[ARM/FDPIC v6 11/24] [ARM] FDPIC: Add support to unwind FDPIC signal frame

2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
	Mickaël Guêné <mickael.guene@st.com>

	libgcc/
	* unwind-arm-common.inc (ARM_SET_R7_RT_SIGRETURN)
	(THUMB2_SET_R7_RT_SIGRETURN, FDPIC_LDR_R12_WITH_FUNCDESC)
	(FDPIC_LDR_R9_WITH_GOT, FDPIC_LDR_PC_WITH_RESTORER)
	(FDPIC_FUNCDESC_OFFSET, ARM_NEW_RT_SIGFRAME_UCONTEXT)
	(ARM_UCONTEXT_SIGCONTEXT, ARM_SIGCONTEXT_R0, FDPIC_T2_LDR_R12_WITH_FUNCDESC)
	(FDPIC_T2_LDR_R9_WITH_GOT, FDPIC_T2_LDR_PC_WITH_RESTORER): New.
	(__gnu_personality_sigframe_fdpic): New.
	(get_eit_entry): Add FDPIC signal frame support.

Co-Authored-By: Mickaël Guêné <mickael.guene@st.com>
From-SVN: r275573

diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index 8f29b5ed6080041269b3ae32f059f1b23720c723..d6d73e9660b81271bb37ad5dc5dc29fd2ab068fc 100644 (file)
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,16 @@
+2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
+       Mickaël Guêné <mickael.guene@st.com>
+
+       libgcc/
+       * unwind-arm-common.inc (ARM_SET_R7_RT_SIGRETURN)
+       (THUMB2_SET_R7_RT_SIGRETURN, FDPIC_LDR_R12_WITH_FUNCDESC)
+       (FDPIC_LDR_R9_WITH_GOT, FDPIC_LDR_PC_WITH_RESTORER)
+       (FDPIC_FUNCDESC_OFFSET, ARM_NEW_RT_SIGFRAME_UCONTEXT)
+       (ARM_UCONTEXT_SIGCONTEXT, ARM_SIGCONTEXT_R0, FDPIC_T2_LDR_R12_WITH_FUNCDESC)
+       (FDPIC_T2_LDR_R9_WITH_GOT, FDPIC_T2_LDR_PC_WITH_RESTORER): New.
+       (__gnu_personality_sigframe_fdpic): New.
+       (get_eit_entry): Add FDPIC signal frame support.
+
 2019-09-10  Christophe Lyon  <christophe.lyon@st.com>
        Mickaël Guêné <mickael.guene@st.com>
 

diff --git a/libgcc/unwind-arm-common.inc b/libgcc/unwind-arm-common.inc
index 0bacc11ef1a75ad6d0ba35cb296527c648c38b17..c9a82b79bc85743fdcaa1e7855c9f2114bb3d1a6 100644 (file)
--- a/libgcc/unwind-arm-common.inc
+++ b/libgcc/unwind-arm-common.inc
@@ -30,6 +30,26 @@
 #include <sys/sdt.h>
 #endif
 
+#if __FDPIC__
+/* Load r7 with rt_sigreturn value.  */
+#define ARM_SET_R7_RT_SIGRETURN                0xe3a070ad      /* mov   r7, #0xad */
+#define THUMB2_SET_R7_RT_SIGRETURN     0x07adf04f      /* mov.w r7, #0xad */
+
+/* FDPIC jump to restorer sequence.  */
+#define FDPIC_LDR_R12_WITH_FUNCDESC    0xe59fc004      /* ldr   r12, [pc, #4] */
+#define FDPIC_LDR_R9_WITH_GOT          0xe59c9004      /* ldr   r9, [r12, #4] */
+#define FDPIC_LDR_PC_WITH_RESTORER     0xe59cf000      /* ldr   pc, [r12] */
+#define FDPIC_T2_LDR_R12_WITH_FUNCDESC  0xc008f8df     /* ldr.w r12, [pc, #8] */
+#define FDPIC_T2_LDR_R9_WITH_GOT       0x9004f8dc      /* ldr.w r9, [r12, #4] */
+#define FDPIC_T2_LDR_PC_WITH_RESTORER   0xf000f8dc     /* ldr.w pc, [r12] */
+#define FDPIC_FUNCDESC_OFFSET          12
+
+/* Signal frame offsets.  */
+#define ARM_NEW_RT_SIGFRAME_UCONTEXT   0x80
+#define ARM_UCONTEXT_SIGCONTEXT                0x14
+#define ARM_SIGCONTEXT_R0              0xc
+#endif
+
 /* We add a prototype for abort here to avoid creating a dependency on
    target headers.  */
 extern void abort (void);
@@ -199,6 +219,45 @@ search_EIT_table (const __EIT_entry * table, int nrec, _uw return_address)
     }
 }
 
+#if __FDPIC__
+/* VFP is not restored, but this is sufficient to allow unwinding.  */
+static _Unwind_Reason_Code
+__gnu_personality_sigframe_fdpic (_Unwind_State state,
+                                 _Unwind_Control_Block *ucbp,
+                                 _Unwind_Context *context)
+{
+    unsigned int sp;
+    unsigned int pc;
+    unsigned int funcdesc;
+    unsigned int handler;
+    unsigned int first_handler_instruction;
+    int i;
+
+    _Unwind_VRS_Get (context, _UVRSC_CORE, R_SP, _UVRSD_UINT32, &sp);
+    _Unwind_VRS_Get (context, _UVRSC_CORE, R_PC, _UVRSD_UINT32, &pc);
+
+    funcdesc = *(unsigned int *)((pc & ~1) + FDPIC_FUNCDESC_OFFSET);
+    handler = *(unsigned int *)(funcdesc);
+    first_handler_instruction = *(unsigned int *)(handler & ~1);
+
+    /* Adjust SP to point to the start of registers according to
+       signal type.  */
+    if (first_handler_instruction == ARM_SET_R7_RT_SIGRETURN
+       || first_handler_instruction == THUMB2_SET_R7_RT_SIGRETURN)
+       sp += ARM_NEW_RT_SIGFRAME_UCONTEXT
+         + ARM_UCONTEXT_SIGCONTEXT
+         + ARM_SIGCONTEXT_R0;
+    else
+       sp += ARM_UCONTEXT_SIGCONTEXT
+         + ARM_SIGCONTEXT_R0;
+    /* Restore regs saved on stack by the kernel.  */
+    for (i = 0; i < 16; i++)
+       _Unwind_VRS_Set (context, _UVRSC_CORE, i, _UVRSD_UINT32, sp + 4 * i);
+
+    return _URC_CONTINUE_UNWIND;
+}
+#endif
+
 /* Find the exception index table eintry for the given address.
    Fill in the relevant fields of the UCB.
    Returns _URC_FAILURE if an error occurred, _URC_OK on success.  */
@@ -222,6 +281,27 @@ get_eit_entry (_Unwind_Control_Block *ucbp, _uw return_address)
                                                            &nrec);
       if (!eitp)
        {
+#if __FDPIC__
+         /* If we are unwinding a signal handler then perhaps we have
+            reached a trampoline.  Try to detect jump to restorer
+            sequence.  */
+         _uw *pc = (_uw *)((return_address+2) & ~1);
+         if ((pc[0] == FDPIC_LDR_R12_WITH_FUNCDESC
+              && pc[1] == FDPIC_LDR_R9_WITH_GOT
+              && pc[2] == FDPIC_LDR_PC_WITH_RESTORER)
+             || (pc[0] == FDPIC_T2_LDR_R12_WITH_FUNCDESC
+                 && pc[1] == FDPIC_T2_LDR_R9_WITH_GOT
+                 && pc[2] == FDPIC_T2_LDR_PC_WITH_RESTORER))
+           {
+             struct funcdesc_t *funcdesc
+               = (struct funcdesc_t *) &__gnu_personality_sigframe_fdpic;
+
+             UCB_PR_ADDR (ucbp) = funcdesc->ptr;
+             UCB_PR_GOT (ucbp) = funcdesc->got;
+
+             return _URC_OK;
+           }
+#endif
          UCB_PR_ADDR (ucbp) = 0;
          return _URC_FAILURE;
        }
@@ -236,6 +316,27 @@ get_eit_entry (_Unwind_Control_Block *ucbp, _uw return_address)
 
   if (!eitp)
     {
+#if __FDPIC__
+      /* If we are unwinding a signal handler then perhaps we have
+        reached a trampoline.  Try to detect jump to restorer
+        sequence.  */
+      _uw *pc = (_uw *)((return_address+2) & ~1);
+      if ((pc[0] == FDPIC_LDR_R12_WITH_FUNCDESC
+          && pc[1] == FDPIC_LDR_R9_WITH_GOT
+          && pc[2] == FDPIC_LDR_PC_WITH_RESTORER)
+         || (pc[0] == FDPIC_T2_LDR_R12_WITH_FUNCDESC
+             && pc[1] == FDPIC_T2_LDR_R9_WITH_GOT
+             && pc[2] == FDPIC_T2_LDR_PC_WITH_RESTORER))
+       {
+         struct funcdesc_t *funcdesc
+           = (struct funcdesc_t *) &__gnu_personality_sigframe_fdpic;
+
+         UCB_PR_ADDR (ucbp) = funcdesc->ptr;
+         UCB_PR_GOT (ucbp) = funcdesc->got;
+
+         return _URC_OK;
+       }
+#endif
       UCB_PR_ADDR (ucbp) = 0;
       return _URC_FAILURE;
     }
@@ -244,6 +345,27 @@ get_eit_entry (_Unwind_Control_Block *ucbp, _uw return_address)
   /* Can this frame be unwound at all?  */
   if (eitp->content == EXIDX_CANTUNWIND)
     {
+#if __FDPIC__
+      /* If we are unwinding a signal handler then perhaps we have
+        reached a trampoline.  Try to detect jump to restorer
+        sequence.  */
+      _uw *pc = (_uw *)((return_address+2) & ~1);
+      if ((pc[0] == FDPIC_LDR_R12_WITH_FUNCDESC
+          && pc[1] == FDPIC_LDR_R9_WITH_GOT
+          && pc[2] == FDPIC_LDR_PC_WITH_RESTORER)
+         || (pc[0] == FDPIC_T2_LDR_R12_WITH_FUNCDESC
+             && pc[1] == FDPIC_T2_LDR_R9_WITH_GOT
+             && pc[2] == FDPIC_T2_LDR_PC_WITH_RESTORER))
+       {
+         struct funcdesc_t *funcdesc
+           = (struct funcdesc_t *) &__gnu_personality_sigframe_fdpic;
+
+         UCB_PR_ADDR (ucbp) = funcdesc->ptr;
+         UCB_PR_GOT (ucbp) = funcdesc->got;
+
+         return _URC_OK;
+       }
+#endif
       UCB_PR_ADDR (ucbp) = 0;
       return _URC_END_OF_STACK;
     }