From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 1039) id 1F5ED3858422; Thu, 18 Nov 2021 16:26:03 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1F5ED3858422 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: H.J. Lu To: gcc-cvs@gcc.gnu.org Subject: [gcc r12-5377] x86: Add -mindirect-branch-cs-prefix X-Act-Checkin: gcc X-Git-Author: H.J. Lu X-Git-Refname: refs/heads/master X-Git-Oldrev: ca243ada71656651a8753e88164a1f0f019be1c3 X-Git-Newrev: 2196a681d7810ad8b227bf983f38ba716620545e Message-Id: <20211118162603.1F5ED3858422@sourceware.org> Date: Thu, 18 Nov 2021 16:26:03 +0000 (GMT) X-BeenThere: gcc-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 18 Nov 2021 16:26:03 -0000 https://gcc.gnu.org/g:2196a681d7810ad8b227bf983f38ba716620545e commit r12-5377-g2196a681d7810ad8b227bf983f38ba716620545e Author: H.J. Lu Date: Wed Oct 27 06:27:15 2021 -0700 x86: Add -mindirect-branch-cs-prefix Add -mindirect-branch-cs-prefix to add CS prefix to call and jmp to indirect thunk with branch target in r8-r15 registers so that the call and jmp instruction length is 6 bytes to allow them to be replaced with "lfence; call *%r8-r15" or "lfence; jmp *%r8-r15" at run-time. gcc/ PR target/102952 * config/i386/i386.c (ix86_output_jmp_thunk_or_indirect): Emit CS prefix for -mindirect-branch-cs-prefix. (ix86_output_indirect_branch_via_reg): Likewise. * config/i386/i386.opt: Add -mindirect-branch-cs-prefix. * doc/invoke.texi: Document -mindirect-branch-cs-prefix. gcc/testsuite/ PR target/102952 * gcc.target/i386/indirect-thunk-cs-prefix-1.c: New test. * gcc.target/i386/indirect-thunk-cs-prefix-2.c: Likewise. Diff: --- gcc/config/i386/i386.c | 6 ++++++ gcc/config/i386/i386.opt | 4 ++++ gcc/doc/invoke.texi | 10 +++++++++- .../gcc.target/i386/indirect-thunk-cs-prefix-1.c | 14 ++++++++++++++ .../gcc.target/i386/indirect-thunk-cs-prefix-2.c | 15 +++++++++++++++ 5 files changed, 48 insertions(+), 1 deletion(-) diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c index c246c8736f5..7fe271b1b94 100644 --- a/gcc/config/i386/i386.c +++ b/gcc/config/i386/i386.c @@ -15982,6 +15982,9 @@ ix86_output_jmp_thunk_or_indirect (const char *thunk_name, const int regno) { if (thunk_name != NULL) { + if (REX_INT_REGNO_P (regno) + && ix86_indirect_branch_cs_prefix) + fprintf (asm_out_file, "\tcs\n"); fprintf (asm_out_file, "\tjmp\t"); assemble_name (asm_out_file, thunk_name); putc ('\n', asm_out_file); @@ -16031,6 +16034,9 @@ ix86_output_indirect_branch_via_reg (rtx call_op, bool sibcall_p) { if (thunk_name != NULL) { + if (REX_INT_REGNO_P (regno) + && ix86_indirect_branch_cs_prefix) + fprintf (asm_out_file, "\tcs\n"); fprintf (asm_out_file, "\tcall\t"); assemble_name (asm_out_file, thunk_name); putc ('\n', asm_out_file); diff --git a/gcc/config/i386/i386.opt b/gcc/config/i386/i386.opt index 2b6d8aab101..3e67c537bb7 100644 --- a/gcc/config/i386/i386.opt +++ b/gcc/config/i386/i386.opt @@ -1076,6 +1076,10 @@ Enum(indirect_branch) String(thunk-inline) Value(indirect_branch_thunk_inline) EnumValue Enum(indirect_branch) String(thunk-extern) Value(indirect_branch_thunk_extern) +mindirect-branch-cs-prefix +Target Var(ix86_indirect_branch_cs_prefix) Init(0) +Add CS prefix to call and jmp to indirect thunk with branch target in r8-r15 registers. + mindirect-branch-register Target Var(ix86_indirect_branch_register) Init(0) Force indirect call and jump via register. diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index d62ec08150e..5fed1dd6a31 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -1427,7 +1427,8 @@ 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 -mharden-sls=@var{choice} -mneeded} +-mindirect-branch-register -mharden-sls=@var{choice} @gol +-mindirect-branch-cs-prefix -mneeded} @emph{x86 Windows Options} @gccoptlist{-mconsole -mcygwin -mno-cygwin -mdll @gol @@ -32416,6 +32417,13 @@ hardening. @samp{return} enables SLS hardening for function return. @samp{indirect-branch} enables SLS hardening for indirect branch. @samp{all} enables all SLS hardening. +@item -mindirect-branch-cs-prefix +@opindex mindirect-branch-cs-prefix +Add CS prefix to call and jmp to indirect thunk with branch target in +r8-r15 registers so that the call and jmp instruction length is 6 bytes +to allow them to be replaced with @samp{lfence; call *%r8-r15} or +@samp{lfence; jmp *%r8-r15} at run-time. + @end table These @samp{-m} switches are supported in addition to the above diff --git a/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-1.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-1.c new file mode 100644 index 00000000000..db2f3416823 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-1.c @@ -0,0 +1,14 @@ +/* { dg-do compile { target { ! ia32 } } } */ +/* { dg-options "-O2 -ffixed-rax -ffixed-rbx -ffixed-rcx -ffixed-rdx -ffixed-rdi -ffixed-rsi -mindirect-branch-cs-prefix -mindirect-branch=thunk-extern" } */ +/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */ + +extern void (*fptr) (void); + +void +foo (void) +{ + fptr (); +} + +/* { dg-final { scan-assembler-times "jmp\[ \t\]+_?__x86_indirect_thunk_r\[0-9\]+" 1 } } */ +/* { dg-final { scan-assembler-times "\tcs" 1 } } */ diff --git a/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-2.c b/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-2.c new file mode 100644 index 00000000000..adfc39a49d4 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/indirect-thunk-cs-prefix-2.c @@ -0,0 +1,15 @@ +/* { dg-do compile { target { ! ia32 } } } */ +/* { dg-options "-O2 -ffixed-rax -ffixed-rbx -ffixed-rcx -ffixed-rdx -ffixed-rdi -ffixed-rsi -mindirect-branch-cs-prefix -mindirect-branch=thunk-extern" } */ +/* { dg-additional-options "-fno-pic" { target { ! *-*-darwin* } } } */ + +extern void (*bar) (void); + +int +foo (void) +{ + bar (); + return 0; +} + +/* { dg-final { scan-assembler-times "call\[ \t\]+_?__x86_indirect_thunk_r\[0-9\]+" 1 } } */ +/* { dg-final { scan-assembler-times "\tcs" 1 } } */