> -----Original Message-----
> From: Richard Earnshaw <richard.earns...@arm.com>
> Sent: Monday, October 11, 2021 2:58 PM
> To: Tejas Belagod <tejas.bela...@arm.com>; gcc-patches@gcc.gnu.org
> Subject: Re: [Patch 4/7, Arm. GCC] Implement target feature macros for
> PACBTI.
>
> On 08/10/2021 13:18, Tejas Belagod via Gcc-patches wrote:
> > Hi,
> >
> > This patch implements target feature macros when PACBTI is enabled
> > through the -march option or -mbranch-protection.
> >
> > Tested on arm-none-eabi. OK for trunk?
> >
> > 2021-10-04 Tejas Belagod <tbela...@arm.com>
> >
> > gcc/ChangeLog:
> >
> > * config/arm/arm-c.c (arm_cpu_builtins): Define
> > __ARM_FEATURE_BTI_DEFAULT and
> __ARM_FEATURE_PAC_DEFAULT.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * gcc.target/arm/acle/pacbti-m-predef-2.c: New test.
> > * gcc.target/arm/acle/pacbti-m-predef-4.c: New test.
> > * gcc.target/arm/acle/pacbti-m-predef-5.c: New test.
> >
>
> I presume the specification for this is ACLE - please say so rather than
> making
> me guess.
>
Yes, sorry, very poor description on my part. Now fixed - please see patch
description below for links to specific ACLE sections.
>
> + cpp_undef (pfile, "__ARM_FEATURE_BTI_DEFAULT");
> + cpp_undef (pfile, "__ARM_FEATURE_PAC_DEFAULT");
> + if (TARGET_HAVE_PACBTI)
> + {
> + builtin_define_with_int_value ("__ARM_FEATURE_BTI_DEFAULT",
> + arm_enable_pacbti & 0x1);
>
> My reading of the ACLE specification would suggest this shouldn't be
> defined if it would have a value of 0, but that's not what this code
> does. I think it would be better to move this outside the
> TARGET_HAVE_PACBTI and use the def_or_undef approach.
>
> + builtin_define_with_int_value ("__ARM_FEATURE_PAC_DEFAULT",
> + arm_enable_pacbti >> 1);
>
> This one is less clear, could the value ever be zero? I guess exactly
> one of a-key and b-key must be defined and each has a separate bit.
>
Now fixed according to what the arch specifies. For the M-profile, there's only
one key which means when -mbranch-protection is invoked, bit 0 is always 1.
> + }
> +
> +
>
> Not more than one blank line at the end of a block.
>
>
> diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
> b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
>
>
> Given what I've said above, I think you need to also test that
> __ARM_FEATURE_BTI_DEFAULT is defined before testing the value (and
> emitting #error if it isn't).
>
Fixed.
This patch implements target feature macros when PACBTI is
enabled through the -march option or -mbranch-protection.
The target feature macros __ARM_FEATURE_PAC_DEFAULT and
__ARM_FEATURE_BTI_DEFAULT are specified in ARM ACLE
(https://developer.arm.com/documentation/101028/0012/5--Feature-test-macros?lang=en)
__ARM_FEATURE_PAUTH and __ARM_FEATURE_BTI are specified in the pull-request
(https://github.com/ARM-software/acle/pull/55).
2021-10-25 Tejas Belagod <tbela...@arm.com>
gcc/ChangeLog:
* config/arm/arm-c.c (arm_cpu_builtins): Define
__ARM_FEATURE_BTI_DEFAULT, __ARM_FEATURE_PAC_DEFAULT,
__ARM_FEATURE_PAUTH and __ARM_FEATURE_BTI.
gcc/testsuite/ChangeLog:
* gcc.target/arm/acle/pacbti-m-predef-2.c: New test.
* gcc.target/arm/acle/pacbti-m-predef-4.c: New test.
* gcc.target/arm/acle/pacbti-m-predef-5.c: New test.
Tested the following configurations, OK for trunk?
-mthumb/-march=armv8.1-m.main+pacbti/-mfloat-abi=soft
-marm/-march=armv7-a/-mfpu=vfpv3-d16/-mfloat-abi=softfp
mcmodel=small and tiny
aarch64-none-linux-gnu native test and bootstrap
Thanks,
Tejas.
diff --git a/gcc/config/arm/arm-c.c b/gcc/config/arm/arm-c.c
index
cc7901bca8dc9c5c27ed6afc5bc26afd42689e6d..98d47ad4cc6e88aa7401429a809c555c5aadc15f
100644
--- a/gcc/config/arm/arm-c.c
+++ b/gcc/config/arm/arm-c.c
@@ -193,6 +193,24 @@ arm_cpu_builtins (struct cpp_reader* pfile)
def_or_undef_macro (pfile, "__ARM_FEATURE_COMPLEX", TARGET_COMPLEX);
def_or_undef_macro (pfile, "__ARM_32BIT_STATE", TARGET_32BIT);
+ def_or_undef_macro (pfile, "__ARM_FEATURE_PAUTH", TARGET_HAVE_PACBTI);
+ def_or_undef_macro (pfile, "__ARM_FEATURE_BTI", TARGET_HAVE_PACBTI);
+ def_or_undef_macro (pfile, "__ARM_FEATURE_BTI_DEFAULT",
+ aarch_enable_bti == 1);
+
+ cpp_undef (pfile, "__ARM_FEATURE_PAC_DEFAULT");
+ if (aarch_ra_sign_scope != AARCH_FUNCTION_NONE)
+ {
+ unsigned int pac = 1;
+
+ gcc_assert (aarch_ra_sign_key == AARCH_KEY_A);
+
+ if (aarch_ra_sign_scope == AARCH_FUNCTION_ALL)
+ pac |= 0x4;
+
+ builtin_define_with_int_value ("__ARM_FEATURE_PAC_DEFAULT", pac);
+ }
+
cpp_undef (pfile, "__ARM_FEATURE_MVE");
if (TARGET_HAVE_MVE && TARGET_HAVE_MVE_FLOAT)
{
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
new file mode 100644
index
0000000000000000000000000000000000000000..4394fd147d7bf468238bd66a24b79bd1338d33aa
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-2.c
@@ -0,0 +1,24 @@
+
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-additional-options " -mbranch-protection=bti+pac-ret+leaf" } */
+
+#if !defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
+
+int
+main()
+{
+ if (__ARM_FEATURE_BTI_DEFAULT != 1)
+ __builtin_abort ();
+
+ if (__ARM_FEATURE_PAC_DEFAULT != 5)
+ __builtin_abort ();
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
new file mode 100644
index
0000000000000000000000000000000000000000..90f0c724b9efe38d3c3a1345d49a9615b853207e
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-4.c
@@ -0,0 +1,21 @@
+
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-additional-options " -mbranch-protection=pac-ret" } */
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be undefined."
+#endif
+
+int
+main()
+{
+ if (__ARM_FEATURE_PAC_DEFAULT != 1)
+ __builtin_abort ();
+
+ return 0;
+}
diff --git a/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
new file mode 100644
index
0000000000000000000000000000000000000000..c865809b8b01db8f8c021501e7d3317b0b8bb0ed
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/acle/pacbti-m-predef-5.c
@@ -0,0 +1,24 @@
+
+/* { dg-do run } */
+/* { dg-require-effective-target arm_pacbti_hw } */
+/* { dg-additional-options " -mbranch-protection=bti+pac-ret" } */
+
+#if !defined (__ARM_FEATURE_BTI_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_BTI_DEFAULT should be defined."
+#endif
+
+#if !defined (__ARM_FEATURE_PAC_DEFAULT)
+#error "Feature test macro __ARM_FEATURE_PAC_DEFAULT should be defined."
+#endif
+
+int
+main()
+{
+ if (__ARM_FEATURE_BTI_DEFAULT != 1)
+ __builtin_abort ();
+
+ if (__ARM_FEATURE_PAC_DEFAULT != 1)
+ __builtin_abort ();
+
+ return 0;
+}
