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blob b22e364aff5f3b21b800e5e0c4103e404b388a6e 5466 bytes (raw)
name: gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch 	 # note: path name is non-authoritative(*)

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'Retpoline' mitigation technique for Spectre (branch target injection)
[CVE-2017-5715]:

https://security.googleblog.com/2018/01/more-details-about-mitigations-for-cpu_4.html
https://support.google.com/faqs/answer/7625886
https://spectreattack.com/
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-5715

Patch copied from the 'retpoline-20180107' branch of upstream source repository
(please add new / update existing patches when new 'retpoline-xxxxxxxx' branch
appears):

http://git.infradead.org/users/dwmw2/gcc-retpoline.git

From f96e28553b0f2253184441f22852d76976e19968 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 12 Dec 2017 19:15:25 -0800
Subject: [PATCH 15/17] Disable red zone with local indirect jump

---
 gcc/config/i386/i386-protos.h |  2 +-
 gcc/config/i386/i386.c        | 22 +++++++++++++++++-----
 gcc/config/i386/i386.h        |  4 ++++
 gcc/config/i386/i386.md       |  8 +++++---
 4 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index 213663811de..a78bfa00427 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -315,7 +315,7 @@ extern enum attr_cpu ix86_schedule;
 #endif
 
 extern const char * ix86_output_call_insn (rtx_insn *insn, rtx call_op);
-extern const char * ix86_output_indirect_jmp (rtx call_op);
+extern const char * ix86_output_indirect_jmp (rtx call_op, bool ret_p);
 extern const char * ix86_output_function_return (bool long_p);
 extern bool ix86_operands_ok_for_move_multiple (rtx *operands, bool load,
 						enum machine_mode mode);
diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
index 7ae3523095c..344cafe3dac 100644
--- a/gcc/config/i386/i386.c
+++ b/gcc/config/i386/i386.c
@@ -4209,12 +4209,19 @@ make_pass_stv (gcc::context *ctxt)
   return new pass_stv (ctxt);
 }
 
-/* Return true if a red-zone is in use.  */
+/* Return true if a red-zone is in use.  We can't use red-zone when
+   there are local indirect jumps, like "indirect_jump" or "tablejump",
+   which jumps to another place in the function, since "call" in the
+   indirect thunk pushes the return address onto stack, destroying
+   red-zone.  */
 
 bool
 ix86_using_red_zone (void)
 {
-  return TARGET_RED_ZONE && !TARGET_64BIT_MS_ABI;
+  return (TARGET_RED_ZONE
+	  && !TARGET_64BIT_MS_ABI
+	  && (!cfun->machine->has_local_indirect_jump
+	      || cfun->machine->indirect_branch_type == indirect_branch_keep));
 }
 \f
 /* Return a string that documents the current -m options.  The caller is
@@ -28919,11 +28926,16 @@ ix86_output_indirect_branch (rtx call_op, const char *xasm,
 }
 
 const char *
-ix86_output_indirect_jmp (rtx call_op)
+ix86_output_indirect_jmp (rtx call_op, bool ret_p)
 {
-  if (ix86_red_zone_size == 0
-      && cfun->machine->indirect_branch_type != indirect_branch_keep)
+  if (cfun->machine->indirect_branch_type != indirect_branch_keep)
     {
+      /* We can't have red-zone if this isn't a function return since
+	 "call" in the indirect thunk pushes the return address onto
+	 stack, destroying red-zone.  */
+      if (!ret_p && ix86_red_zone_size != 0)
+	gcc_unreachable ();
+
       ix86_output_indirect_branch (call_op, "%0", true);
       return "";
     }
diff --git a/gcc/config/i386/i386.h b/gcc/config/i386/i386.h
index f248f3ba2f5..5f30d3f8d19 100644
--- a/gcc/config/i386/i386.h
+++ b/gcc/config/i386/i386.h
@@ -2607,6 +2607,10 @@ struct GTY(()) machine_function {
   /* How to generate indirec branch.  */
   ENUM_BITFIELD(indirect_branch) indirect_branch_type : 3;
 
+  /* If true, the current function has local indirect jumps, like
+     "indirect_jump" or "tablejump".  */
+  BOOL_BITFIELD has_local_indirect_jump : 1;
+
   /* How to generate function return.  */
   ENUM_BITFIELD(indirect_branch) function_return_type : 3;
 
diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 473fa5c089b..ea95aad7540 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -11610,12 +11610,13 @@
 {
   if (TARGET_X32 || ix86_indirect_branch_thunk_register)
     operands[0] = convert_memory_address (word_mode, operands[0]);
+  cfun->machine->has_local_indirect_jump = true;
 })
 
 (define_insn "*indirect_jump"
   [(set (pc) (match_operand:W 0 "indirect_branch_operand" "rBw"))]
   ""
-  "* return ix86_output_indirect_jmp (operands[0]);"
+  "* return ix86_output_indirect_jmp (operands[0], false);"
   [(set_attr "type" "ibr")
    (set_attr "length_immediate" "0")
    (set_attr "maybe_prefix_bnd" "1")])
@@ -11659,13 +11660,14 @@
 
   if (TARGET_X32 || ix86_indirect_branch_thunk_register)
     operands[0] = convert_memory_address (word_mode, operands[0]);
+  cfun->machine->has_local_indirect_jump = true;
 })
 
 (define_insn "*tablejump_1"
   [(set (pc) (match_operand:W 0 "indirect_branch_operand" "rBw"))
    (use (label_ref (match_operand 1)))]
   ""
-  "* return ix86_output_indirect_jmp (operands[0]);"
+  "* return ix86_output_indirect_jmp (operands[0], false);"
   [(set_attr "type" "ibr")
    (set_attr "length_immediate" "0")
    (set_attr "maybe_prefix_bnd" "1")])
@@ -12342,7 +12344,7 @@
   [(simple_return)
    (use (match_operand:SI 0 "register_operand" "r"))]
   "reload_completed"
-  "* return ix86_output_indirect_jmp (operands[0]);"
+  "* return ix86_output_indirect_jmp (operands[0], true);"
   [(set_attr "type" "ibr")
    (set_attr "length_immediate" "0")
    (set_attr "maybe_prefix_bnd" "1")])
-- 
2.15.1


debug log:

solving b22e364af ...
found b22e364af in https://yhetil.org/guix/877esksi62.fsf@gmail.com/

applying [1/1] https://yhetil.org/guix/877esksi62.fsf@gmail.com/
diff --git a/gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch b/gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch
new file mode 100644
index 000000000..b22e364af

1:39: trailing whitespace.
 
1:45: space before tab in indent.
 						enum machine_mode mode);
1:53: trailing whitespace.
 
1:60: trailing whitespace.
 
1:74: trailing whitespace.
 
Checking patch gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch...
Applied patch gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch cleanly.
warning: squelched 7 whitespace errors
warning: 12 lines add whitespace errors.

index at:
100644 b22e364aff5f3b21b800e5e0c4103e404b388a6e	gnu/packages/patches/gcc-retpoline-Disable-red-zone-with-local-indirect-jump.patch

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