gcc7/gcc7-pfe-0022-Fix-unwinding-issues-when-pfe-is-enabled.patch

From e534bd23ac8d259768d67db6f876f75687b109e7 Mon Sep 17 00:00:00 2001
From: Giuliano Belinassi <gbelinassi@suse.de>
Date: Mon, 18 Oct 2021 18:00:28 -0300
Subject: [PATCH 22/22] Fix unwinding issues when pfe is enabled.

This patch has basically the same behaviour as 3dcea658c, but avoid
relying on the backend and CET mechanisms which are not implemented in
gcc-7.

gcc/ChangeLog
2021-10-18  Michael Matz  <matz@suse.de>

	* final.c (get_some_local_dynamic_name): Call
	emit_patchable_function_entry.
	* varasm.c (emit_patchable_function_entry): New.

gcc/testsuite/ChangeLog
2021-10-18  Giuliano Belinassi  <gbelinassi@suse.de>

	Backport from mainline
	2020-02-03  H.J. Lu  <hjl.tools@gmail.com>

	PR target/93492
	* gcc.target/i386/pr93492-1.c: New test.
	* gcc.target/i386/pr93492-2.c: Likewise.
	* gcc.target/i386/pr93492-3.c: Likewise.
	* gcc.target/i386/pr93492-4.c: Likewise.
	* gcc.target/i386/pr93492-5.c: Likewise.

Authored-by: Michael Matz <matz@suse.de>
---
 gcc/ChangeLog                             |  6 ++
 gcc/final.c                               |  4 +
 gcc/testsuite/gcc.target/i386/pr93492-1.c | 76 +++++++++++++++++++
 gcc/testsuite/gcc.target/i386/pr93492-2.c | 12 +++
 gcc/testsuite/gcc.target/i386/pr93492-3.c | 13 ++++
 gcc/testsuite/gcc.target/i386/pr93492-4.c | 11 +++
 gcc/testsuite/gcc.target/i386/pr93492-5.c | 12 +++
 gcc/varasm.c                              | 91 +++++++++++++----------
 8 files changed, 187 insertions(+), 38 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/i386/pr93492-1.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr93492-2.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr93492-3.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr93492-4.c
 create mode 100644 gcc/testsuite/gcc.target/i386/pr93492-5.c

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 51fed5508dc..537c343e6f1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2021-10-18  Michael Matz  <matz@suse.de>
+
+	* final.c (get_some_local_dynamic_name): Call
+	emit_patchable_function_entry.
+	* varasm.c (emit_patchable_function_entry): New.
+
 2019-11-14  Release Manager
 
 	* GCC 7.5.0 released.
diff --git a/gcc/final.c b/gcc/final.c
index 43743f05d84..53528620545 100644
--- a/gcc/final.c
+++ b/gcc/final.c
@@ -1745,6 +1745,8 @@ get_some_local_dynamic_name ()
   return 0;
 }
 
+void emit_patchable_function_entry (tree decl, bool before);
+
 /* Output assembler code for the start of a function,
    and initialize some of the variables in this file
    for the new function.  The label for the function and associated
@@ -1781,6 +1783,8 @@ final_start_function (rtx_insn *first, FILE *file,
   if (!dwarf2_debug_info_emitted_p (current_function_decl))
     dwarf2out_begin_prologue (0, 0, NULL);
 
+  emit_patchable_function_entry (current_function_decl, false);
+
 #ifdef LEAF_REG_REMAP
   if (crtl->uses_only_leaf_regs)
     leaf_renumber_regs (first);
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-1.c b/gcc/testsuite/gcc.target/i386/pr93492-1.c
new file mode 100644
index 00000000000..3383b0dc27b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93492-1.c
@@ -0,0 +1,76 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1" } */
+
+/* Note: this test only checks the instructions in the function bodies,
+   not the placement of the patch label or nops before the function.  */
+
+/*
+**f10_none:
+**	nop
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (1, 0)))
+f10_none (void)
+{
+}
+
+/*
+**f10_endbr:
+**	endbr(32|64)
+**	nop
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (1, 0)))
+f10_endbr (void)
+{
+}
+
+/*
+**f11_none:
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (1, 1)))
+f11_none (void)
+{
+}
+
+/*
+**f11_endbr:
+**	endbr(32|64)
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (1, 1)))
+f11_endbr (void)
+{
+}
+
+/*
+**f21_none:
+**	nop
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (2, 1)))
+f21_none (void)
+{
+}
+
+/*
+**f21_endbr:
+**	endbr(32|64)
+**	nop
+**	ret
+*/
+void
+__attribute__ ((patchable_function_entry (2, 1)))
+f21_endbr (void)
+{
+}
+
+/* { dg-final { scan-assembler "\.LPFE1:\n\tnop\n\trep ret" } } */
+/* { dg-final { scan-assembler "\.LPFE2:\n\tnop\n\trep ret" } } */
+/* { dg-final { scan-assembler "f11_none:\n\.LFB2:\n\t\.cfi_startproc\n\trep ret" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-2.c b/gcc/testsuite/gcc.target/i386/pr93492-2.c
new file mode 100644
index 00000000000..d52d7a41637
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93492-2.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1 -fasynchronous-unwind-tables -Wno-attributes" } */
+
+/* Test the placement of the .LPFE1 label.  */
+
+void
+__attribute__ ((cf_check,patchable_function_entry (1, 0)))
+f10_endbr (void)
+{
+}
+
+/* { dg-final { scan-assembler "\.cfi_startproc\n.*\.LPFE1:\n\tnop\n\trep ret" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-3.c b/gcc/testsuite/gcc.target/i386/pr93492-3.c
new file mode 100644
index 00000000000..a3ba22da17d
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93492-3.c
@@ -0,0 +1,13 @@
+/* { dg-do "compile" } */
+/* { dg-require-effective-target mfentry } */
+/* { dg-options "-O1 -mfentry -pg -fasynchronous-unwind-tables -Wno-attributes" } */
+
+/* Test the placement of the .LPFE1 label.  */
+
+void
+__attribute__ ((cf_check,patchable_function_entry (1, 0)))
+f10_endbr (void)
+{
+}
+
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n1:\tcall\t__fentry__\n.*\t(rep )?ret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-4.c b/gcc/testsuite/gcc.target/i386/pr93492-4.c
new file mode 100644
index 00000000000..d5bfc58f7d8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93492-4.c
@@ -0,0 +1,11 @@
+/* { dg-do "compile" } */
+/* { dg-options "-O1 -fpatchable-function-entry=1 -fasynchronous-unwind-tables -Wno-attributes" } */
+
+/* Test the placement of the .LPFE1 label.  */
+
+void
+foo (void)
+{
+}
+
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n\trep ret\n" } } */
diff --git a/gcc/testsuite/gcc.target/i386/pr93492-5.c b/gcc/testsuite/gcc.target/i386/pr93492-5.c
new file mode 100644
index 00000000000..69e706ff38e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr93492-5.c
@@ -0,0 +1,12 @@
+/* { dg-do "compile" } */
+/* { dg-require-effective-target mfentry } */
+/* { dg-options "-O1 -fpatchable-function-entry=1 -mfentry -pg -fasynchronous-unwind-tables -Wno-attributes" } */
+
+/* Test the placement of the .LPFE1 label.  */
+
+void
+foo (void)
+{
+}
+
+/* { dg-final { scan-assembler "\t\.cfi_startproc\n.*\.LPFE1:\n\tnop\n1:\tcall\t__fentry__\n.*\t(rep )?ret\n" } } */
diff --git a/gcc/varasm.c b/gcc/varasm.c
index 9e0e7c0976f..e197fbdaed5 100644
--- a/gcc/varasm.c
+++ b/gcc/varasm.c
@@ -1698,6 +1698,58 @@ get_fnname_from_decl (tree decl)
   return XSTR (x, 0);
 }
 
+/* Emit the patchable function entry NOPs for function DECL.
+   BEFORE is true if we should emit the nops in front of the function
+   label (i.e. before prologue), or the ones after the function label
+   (part of the prologue).  */
+void
+emit_patchable_function_entry (tree decl, bool before)
+{
+  unsigned short patch_area_size = crtl->patch_area_size;
+  unsigned short patch_area_entry = crtl->patch_area_entry;
+
+  tree patchable_function_entry_attr
+    = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl));
+  if (patchable_function_entry_attr)
+    {
+      tree pp_val = TREE_VALUE (patchable_function_entry_attr);
+      tree patchable_function_entry_value1 = TREE_VALUE (pp_val);
+
+      patch_area_size = tree_to_uhwi (patchable_function_entry_value1);
+      patch_area_entry = 0;
+      if (TREE_CHAIN (pp_val) != NULL_TREE)
+	{
+	  tree patchable_function_entry_value2
+	    = TREE_VALUE (TREE_CHAIN (pp_val));
+	  patch_area_entry = tree_to_uhwi (patchable_function_entry_value2);
+	}
+    }
+
+  if (patch_area_entry > patch_area_size)
+    {
+      if (patch_area_size > 0 && before)
+	warning (OPT_Wattributes, "patchable function entry > size");
+      patch_area_entry = 0;
+    }
+
+  if (before)
+    {
+      /* Emit the patching area before the entry label, if any.  */
+      if (patch_area_entry > 0)
+	targetm.asm_out.print_patchable_function_entry (asm_out_file,
+							patch_area_entry, true);
+    }
+  else
+    {
+      /* And the area after the label.  Record it if we haven't done so yet.  */
+      if (patch_area_size > patch_area_entry)
+	targetm.asm_out.print_patchable_function_entry (asm_out_file,
+							patch_area_size
+							- patch_area_entry,
+							patch_area_entry == 0);
+    }
+}
+
 /* Output assembler code for the constant pool of a function and associated
    with defining the name of the function.  DECL describes the function.
    NAME is the function's name.  For the constant pool, we use the current
@@ -1829,37 +1881,7 @@ assemble_start_function (tree decl, const char *fnname)
   if (DECL_PRESERVE_P (decl))
     targetm.asm_out.mark_decl_preserved (fnname);
 
-  unsigned short patch_area_size = crtl->patch_area_size;
-  unsigned short patch_area_entry = crtl->patch_area_entry;
-
-  tree patchable_function_entry_attr
-    = lookup_attribute ("patchable_function_entry", DECL_ATTRIBUTES (decl));
-  if (patchable_function_entry_attr)
-    {
-      tree pp_val = TREE_VALUE (patchable_function_entry_attr);
-      tree patchable_function_entry_value1 = TREE_VALUE (pp_val);
-
-      patch_area_size = tree_to_uhwi (patchable_function_entry_value1);
-      patch_area_entry = 0;
-      if (TREE_CHAIN (pp_val) != NULL_TREE)
-	{
-	  tree patchable_function_entry_value2
-	    = TREE_VALUE (TREE_CHAIN (pp_val));
-	  patch_area_entry = tree_to_uhwi (patchable_function_entry_value2);
-	}
-    }
-
-  if (patch_area_entry > patch_area_size)
-    {
-      if (patch_area_size > 0)
-	warning (OPT_Wattributes, "patchable function entry > size");
-      patch_area_entry = 0;
-    }
-
-  /* Emit the patching area before the entry label, if any.  */
-  if (patch_area_entry > 0)
-    targetm.asm_out.print_patchable_function_entry (asm_out_file,
-						    patch_area_entry, true);
+  emit_patchable_function_entry (decl, true);
 
   /* Do any machine/system dependent processing of the function name.  */
 #ifdef ASM_DECLARE_FUNCTION_NAME
@@ -1869,13 +1891,6 @@ assemble_start_function (tree decl, const char *fnname)
   ASM_OUTPUT_FUNCTION_LABEL (asm_out_file, fnname, current_function_decl);
 #endif /* ASM_DECLARE_FUNCTION_NAME */
 
-  /* And the area after the label.  Record it if we haven't done so yet.  */
-  if (patch_area_size > patch_area_entry)
-    targetm.asm_out.print_patchable_function_entry (asm_out_file,
-						    patch_area_size
-						    - patch_area_entry,
-						    patch_area_entry == 0);
-
   if (lookup_attribute ("no_split_stack", DECL_ATTRIBUTES (decl)))
     saw_no_split_stack = true;
 }
-- 
2.33.1