Re: [PATCH][PR target/84066] Wrong shadow stack register size is saved for x32

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, Jan 30, 2018 at 6:38 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> On Tue, Jan 30, 2018 at 3:19 PM, Tsimbalist, Igor V
> <igor.v.tsimbalist@intel.com> wrote:
>> x32 is a 64-bit process with 32-bit software pointer and kernel may
>> place x32 shadow stack above 4GB.  We need to save and restore 64-bit
>> shadow stack register for x32. builtin jmp buf size is 5 pointers.  We
>> have space to save 64-bit shadow stack pointer: 32-bit SP, 32-bit FP,
>> 32-bit IP, 64-bit SSP for x32.
>>
>>         PR target/84066
>>         * gcc/config/i386/i386.md: Replace Pmode with word_mode in
>>         builtin_setjmp_setup and builtin_longjmp to support x32.
>>         * gcc/testsuite/gcc.target/i386/cet-sjlj-6.c: New test.
>>
>> Ok for trunk?
>
> LGTM, but please check the testcase with -mx32
> -maddress-mode={short,long} nevertheless to catch any incosistencies.
>

Speaking of -maddress-mode=, shouldn't

+      reg_adj = gen_rtx_SUBREG (Pmode, reg_ssp, 0);
       tmp = gen_rtx_SET (reg_adj,
  gen_rtx_LSHIFTRT (Pmode, negate_rtx (Pmode, reg_adj),
-   GEN_INT ((Pmode == SImode)
+   GEN_INT ((word_mode == SImode)
     ? 2
     : 3)));

be

+      reg_adj = gen_rtx_SUBREG (ptr_mode, reg_ssp, 0);
       tmp = gen_rtx_SET (reg_adj,
  gen_rtx_LSHIFTRT (ptr_mode, negate_rtx (ptr_mode, reg_adj),
-   GEN_INT ((Pmode == SImode)
+   GEN_INT ((word_mode == SImode)
     ? 2
     : 3)));

Pmode == word_mode for -maddress-mode=long.

+++ b/gcc/testsuite/gcc.target/i386/cet-sjlj-6.c
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fcf-protection -mcet -mx32" } */
+/* { dg-final { scan-assembler-times "endbr64" 2 } } */
+/* { dg-final { scan-assembler-times "movq\t.*buf\\+12" 1 } } */
+/* { dg-final { scan-assembler-times "subq\tbuf\\+12" 1 } } */
+/* { dg-final { scan-assembler-times "rdsspq" 2 } } */
+/* { dg-final { scan-assembler-times "incsspq" 2 } } */

Please add a test for

       tmp = gen_rtx_SET (reg_adj,
  gen_rtx_LSHIFTRT (Pmode, negate_rtx (Pmode, reg_adj),
-   GEN_INT ((Pmode == SImode)
+   GEN_INT ((word_mode == SImode)
     ? 2
     : 3)));


-- 
H.J.