[v3] x86: Add -mharden-sls=[none|all|return|indirect-branch]
Commit Message
On Wed, Nov 17, 2021 at 7:53 AM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Wed, Nov 17, 2021 at 4:35 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > Add -mharden-sls= to mitigate against straight line speculation (SLS)
> > for function return and indirect branch by adding an INT3 instruction
> > after function return and indirect branch.
> >
> > gcc/
> >
> > PR target/102952
> > * config/i386/i386-opts.h (harden_sls): New enum.
> > * config/i386/i386.c (output_indirect_thunk): Mitigate against
> > SLS for function return.
> > (ix86_output_function_return): Likewise.
> > (ix86_output_jmp_thunk_or_indirect): Mitigate against indirect
> > branch.
> > (ix86_output_indirect_jmp): Likewise.
> > (ix86_output_call_insn): Likewise.
> > * config/i386/i386.opt: Add -mharden-sls=.
> > * doc/invoke.texi: Document -mharden-sls=.
> >
> > gcc/testsuite/
> >
> > PR target/102952
> > * gcc.target/i386/harden-sls-1.c: New test.
> > * gcc.target/i386/harden-sls-2.c: Likewise.
> > * gcc.target/i386/harden-sls-3.c: Likewise.
> > * gcc.target/i386/harden-sls-4.c: Likewise.
> > * gcc.target/i386/harden-sls-5.c: Likewise.
> > ---
> > gcc/config/i386/i386-opts.h | 7 ++++++
> > gcc/config/i386/i386.c | 23 ++++++++++++++------
> > gcc/config/i386/i386.opt | 20 +++++++++++++++++
> > gcc/doc/invoke.texi | 10 ++++++++-
> > gcc/testsuite/gcc.target/i386/harden-sls-1.c | 14 ++++++++++++
> > gcc/testsuite/gcc.target/i386/harden-sls-2.c | 14 ++++++++++++
> > gcc/testsuite/gcc.target/i386/harden-sls-3.c | 14 ++++++++++++
> > gcc/testsuite/gcc.target/i386/harden-sls-4.c | 16 ++++++++++++++
> > gcc/testsuite/gcc.target/i386/harden-sls-5.c | 17 +++++++++++++++
> > 9 files changed, 127 insertions(+), 8 deletions(-)
> > create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-1.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-2.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-3.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-4.c
> > create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-5.c
> >
> > diff --git a/gcc/config/i386/i386-opts.h b/gcc/config/i386/i386-opts.h
> > index 04e4ad608fb..171d3106d0a 100644
> > --- a/gcc/config/i386/i386-opts.h
> > +++ b/gcc/config/i386/i386-opts.h
> > @@ -121,4 +121,11 @@ enum instrument_return {
> > instrument_return_nop5
> > };
> >
> > +enum harden_sls {
> > + harden_sls_none = 0,
> > + harden_sls_return = 1 << 0,
> > + harden_sls_indirect_branch = 1 << 1,
> > + harden_sls_all = harden_sls_return | harden_sls_indirect_branch
> > +};
> > +
> > #endif
> > diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> > index 73c4d5115bb..8bbf6ae9875 100644
> > --- a/gcc/config/i386/i386.c
> > +++ b/gcc/config/i386/i386.c
> > @@ -5914,6 +5914,8 @@ output_indirect_thunk (unsigned int regno)
> > }
> >
> > fputs ("\tret\n", asm_out_file);
> > + if ((ix86_harden_sls & harden_sls_return))
> > + fputs ("\tint3\n", asm_out_file);
> > }
> >
> > /* Output a funtion with a call and return thunk for indirect branch.
> > @@ -15984,6 +15986,8 @@ ix86_output_jmp_thunk_or_indirect (const char *thunk_name, const int regno)
> > fprintf (asm_out_file, "\tjmp\t");
> > assemble_name (asm_out_file, thunk_name);
> > putc ('\n', asm_out_file);
> > + if ((ix86_harden_sls & harden_sls_indirect_branch))
> > + fputs ("\tint3\n", asm_out_file);
> > }
> > else
> > output_indirect_thunk (regno);
> > @@ -16206,10 +16210,10 @@ ix86_output_indirect_jmp (rtx call_op)
> > gcc_unreachable ();
> >
> > ix86_output_indirect_branch (call_op, "%0", true);
> > - return "";
> > }
> > else
> > - return "%!jmp\t%A0";
> > + output_asm_insn ("%!jmp\t%A0", &call_op);
> > + return (ix86_harden_sls & harden_sls_indirect_branch) ? "int3" : "";
> > }
> >
> > /* Output return instrumentation for current function if needed. */
> > @@ -16277,10 +16281,10 @@ ix86_output_function_return (bool long_p)
> > return "";
> > }
> >
> > - if (!long_p)
> > - return "%!ret";
> > -
> > - return "rep%; ret";
> > + if ((ix86_harden_sls & harden_sls_return))
> > + long_p = false;
>
> Is the above really needed? This will change "rep ret" to a "[notrack]
> ret" when SLS hardening is in effect, with a conditional [notrack]
> prefix, even when long ret was requested.
Fixed in the v3 patch.
> On a related note, "notrack ret" does not assemble for me, the
> assembler reports:
>
> notrack.s:1: Error: expecting indirect branch instruction after `notrack'
>
> Can you please clarify the above change?
I opened:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103307
Here is the v3 patch.
Comments
On Wed, Nov 17, 2021 at 9:02 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> On Wed, Nov 17, 2021 at 7:53 AM Uros Bizjak <ubizjak@gmail.com> wrote:
> >
> > On Wed, Nov 17, 2021 at 4:35 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > >
> > > Add -mharden-sls= to mitigate against straight line speculation (SLS)
> > > for function return and indirect branch by adding an INT3 instruction
> > > after function return and indirect branch.
> > >
> > > gcc/
> > >
> > > PR target/102952
> > > * config/i386/i386-opts.h (harden_sls): New enum.
> > > * config/i386/i386.c (output_indirect_thunk): Mitigate against
> > > SLS for function return.
> > > (ix86_output_function_return): Likewise.
> > > (ix86_output_jmp_thunk_or_indirect): Mitigate against indirect
> > > branch.
> > > (ix86_output_indirect_jmp): Likewise.
> > > (ix86_output_call_insn): Likewise.
> > > * config/i386/i386.opt: Add -mharden-sls=.
> > > * doc/invoke.texi: Document -mharden-sls=.
> > >
> > > gcc/testsuite/
> > >
> > > PR target/102952
> > > * gcc.target/i386/harden-sls-1.c: New test.
> > > * gcc.target/i386/harden-sls-2.c: Likewise.
> > > * gcc.target/i386/harden-sls-3.c: Likewise.
> > > * gcc.target/i386/harden-sls-4.c: Likewise.
> > > * gcc.target/i386/harden-sls-5.c: Likewise.
OK, with a small nit below.
Thanks,
Uros.
+mharden-sls=
+Target RejectNegative Joined Enum(harden_sls) Var(ix86_harden_sls)
Init(harden_sls_none)
+Generate code to mitigate against straight line speculation.
+
+Enum
+Name(harden_sls) Type(enum harden_sls)
+Known choices for mitigation against straight line speculation with
-mharden-sls=:
+
+EnumValue
+Enum(harden_sls) String(none) Value(harden_sls_none)
+
+EnumValue
+Enum(harden_sls) String(all) Value(harden_sls_all)
Please move the above enum to the last enum.
+
+EnumValue
+Enum(harden_sls) String(return) Value(harden_sls_return)
+
+EnumValue
+Enum(harden_sls) String(indirect-branch) Value(harden_sls_indirect_branch)
+
On Wed, Nov 17, 2021 at 12:09 PM Uros Bizjak <ubizjak@gmail.com> wrote:
>
> On Wed, Nov 17, 2021 at 9:02 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> >
> > On Wed, Nov 17, 2021 at 7:53 AM Uros Bizjak <ubizjak@gmail.com> wrote:
> > >
> > > On Wed, Nov 17, 2021 at 4:35 PM H.J. Lu <hjl.tools@gmail.com> wrote:
> > > >
> > > > Add -mharden-sls= to mitigate against straight line speculation (SLS)
> > > > for function return and indirect branch by adding an INT3 instruction
> > > > after function return and indirect branch.
> > > >
> > > > gcc/
> > > >
> > > > PR target/102952
> > > > * config/i386/i386-opts.h (harden_sls): New enum.
> > > > * config/i386/i386.c (output_indirect_thunk): Mitigate against
> > > > SLS for function return.
> > > > (ix86_output_function_return): Likewise.
> > > > (ix86_output_jmp_thunk_or_indirect): Mitigate against indirect
> > > > branch.
> > > > (ix86_output_indirect_jmp): Likewise.
> > > > (ix86_output_call_insn): Likewise.
> > > > * config/i386/i386.opt: Add -mharden-sls=.
> > > > * doc/invoke.texi: Document -mharden-sls=.
> > > >
> > > > gcc/testsuite/
> > > >
> > > > PR target/102952
> > > > * gcc.target/i386/harden-sls-1.c: New test.
> > > > * gcc.target/i386/harden-sls-2.c: Likewise.
> > > > * gcc.target/i386/harden-sls-3.c: Likewise.
> > > > * gcc.target/i386/harden-sls-4.c: Likewise.
> > > > * gcc.target/i386/harden-sls-5.c: Likewise.
>
> OK, with a small nit below.
>
> Thanks,
> Uros.
>
> +mharden-sls=
> +Target RejectNegative Joined Enum(harden_sls) Var(ix86_harden_sls)
> Init(harden_sls_none)
> +Generate code to mitigate against straight line speculation.
> +
> +Enum
> +Name(harden_sls) Type(enum harden_sls)
> +Known choices for mitigation against straight line speculation with
> -mharden-sls=:
> +
> +EnumValue
> +Enum(harden_sls) String(none) Value(harden_sls_none)
> +
> +EnumValue
> +Enum(harden_sls) String(all) Value(harden_sls_all)
>
> Please move the above enum to the last enum.
>
> +
> +EnumValue
> +Enum(harden_sls) String(return) Value(harden_sls_return)
> +
> +EnumValue
> +Enum(harden_sls) String(indirect-branch) Value(harden_sls_indirect_branch)
> +
This is the v4 patch I am checking in.
Thanks.
From ed5e4a06b0488bff1fcdf218d93b54e0abf7ff3b Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 27 Oct 2021 07:48:54 -0700
Subject: [PATCH v3] x86: Add -mharden-sls=[none|all|return|indirect-branch]
Add -mharden-sls= to mitigate against straight line speculation (SLS)
for function return and indirect branch by adding an INT3 instruction
after function return and indirect branch.
gcc/
PR target/102952
* config/i386/i386-opts.h (harden_sls): New enum.
* config/i386/i386.c (output_indirect_thunk): Mitigate against
SLS for function return.
(ix86_output_function_return): Likewise.
(ix86_output_jmp_thunk_or_indirect): Mitigate against indirect
branch.
(ix86_output_indirect_jmp): Likewise.
(ix86_output_call_insn): Likewise.
* config/i386/i386.opt: Add -mharden-sls=.
* doc/invoke.texi: Document -mharden-sls=.
gcc/testsuite/
PR target/102952
* gcc.target/i386/harden-sls-1.c: New test.
* gcc.target/i386/harden-sls-2.c: Likewise.
* gcc.target/i386/harden-sls-3.c: Likewise.
* gcc.target/i386/harden-sls-4.c: Likewise.
* gcc.target/i386/harden-sls-5.c: Likewise.
---
gcc/config/i386/i386-opts.h | 7 +++++++
gcc/config/i386/i386.c | 21 +++++++++++++-------
gcc/config/i386/i386.opt | 20 +++++++++++++++++++
gcc/doc/invoke.texi | 10 +++++++++-
gcc/testsuite/gcc.target/i386/harden-sls-1.c | 14 +++++++++++++
gcc/testsuite/gcc.target/i386/harden-sls-2.c | 14 +++++++++++++
gcc/testsuite/gcc.target/i386/harden-sls-3.c | 14 +++++++++++++
gcc/testsuite/gcc.target/i386/harden-sls-4.c | 16 +++++++++++++++
gcc/testsuite/gcc.target/i386/harden-sls-5.c | 17 ++++++++++++++++
9 files changed, 125 insertions(+), 8 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-1.c
create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-2.c
create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-3.c
create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-4.c
create mode 100644 gcc/testsuite/gcc.target/i386/harden-sls-5.c
@@ -121,4 +121,11 @@ enum instrument_return {
instrument_return_nop5
};
+enum harden_sls {
+ harden_sls_none = 0,
+ harden_sls_return = 1 << 0,
+ harden_sls_indirect_branch = 1 << 1,
+ harden_sls_all = harden_sls_return | harden_sls_indirect_branch
+};
+
#endif
@@ -5914,6 +5914,8 @@ output_indirect_thunk (unsigned int regno)
}
fputs ("\tret\n", asm_out_file);
+ if ((ix86_harden_sls & harden_sls_return))
+ fputs ("\tint3\n", asm_out_file);
}
/* Output a funtion with a call and return thunk for indirect branch.
@@ -15984,6 +15986,8 @@ ix86_output_jmp_thunk_or_indirect (const char *thunk_name, const int regno)
fprintf (asm_out_file, "\tjmp\t");
assemble_name (asm_out_file, thunk_name);
putc ('\n', asm_out_file);
+ if ((ix86_harden_sls & harden_sls_indirect_branch))
+ fputs ("\tint3\n", asm_out_file);
}
else
output_indirect_thunk (regno);
@@ -16206,10 +16210,10 @@ ix86_output_indirect_jmp (rtx call_op)
gcc_unreachable ();
ix86_output_indirect_branch (call_op, "%0", true);
- return "";
}
else
- return "%!jmp\t%A0";
+ output_asm_insn ("%!jmp\t%A0", &call_op);
+ return (ix86_harden_sls & harden_sls_indirect_branch) ? "int3" : "";
}
/* Output return instrumentation for current function if needed. */
@@ -16277,10 +16281,8 @@ ix86_output_function_return (bool long_p)
return "";
}
- if (!long_p)
- return "%!ret";
-
- return "rep%; ret";
+ output_asm_insn (long_p ? "rep%; ret" : "ret", nullptr);
+ return (ix86_harden_sls & harden_sls_return) ? "int3" : "";
}
/* Output indirect function return. RET_OP is the function return
@@ -16375,7 +16377,12 @@ ix86_output_call_insn (rtx_insn *insn, rtx call_op)
if (output_indirect_p && !direct_p)
ix86_output_indirect_branch (call_op, xasm, true);
else
- output_asm_insn (xasm, &call_op);
+ {
+ output_asm_insn (xasm, &call_op);
+ if (!direct_p
+ && (ix86_harden_sls & harden_sls_indirect_branch))
+ return "int3";
+ }
return "";
}
@@ -1117,6 +1117,26 @@ mrecord-return
Target Var(ix86_flag_record_return) Init(0)
Generate a __return_loc section pointing to all return instrumentation code.
+mharden-sls=
+Target RejectNegative Joined Enum(harden_sls) Var(ix86_harden_sls) Init(harden_sls_none)
+Generate code to mitigate against straight line speculation.
+
+Enum
+Name(harden_sls) Type(enum harden_sls)
+Known choices for mitigation against straight line speculation with -mharden-sls=:
+
+EnumValue
+Enum(harden_sls) String(none) Value(harden_sls_none)
+
+EnumValue
+Enum(harden_sls) String(all) Value(harden_sls_all)
+
+EnumValue
+Enum(harden_sls) String(return) Value(harden_sls_return)
+
+EnumValue
+Enum(harden_sls) String(indirect-branch) Value(harden_sls_indirect_branch)
+
mavx512bf16
Target Mask(ISA2_AVX512BF16) Var(ix86_isa_flags2) Save
Support MMX, SSE, SSE2, SSE3, SSSE3, SSE4.1, SSE4.2, AVX, AVX2, AVX512F and
@@ -1427,7 +1427,7 @@ See RS/6000 and PowerPC Options.
-mstack-protector-guard-symbol=@var{symbol} @gol
-mgeneral-regs-only -mcall-ms2sysv-xlogues -mrelax-cmpxchg-loop @gol
-mindirect-branch=@var{choice} -mfunction-return=@var{choice} @gol
--mindirect-branch-register -mneeded}
+-mindirect-branch-register -mharden-sls=@var{choice} -mneeded}
@emph{x86 Windows Options}
@gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol
@@ -32401,6 +32401,14 @@ not be reachable in the large code model.
@opindex mindirect-branch-register
Force indirect call and jump via register.
+@item -mharden-sls=@var{choice}
+@opindex mharden-sls
+Generate code to mitigate against straight line speculation (SLS) with
+@var{choice}. The default is @samp{none} which disables all SLS
+hardening. @samp{return} enables SLS hardening for function return.
+@samp{indirect-branch} enables SLS hardening for indirect branch.
+@samp{all} enables all SLS hardening.
+
@end table
These @samp{-m} switches are supported in addition to the above
new file mode 100644
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mindirect-branch=thunk-extern -mharden-sls=all" } */
+/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */
+
+extern void foo (void);
+
+void
+bar (void)
+{
+ foo ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]+_?foo" } } */
+/* { dg-final { scan-assembler-not {int3} } } */
new file mode 100644
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mindirect-branch=thunk-extern -mharden-sls=all" } */
+/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */
+
+extern void (*fptr) (void);
+
+void
+foo (void)
+{
+ fptr ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]+_?__x86_indirect_thunk_(r|e)ax" } } */
+/* { dg-final { scan-assembler-times "int3" 1 } } */
new file mode 100644
@@ -0,0 +1,14 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mindirect-branch=thunk -mharden-sls=all" } */
+/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */
+
+extern void (*fptr) (void);
+
+void
+foo (void)
+{
+ fptr ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]+_?__x86_indirect_thunk_(r|e)ax" } } */
+/* { dg-final { scan-assembler-times "int3" 2 } } */
new file mode 100644
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mindirect-branch=keep -mharden-sls=all" } */
+/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */
+
+extern void (*fptr) (void);
+
+void
+foo (void)
+{
+ fptr ();
+}
+
+/* { dg-final { scan-assembler "jmp\[ \t\]+\\*_?fptr" { target { ! x32 } } } } */
+/* { dg-final { scan-assembler "movl\[ \t\]+fptr\\(%rip\\), %eax" { target x32 } } } */
+/* { dg-final { scan-assembler "jmp\[ \t\]+\\*%rax" { target x32 } } } */
+/* { dg-final { scan-assembler-times "int3" 1 } } */
new file mode 100644
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -mno-indirect-branch-register -mfunction-return=keep -mindirect-branch=thunk-extern -mharden-sls=return" } */
+/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */
+
+typedef void (*dispatch_t)(long offset);
+
+dispatch_t dispatch;
+
+int
+male_indirect_jump (long offset)
+{
+ dispatch(offset);
+ return 0;
+}
+
+/* { dg-final { scan-assembler-times "ret" 1 } } */
+/* { dg-final { scan-assembler-times "int3" 1 } } */
--
2.33.1