Linux.

Fix #3312

Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>

1 files changed, 25 insertions, 13 deletions

diff --git a/src/pal/src/exception/seh-unwind.cpp b/src/pal/src/exception/seh-unwind.cpp
index 5d3b353494..ea17cce29e 100644
--- a/src/pal/src/exception/seh-unwind.cpp
+++ b/src/pal/src/exception/seh-unwind.cpp
@@ -97,17 +97,29 @@ static void WinContextToUnwindCursor(CONTEXT *winContext, unw_cursor_t *cursor)
     unw_set_reg(cursor, UNW_X86_64_R14, winContext->R14);
     unw_set_reg(cursor, UNW_X86_64_R15, winContext->R15);
 #elif defined(_ARM_)
-    unw_set_reg(cursor, UNW_ARM_R13, winContext->Sp);
-    unw_set_reg(cursor, UNW_ARM_R14, winContext->Lr);
-    unw_set_reg(cursor, UNW_ARM_R15, winContext->Pc);
-    unw_set_reg(cursor, UNW_ARM_R4, winContext->R4);
-    unw_set_reg(cursor, UNW_ARM_R5, winContext->R5);
-    unw_set_reg(cursor, UNW_ARM_R6, winContext->R6);
-    unw_set_reg(cursor, UNW_ARM_R7, winContext->R7);
-    unw_set_reg(cursor, UNW_ARM_R8, winContext->R8);
-    unw_set_reg(cursor, UNW_ARM_R9, winContext->R9);
-    unw_set_reg(cursor, UNW_ARM_R10, winContext->R10);
-    unw_set_reg(cursor, UNW_ARM_R11, winContext->R11);
+    // Assuming that unw_set_reg() on cursor will point the cursor to the
+    // supposed stack frame is dangerous for libunwind-arm in Linux.
+    // It is because libunwind's unw_cursor_t has other data structure
+    // initialized by unw_init_local(), which are not updated by
+    // unw_set_reg().
+    unw_context_t context;
+    context.regs[0] = 0;
+    context.regs[1] = 0;
+    context.regs[2] = 0;
+    context.regs[3] = 0;
+    context.regs[4] = winContext->R4;
+    context.regs[5] = winContext->R5;
+    context.regs[6] = winContext->R6;
+    context.regs[7] = winContext->R7;
+    context.regs[8] = winContext->R8;
+    context.regs[9] = winContext->R9;
+    context.regs[10] = winContext->R10;
+    context.regs[11] = winContext->R11;
+    context.regs[12] = 0;
+    context.regs[13] = winContext->Sp;
+    context.regs[14] = winContext->Lr;
+    context.regs[15] = winContext->Pc;
+    unw_init_local(cursor, &context);
 #endif
 }
 #endif
@@ -124,9 +136,9 @@ static void UnwindContextToWinContext(unw_cursor_t *cursor, CONTEXT *winContext)
     unw_get_reg(cursor, UNW_X86_64_R14, (unw_word_t *) &winContext->R14);
     unw_get_reg(cursor, UNW_X86_64_R15, (unw_word_t *) &winContext->R15);
 #elif defined(_ARM_)
-    unw_get_reg(cursor, UNW_ARM_R13, (unw_word_t *) &winContext->Sp);
+    unw_get_reg(cursor, UNW_REG_SP, (unw_word_t *) &winContext->Sp);
+    unw_get_reg(cursor, UNW_REG_IP, (unw_word_t *) &winContext->Pc);
     unw_get_reg(cursor, UNW_ARM_R14, (unw_word_t *) &winContext->Lr);
-    unw_get_reg(cursor, UNW_ARM_R15, (unw_word_t *) &winContext->Pc);
     unw_get_reg(cursor, UNW_ARM_R4, (unw_word_t *) &winContext->R4);
     unw_get_reg(cursor, UNW_ARM_R5, (unw_word_t *) &winContext->R5);
     unw_get_reg(cursor, UNW_ARM_R6, (unw_word_t *) &winContext->R6);