1 files changed, 110 insertions, 60 deletions

diff --git a/gas/gen-sframe.c b/gas/gen-sframe.c
index 5c8c7eb..2d1c196 100644
--- a/gas/gen-sframe.c
+++ b/gas/gen-sframe.c
@@ -30,18 +30,6 @@
 # define sizeof_member(type, member)	(sizeof (((type *)0)->member))
 #endif
 
-/* Whether frame row entries track RA.
-
-   A target may not need return address tracking for stack tracing.  If it
-   does need the same, SFRAME_CFA_RA_REG must be defined with the return
-   address register number.  */
-
-#if defined (sframe_ra_tracking_p) && defined (SFRAME_CFA_RA_REG)
-# ifndef SFRAME_FRE_RA_TRACKING
-# define SFRAME_FRE_RA_TRACKING 1
-# endif
-#endif
-
 /* SFrame FRE type selection optimization is an optimization for size.
 
    There are three flavors of SFrame FRE representation in the binary format:
@@ -154,7 +142,6 @@ sframe_fre_set_cfa_offset (struct sframe_row_entry *fre,
   fre->merge_candidate = false;
 }
 
-#ifdef SFRAME_FRE_RA_TRACKING
 static void
 sframe_fre_set_ra_track (struct sframe_row_entry *fre, offsetT ra_offset)
 {
@@ -162,7 +149,6 @@ sframe_fre_set_ra_track (struct sframe_row_entry *fre, offsetT ra_offset)
   fre->ra_offset = ra_offset;
   fre->merge_candidate = false;
 }
-#endif
 
 static void
 sframe_fre_set_bp_track (struct sframe_row_entry *fre, offsetT bp_offset)
@@ -352,11 +338,9 @@ get_fre_num_offsets (struct sframe_row_entry *sframe_fre)
 
   if (sframe_fre->bp_loc == SFRAME_FRE_ELEM_LOC_STACK)
     fre_num_offsets++;
-#ifdef SFRAME_FRE_RA_TRACKING
   if (sframe_ra_tracking_p ()
       && sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK)
     fre_num_offsets++;
-#endif
   return fre_num_offsets;
 }
 
@@ -377,11 +361,9 @@ sframe_get_fre_offset_size (struct sframe_row_entry *sframe_fre)
   cfa_offset_size = get_offset_size_in_bytes (sframe_fre->cfa_offset);
   if (sframe_fre->bp_loc == SFRAME_FRE_ELEM_LOC_STACK)
     bp_offset_size = get_offset_size_in_bytes (sframe_fre->bp_offset);
-#ifdef SFRAME_FRE_RA_TRACKING
   if (sframe_ra_tracking_p ()
       && sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK)
     ra_offset_size = get_offset_size_in_bytes (sframe_fre->ra_offset);
-#endif
 
   /* Get the maximum size needed to represent the offsets.  */
   max_offset_size = cfa_offset_size;
@@ -587,14 +569,12 @@ output_sframe_row_entry (symbolS *fde_start_addr,
   fre_offset_func_map[idx].out_func (sframe_fre->cfa_offset);
   fre_write_offsets++;
 
-#ifdef SFRAME_FRE_RA_TRACKING
   if (sframe_ra_tracking_p ()
       && sframe_fre->ra_loc == SFRAME_FRE_ELEM_LOC_STACK)
     {
       fre_offset_func_map[idx].out_func (sframe_fre->ra_offset);
       fre_write_offsets++;
     }
-#endif
   if (sframe_fre->bp_loc == SFRAME_FRE_ELEM_LOC_STACK)
     {
       fre_offset_func_map[idx].out_func (sframe_fre->bp_offset);
@@ -688,9 +668,9 @@ output_sframe_internal (void)
 
   unsigned int num_fdes = get_num_sframe_fdes ();
   unsigned int num_fres = get_num_sframe_fres ();
-  symbolS **fre_symbols = XNEWVEC (symbolS *, num_fres);
-  for (i = 0; i < num_fres; i++)
-    fre_symbols[i] = symbol_temp_make ();
+  symbolS **fde_fre_symbols = XNEWVEC (symbolS *, num_fdes);
+  for (i = 0; i < num_fdes; i++)
+    fde_fre_symbols[i] = symbol_temp_make ();
 
   end_of_frame_hdr = symbol_temp_make ();
   start_of_fre_section = symbol_temp_make ();
@@ -764,8 +744,8 @@ output_sframe_internal (void)
   for (sframe_fde = all_sframe_fdes; sframe_fde; sframe_fde = sframe_fde->next)
     {
       output_sframe_funcdesc (start_of_fre_section,
-			      fre_symbols[i], sframe_fde);
-      i += sframe_fde->num_fres;
+			      fde_fre_symbols[i], sframe_fde);
+      i++;
     }
 
   symbol_set_value_now (start_of_fre_section);
@@ -776,16 +756,16 @@ output_sframe_internal (void)
 
   for (sframe_fde = all_sframe_fdes; sframe_fde; sframe_fde = sframe_fde_next)
     {
+      symbol_set_value_now (fde_fre_symbols[i]);
       for (sframe_fre = sframe_fde->sframe_fres;
 	   sframe_fre;
 	   sframe_fre = sframe_fre->next)
 	{
-	  symbol_set_value_now (fre_symbols[i]);
 	  output_sframe_row_entry (get_dw_fde_start_addrS (sframe_fde->dw_fde),
 				   get_dw_fde_end_addrS (sframe_fde->dw_fde),
 				   sframe_fre);
-	  i++;
 	}
+      i++;
       sframe_fde_next = sframe_fde->next;
       sframe_fde_free (sframe_fde);
     }
@@ -794,10 +774,10 @@ output_sframe_internal (void)
 
   symbol_set_value_now (end_of_frame_section);
 
-  gas_assert (i == num_fres);
+  gas_assert (i == num_fdes);
 
-  free (fre_symbols);
-  fre_symbols = NULL;
+  free (fde_fre_symbols);
+  fde_fre_symbols = NULL;
 }
 
 static unsigned int
@@ -926,10 +906,8 @@ sframe_register_name (unsigned int reg)
     return "SP";
   else if (reg == SFRAME_CFA_FP_REG)
     return "FP";
-#ifdef SFRAME_FRE_RA_TRACKING
   else if (reg == SFRAME_CFA_RA_REG)
     return "RA";
-#endif
   else
     return NULL;
 }
@@ -1003,7 +981,8 @@ sframe_xlate_do_def_cfa (struct sframe_xlate_ctx *xlate_ctx,
   if (cfi_insn->u.ri.reg != SFRAME_CFA_SP_REG
       && cfi_insn->u.ri.reg != SFRAME_CFA_FP_REG)
     {
-      as_warn (_("skipping SFrame FDE; non-SP/FP register %u in .cfi_def_cfa"),
+      as_warn (_("no SFrame FDE emitted; "
+		 "non-SP/FP register %u in .cfi_def_cfa"),
 	       cfi_insn->u.ri.reg);
       return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
     }
@@ -1032,7 +1011,7 @@ sframe_xlate_do_def_cfa_register (struct sframe_xlate_ctx *xlate_ctx,
   if (cfi_insn->u.r != SFRAME_CFA_SP_REG
       && cfi_insn->u.r != SFRAME_CFA_FP_REG)
     {
-      as_warn (_("skipping SFrame FDE; "
+      as_warn (_("no SFrame FDE emitted; "
 		 "non-SP/FP register %u in .cfi_def_cfa_register"),
 	       cfi_insn->u.r);
       return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
@@ -1072,7 +1051,7 @@ sframe_xlate_do_def_cfa_offset (struct sframe_xlate_ctx *xlate_ctx,
     {
       /* No CFA base register in effect.  Non-SP/FP CFA base register should
 	 not occur, as sframe_xlate_do_def_cfa[_register] would detect this.  */
-      as_warn (_("skipping SFrame FDE; "
+      as_warn (_("no SFrame FDE emitted; "
 		 ".cfi_def_cfa_offset without CFA base register in effect"));
       return SFRAME_XLATE_ERR_NOTREPRESENTED;
     }
@@ -1102,14 +1081,12 @@ sframe_xlate_do_offset (struct sframe_xlate_ctx *xlate_ctx,
       sframe_fre_set_bp_track (cur_fre, cfi_insn->u.ri.offset);
       cur_fre->merge_candidate = false;
     }
-#ifdef SFRAME_FRE_RA_TRACKING
   else if (sframe_ra_tracking_p ()
 	   && cfi_insn->u.ri.reg == SFRAME_CFA_RA_REG)
     {
       sframe_fre_set_ra_track (cur_fre, cfi_insn->u.ri.offset);
       cur_fre->merge_candidate = false;
     }
-#endif
   /* This is used to track changes to non-rsp registers, skip all others
      except FP / RA for now.  */
   return SFRAME_XLATE_OK;
@@ -1131,13 +1108,11 @@ sframe_xlate_do_val_offset (const struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_U
      DW_CFA_val_offset instruction can be safely skipped without sacrificing
      the asynchronicity of stack trace information.  */
   if (cfi_insn->u.ri.reg == SFRAME_CFA_FP_REG
-#ifdef SFRAME_FRE_RA_TRACKING
       || (sframe_ra_tracking_p () && cfi_insn->u.ri.reg == SFRAME_CFA_RA_REG)
-#endif
       /* Ignore SP reg, if offset matches assumed default rule.  */
       || (cfi_insn->u.ri.reg == SFRAME_CFA_SP_REG && cfi_insn->u.ri.offset != 0))
     {
-      as_warn (_("skipping SFrame FDE; %s with %s reg %u"),
+      as_warn (_("no SFrame FDE emitted; %s with %s reg %u"),
 	       cfi_esc_p ? ".cfi_escape DW_CFA_val_offset" : ".cfi_val_offset",
 	       sframe_register_name (cfi_insn->u.ri.reg), cfi_insn->u.ri.reg);
       return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
@@ -1159,13 +1134,11 @@ sframe_xlate_do_register (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
      instruction can be safely skipped without sacrificing the asynchronicity of
      stack trace information.  */
   if (cfi_insn->u.rr.reg1 == SFRAME_CFA_FP_REG
-#ifdef SFRAME_FRE_RA_TRACKING
       || (sframe_ra_tracking_p () && cfi_insn->u.rr.reg1 == SFRAME_CFA_RA_REG)
-#endif
       /* Ignore SP reg, as it can be recovered from the CFA tracking info.  */
       )
     {
-      as_warn (_("skipping SFrame FDE; %s register %u in .cfi_register"),
+      as_warn (_("no SFrame FDE emitted; %s register %u in .cfi_register"),
 	       sframe_register_name (cfi_insn->u.rr.reg1), cfi_insn->u.rr.reg1);
       return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
     }
@@ -1187,7 +1160,7 @@ sframe_xlate_do_remember_state (struct sframe_xlate_ctx *xlate_ctx)
      info for the function involved.  */
   if (!last_fre)
     {
-      as_warn (_("skipping SFrame FDE; "
+      as_warn (_("no SFrame FDE emitted; "
 		 ".cfi_remember_state without prior SFrame FRE state"));
       return SFRAME_XLATE_ERR_INVAL;
     }
@@ -1246,7 +1219,6 @@ sframe_xlate_do_restore (struct sframe_xlate_ctx *xlate_ctx,
       cur_fre->bp_offset = cie_fre->bp_offset;
       cur_fre->merge_candidate = false;
     }
-#ifdef SFRAME_FRE_RA_TRACKING
   else if (sframe_ra_tracking_p ()
 	   && cfi_insn->u.r == SFRAME_CFA_RA_REG)
     {
@@ -1255,7 +1227,6 @@ sframe_xlate_do_restore (struct sframe_xlate_ctx *xlate_ctx,
       cur_fre->ra_offset = cie_fre->ra_offset;
       cur_fre->merge_candidate = false;
     }
-#endif
   return SFRAME_XLATE_OK;
 }
 
@@ -1283,7 +1254,7 @@ static int
 sframe_xlate_do_aarch64_negate_ra_state_with_pc (struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
 						 struct cfi_insn_data *cfi_insn ATTRIBUTE_UNUSED)
 {
-  as_warn (_("skipping SFrame FDE; .cfi_negate_ra_state_with_pc"));
+  as_warn (_("no SFrame FDE emitted; .cfi_negate_ra_state_with_pc"));
   /* The used signing method should be encoded inside the FDE in SFrame v3.
      For now, PAuth_LR extension is not supported with SFrame.  */
   return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
@@ -1310,7 +1281,7 @@ sframe_xlate_do_gnu_window_save (struct sframe_xlate_ctx *xlate_ctx,
       || abi_arch == SFRAME_ABI_AARCH64_ENDIAN_LITTLE)
     return sframe_xlate_do_aarch64_negate_ra_state (xlate_ctx, cfi_insn);
 
-  as_warn (_("skipping SFrame FDE; .cfi_window_save"));
+  as_warn (_("no SFrame FDE emitted; .cfi_window_save"));
   return SFRAME_XLATE_ERR_NOTREPRESENTED;  /* Not represented.  */
 }
 
@@ -1365,12 +1336,10 @@ sframe_xlate_do_escape_expr (const struct sframe_xlate_ctx *xlate_ctx,
 #undef CFI_ESC_NUM_EXP
 
   if (reg == SFRAME_CFA_SP_REG || reg == SFRAME_CFA_FP_REG
-#ifdef SFRAME_FRE_RA_TRACKING
       || (sframe_ra_tracking_p () && reg == SFRAME_CFA_RA_REG)
-#endif
       || reg == xlate_ctx->cur_fre->cfa_base_reg)
     {
-      as_warn (_("skipping SFrame FDE; "
+      as_warn (_("no SFrame FDE emitted; "
 		 ".cfi_escape DW_CFA_expression with %s reg %u"),
 	       sframe_register_name (reg), reg);
       err = SFRAME_XLATE_ERR_NOTREPRESENTED;
@@ -1531,7 +1500,7 @@ sframe_xlate_do_cfi_escape (const struct sframe_xlate_ctx *xlate_ctx,
 	 OS-specific CFI opcodes), skip inspecting the DWARF expression.
 	 This may impact the asynchronicity due to loss of coverage.
 	 Continue to warn the user and bail out.  */
-      as_warn (_("skipping SFrame FDE; .cfi_escape with op (%#lx)"),
+      as_warn (_("no SFrame FDE emitted; .cfi_escape with op (%#lx)"),
 	       (unsigned long)firstop);
       err = SFRAME_XLATE_ERR_NOTREPRESENTED;
     }
@@ -1539,6 +1508,89 @@ sframe_xlate_do_cfi_escape (const struct sframe_xlate_ctx *xlate_ctx,
   return err;
 }
 
+/* Translate DW_CFA_undefined into SFrame context.
+
+   DW_CFA_undefined op indicates that from now on, the previous value of
+   register can’t be restored anymore.  In SFrame stack trace, we cannot
+   represent such a semantic.  So, we skip generating an SFrame FDE for this,
+   when a register of interest is used with DW_CFA_undefined.
+
+   Return SFRAME_XLATE_OK if success.  */
+
+static int
+sframe_xlate_do_cfi_undefined (const struct sframe_xlate_ctx *xlate_ctx ATTRIBUTE_UNUSED,
+			       const struct cfi_insn_data *cfi_insn)
+{
+  if (cfi_insn->u.r == SFRAME_CFA_FP_REG
+      || cfi_insn->u.r == SFRAME_CFA_RA_REG
+      || cfi_insn->u.r == SFRAME_CFA_SP_REG)
+    {
+      as_warn (_("no SFrame FDE emitted; %s reg %u in .cfi_undefined"),
+	       sframe_register_name (cfi_insn->u.r), cfi_insn->u.r);
+      return SFRAME_XLATE_ERR_NOTREPRESENTED; /* Not represented.  */
+    }
+
+  /* Safe to skip.  */
+  return SFRAME_XLATE_OK;
+}
+
+/* Translate DW_CFA_same_value into SFrame context.
+
+   DW_CFA_same_value op indicates that current value of register is the same as
+   in the previous frame, i.e. no restoration needed.  In SFrame stack trace
+   format, the handling is done similar to DW_CFA_restore.
+
+   For SFRAME_CFA_RA_REG, if RA-tracking is enabled, reset the SFrame FRE state
+   for REG_RA to indicate that register does not need restoration.  P.S.: Even
+   though resetting just REG_RA may be contradicting the AArch64 ABI (as Frame
+   Record contains for FP and LR), sframe_xlate_do_same_value () does not
+   detect the case and assumes the users' DW_CFA_same_value SFRAME_CFA_RA_REG
+   has a sound reason.  For ABIs, where RA-tracking is disabled, handle it
+   similar to DW_CFA_restore: ignore the directive, it is safe to skip.  The
+   reasoning is similar to that for DW_CFA_restore: if such a restoration was
+   meant to be of any consequence, there must have been the necessary CFI
+   directives for updating the CFA rule too such that the recovered RA from
+   stack is valid.
+
+   SFrame based stacktracers will implement CFA-based SP recovery for all ABIs:
+   SP for previous frame is based on the applicable CFA-rule.  There is no
+   representation in SFrame to indicate "no restoration needed" for REG_SP,
+   when going to the previous frame.  That said, if DW_CFA_same_value is seen
+   for SFRAME_CFA_SP_REG, handle it similar to DW_CFA_restore: ignore the
+   directive, it is safe to skip.  The reasoning is similar to that for
+   DW_CFA_restore: if such a restoration was meant to be of any consequence,
+   there must have been the necessary CFI directives for updating the CFA rule
+   too.  The latter will be duly processed by the SFrame generation code, as
+   expected.
+
+   For SFRAME_CFA_FP_REG, reset the state of the current FRE to indicate that
+   the value is the same as previous frame.
+
+   Return SFRAME_XLATE_OK if success.  */
+
+static int
+sframe_xlate_do_same_value (const struct sframe_xlate_ctx *xlate_ctx,
+			    const struct cfi_insn_data *cfi_insn)
+{
+  struct sframe_row_entry *cur_fre = xlate_ctx->cur_fre;
+
+  if (sframe_ra_tracking_p () && cfi_insn->u.r == SFRAME_CFA_RA_REG)
+    {
+      cur_fre->ra_loc = SFRAME_FRE_ELEM_LOC_REG;
+      cur_fre->ra_offset = 0;
+      cur_fre->merge_candidate = false;
+    }
+  else if (cfi_insn->u.r == SFRAME_CFA_FP_REG)
+    {
+      cur_fre->bp_loc = SFRAME_FRE_ELEM_LOC_REG;
+      cur_fre->bp_offset = 0;
+      cur_fre->merge_candidate = false;
+    }
+
+  /* Safe to skip.  */
+  return SFRAME_XLATE_OK;
+}
+
 /* Returns the DWARF call frame instruction name or fake CFI name for the
    specified CFI opcode, or NULL if the value is not recognized.  */
 
@@ -1638,11 +1690,11 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
     case CFI_escape:
       err = sframe_xlate_do_cfi_escape (xlate_ctx, cfi_insn);
       break;
-    /* Following CFI opcodes are not processed at this time.
-       These do not impact the coverage of the basic stack tracing
-       information as conveyed in the SFrame format.  */
     case DW_CFA_undefined:
+      err = sframe_xlate_do_cfi_undefined (xlate_ctx, cfi_insn);
+      break;
     case DW_CFA_same_value:
+      err = sframe_xlate_do_same_value (xlate_ctx, cfi_insn);
       break;
     default:
       /* Other skipped operations may, however, impact the asynchronicity.  */
@@ -1651,7 +1703,7 @@ sframe_do_cfi_insn (struct sframe_xlate_ctx *xlate_ctx,
 
 	if (!cfi_name)
 	  cfi_name = _("(unknown)");
-	as_warn (_("skipping SFrame FDE; CFI insn %s (%#x)"),
+	as_warn (_("no SFrame FDE emitted; CFI insn %s (%#x)"),
 		 cfi_name, op);
 	err = SFRAME_XLATE_ERR_NOTREPRESENTED;
       }
@@ -1675,7 +1727,7 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
   /* SFrame format cannot represent a non-default DWARF return column reg.  */
   if (xlate_ctx->dw_fde->return_column != DWARF2_DEFAULT_RETURN_COLUMN)
     {
-      as_warn (_("skipping SFrame FDE; non-default RA register %u"),
+      as_warn (_("no SFrame FDE emitted; non-default RA register %u"),
 	       xlate_ctx->dw_fde->return_column);
       return SFRAME_XLATE_ERR_NOTREPRESENTED;
     }
@@ -1707,7 +1759,6 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
 	= get_dw_fde_end_addrS (xlate_ctx->dw_fde);
     }
 
-#ifdef SFRAME_FRE_RA_TRACKING
   if (sframe_ra_tracking_p ())
     {
       struct sframe_row_entry *fre;
@@ -1719,12 +1770,11 @@ sframe_do_fde (struct sframe_xlate_ctx *xlate_ctx,
 	  if (fre->ra_loc != SFRAME_FRE_ELEM_LOC_STACK
 	      && fre->bp_loc == SFRAME_FRE_ELEM_LOC_STACK)
 	    {
-	      as_warn (_("skipping SFrame FDE; FP without RA on stack"));
+	      as_warn (_("no SFrame FDE emitted; FP without RA on stack"));
 	      return SFRAME_XLATE_ERR_NOTREPRESENTED;
 	    }
 	}
     }
-#endif /* SFRAME_FRE_RA_TRACKING  */
 
   return SFRAME_XLATE_OK;
 }