[ARM][CMSE] Add CMSE header & builtins

[javed.absar]

Summary

This is patch C2 as mentioned in RFC http://lists.llvm.org/pipermail/cfe-dev/2019-March/061834.html

This adds cmse builtin functions, and introduces arm_cmse.h header which has useful macros, functions and data types for end-users of cmse.

[sigvartmh]

This comment was removed by sigvartmh.

[javed.absar]

In D62394#1672551, @sigvartmh wrote:

Maybe I'm doing something wrong tried to apply these patches but when trying to build code which uses cmse I get

Cannot select: intrinsic %llvm.arm.cmse.tt
fatal error: error in backend: Cannot select: intrinsic %llvm.arm.cmse.tt
clang-10: error: clang frontend command failed with exit code 70 (use -v to see invocation)

Built llvm with clang,compiler-rt,lld from master.

Did you try to build and run lit tests successfully with this patch before trying your own tests?

[sigvartmh]

In D62394#1672570, @javed.absar wrote:

In D62394#1672551, @sigvartmh wrote:

Maybe I'm doing something wrong tried to apply these patches but when trying to build code which uses cmse I get

Cannot select: intrinsic %llvm.arm.cmse.tt
fatal error: error in backend: Cannot select: intrinsic %llvm.arm.cmse.tt
clang-10: error: clang frontend command failed with exit code 70 (use -v to see invocation)

Built llvm with clang,compiler-rt,lld from master.

Did you try to build and run lit tests successfully with this patch before trying your own tests?

Unfortunately I did not will try to run the test first. I assumed that this patch was working, is it?

[dmgreen]

I'm afraid the upstreaming of CMSE has stalled, and this is not all that would be needed to get it working. This adds some header files and clang builtins, the selection of them in the backend isn't yet present, hence the error you are seeing. There are more patches to follow around lowering intrinsics and clearing registers correctly.

[sigvartmh]

Not used to phabricator tried to remove my request for change. So no one is working on upstreaming CMSE to LLVM now?

[pbarrio]

Hi, CMSE upstreaming is indeed one of our priorities. So yes, we are very interested in your feedback. And no, CMSE upstreaming is not abandoned, just going a bit slow ATM :( but any help reviewing is much appreciated! :)

@chill would it make sense to start upstream other self-contained pieces of codegen before this patch?

[chill]

I hope I will be able to pick this up in the following weeks and land patches a couple of weeks later. Sorry for the delay, but priorities shift all the time ;)

include/clang/Basic/BuiltinsARM.def

 BUILTIN(__builtin_arm_crc32cb, "UiUiUc", "nc")
 BUILTIN(__builtin_arm_crc32h, "UiUiUs", "nc")
 BUILTIN(__builtin_arm_crc32ch, "UiUiUs", "nc")
 BUILTIN(__builtin_arm_crc32w, "UiUiUi", "nc")
 BUILTIN(__builtin_arm_crc32cw, "UiUiUi", "nc")
 BUILTIN(__builtin_arm_crc32d, "UiUiLLUi", "nc")
 BUILTIN(__builtin_arm_crc32cd, "UiUiLLUi", "nc")
 
+// ARMv8-M Security Extensions a.k.a CMSE
+BUILTIN(__builtin_arm_cmse_TT, "Uiv*", "n")
+BUILTIN(__builtin_arm_cmse_TTT, "Uiv*", "n")
+BUILTIN(__builtin_arm_cmse_TTA, "Uiv*", "n")
+BUILTIN(__builtin_arm_cmse_TTAT, "Uiv*", "n")
+
 // HINT
 BUILTIN(__builtin_arm_nop, "v", "")
 BUILTIN(__builtin_arm_yield, "v", "")
 BUILTIN(__builtin_arm_wfe, "v", "")
 BUILTIN(__builtin_arm_wfi, "v", "")
 BUILTIN(__builtin_arm_sev, "v", "")
 BUILTIN(__builtin_arm_sevl, "v", "")
 BUILTIN(__builtin_arm_dbg, "vUi", "")

lib/Headers/CMakeLists.txt

 set(files
   adxintrin.h
   altivec.h
   ammintrin.h
   arm_acle.h
+  arm_cmse.h
   armintr.h
   arm64intr.h
   avx2intrin.h
   avx512bf16intrin.h
   avx512bwintrin.h
   avx512bitalgintrin.h
   avx512vlbitalgintrin.h
   avx512cdintrin.h

lib/Headers/arm_cmse.h

+//===---- arm_cmse.h - Arm CMSE support -----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+#ifndef __ARM_CMSE_H
+#define __ARM_CMSE_H
+
+#if (__ARM_FEATURE_CMSE & 0x1)
+#include <stdint.h>
+#include <stddef.h>
+
+#define __CMSE_SECURE_MODE (__ARM_FEATURE_CMSE & 0x2)
+#define CMSE_MPU_READWRITE 1              /*checks if readwrite_ok field is set*/
+#define CMSE_AU_NONSECURE  2              /*checks if permissions have secure field unset*/
+#define CMSE_MPU_UNPRIV    4              /*sets T flag on TT insrtuction*/
+#define CMSE_MPU_READ      8              /*checks if read_ok field is set*/
+#define CMSE_MPU_NONSECURE 16             /*sets A flag, checks if secure field unset*/
+#define CMSE_NONSECURE     (CMSE_AU_NONSECURE | CMSE_MPU_NONSECURE)
+#define cmse_check_pointed_object(p, f) (cmse_check_address_range(p, sizeof(*p), f))
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+typedef union {
+  struct cmse_address_info {
+#ifdef __ARM_BIG_ENDIAN
+      /* __ARM_BIG_ENDIAN */
+#if (__CMSE_SECURE_MODE)
+    unsigned idau_region:8;            /*bit 31-24*/
+    unsigned idau_region_valid:1;      /*bit 23-23*/
+    unsigned secure:1;                 /*bit 22-22*/
+    unsigned nonsecure_readwrite_ok:1; /*bit 21-21*/
+    unsigned nonsecure_read_ok:1;      /*bit 20-20*/
+#else
+    unsigned :12;                      /*bit 31-20*/
+#endif
+    unsigned readwrite_ok:1;           /*bit 19-19*/
+    unsigned read_ok:1;                /*bit 18-18*/
+#if (__CMSE_SECURE_MODE)
+    unsigned sau_region_valid:1;       /*bit 17-17*/
+#else
+    unsigned :1;                       /*bit 17-17*/
+#endif
+    unsigned mpu_region_valid:1;       /*bit 16-16*/
+#if (__CMSE_SECURE_MODE)
+    unsigned sau_region:8;             /*bit 15-08*/
+#else
+    unsigned :8;                       /*bit 15-08*/
+#endif
+    unsigned mpu_region:8;             /*bit 07-00*/
+
+#else /* __ARM_LITTLE_ENDIAN */
+    unsigned mpu_region:8;             /*bit 31-24*/
+#if (__CMSE_SECURE_MODE)
+    unsigned sau_region:8;             /*bit 23-16*/
+#else
+    unsigned :8;                       /*bit 23-16*/
+#endif
+    unsigned mpu_region_valid:1;       /*bit 15-15*/
+#if (__CMSE_SECURE_MODE)
+    unsigned sau_region_valid:1;       /*bit 14-14*/
+#else
+    unsigned :1;                       /*bit 14-14*/
+#endif
+    unsigned read_ok:1;                /*bit 13-13*/
+    unsigned readwrite_ok:1;           /*bit 12-12*/
+#if (__CMSE_SECURE_MODE)
+    unsigned nonsecure_read_ok:1;      /*bit 11-11*/
+    unsigned nonsecure_readwrite_ok:1; /*bit 10-10*/
+    unsigned secure:1;                 /*bit 09-09*/
+    unsigned idau_region_valid:1;      /*bit 08-08*/
+    unsigned idau_region:8;            /*bit 07-00*/
+#else
+    unsigned :12;                      /*bit 11-00*/
+#endif
+#endif /*__ARM_LITTLE_ENDIAN */
+  } flags;
+  unsigned value;
+} cmse_address_info_t;
+
+
+static cmse_address_info_t  __attribute__((__always_inline__, __nodebug__)) cmse_TT(void *p) {
+  cmse_address_info_t u;
+  u.value = __builtin_arm_cmse_TT(p);
+  return u;
+}
+static cmse_address_info_t  __attribute__((__always_inline__, __nodebug__)) cmse_TTT(void *p) {
+  cmse_address_info_t u;
+  u.value = __builtin_arm_cmse_TTT(p);
+  return u;
+}
+
+#if __CMSE_SECURE_MODE
+static cmse_address_info_t  __attribute__((__always_inline__, __nodebug__)) cmse_TTA(void *p) {
+  cmse_address_info_t u;
+  u.value = __builtin_arm_cmse_TTA(p);
+  return u;
+}
+static cmse_address_info_t  __attribute__((__always_inline__, __nodebug__)) cmse_TTAT(void *p) {
+  cmse_address_info_t u;
+  u.value = __builtin_arm_cmse_TTAT(p);
+  return u;
+}
+#endif
+
+#define cmse_TT_fptr(p) (cmse_TT((void*)p))
+#define cmse_TTT_fptr(p) (cmse_TTT((void*)p))
+
+#if __CMSE_SECURE_MODE
+#define cmse_TTA_fptr(p) (cmse_TTA((void*)p))
+#define cmse_TTAT_fptr(p) (cmse_TTAT((void*)p))
+#endif
+
+static void* __attribute__((__always_inline__)) cmse_check_address_range(void *p, size_t s, int flags){
+  cmse_address_info_t permb, perme;
+  char *pb = (char *)p;
+  char *pe = pb + s -1;
+
+  if ((uintptr_t)pe < (uintptr_t)pb) return NULL; // wrap around check
+
+  // execute the right variant of the TT instructions
+  const int singleCheck = (((uintptr_t) pb ^ (uintptr_t) pe) < 0x20u);
+
+  switch (flags & (CMSE_MPU_UNPRIV | CMSE_MPU_NONSECURE)) {
+    case 0:
+      permb = cmse_TT(pb);
+      perme = singleCheck ? permb : cmse_TT(pe);
+      break;
+    case CMSE_MPU_UNPRIV:
+      permb = cmse_TTT(pb);
+      perme = singleCheck ? permb : cmse_TTT(pe);
+      break;
+#if __CMSE_SECURE_MODE
+    case CMSE_MPU_NONSECURE:
+      permb = cmse_TTA(pb);
+      perme = singleCheck ? permb : cmse_TTA(pe);
+      break;
+    case CMSE_MPU_UNPRIV | CMSE_MPU_NONSECURE:
+      permb = cmse_TTAT(pb);
+      perme = singleCheck ? permb : cmse_TTAT(pe);
+      break;
+#endif
+    // if CMSE_NONSECURE is specified w/o __CMSE_SECURE_MODE
+    default:
+      return NULL;
+  }
+
+  // check that the range does not cross MPU, SAU, or IDAU region boundaries
+  if (permb.value != perme.value) return NULL;
+#if ! (__CMSE_SECURE_MODE)
+    // CMSE_AU_NONSECURE is only supported when __ARM_FEATURE_CMSE & 0x2
+  if (flags & CMSE_AU_NONSECURE) return NULL;
+#endif
+
+  // check the permission on the range
+  switch (flags & ~(CMSE_MPU_UNPRIV|CMSE_MPU_NONSECURE)) {
+#if (__CMSE_SECURE_MODE)
+    case CMSE_MPU_READ|CMSE_MPU_READWRITE|CMSE_AU_NONSECURE:
+    case CMSE_MPU_READWRITE|CMSE_AU_NONSECURE:
+      return permb.flags.nonsecure_readwrite_ok ? p : NULL;
+
+    case CMSE_MPU_READ|CMSE_AU_NONSECURE:
+      return permb.flags.nonsecure_read_ok ? p : NULL;
+
+    case CMSE_AU_NONSECURE:
+      return permb.flags.secure ? NULL : p;
+#endif
+    case CMSE_MPU_READ|CMSE_MPU_READWRITE:
+    case               CMSE_MPU_READWRITE:
+      return permb.flags.readwrite_ok ? p : NULL;
+
+    case CMSE_MPU_READ:
+      return permb.flags.read_ok ? p : NULL;
+
+   default:
+     return NULL;
+  }
+}
+
+#if __CMSE_SECURE_MODE
+static int __attribute__((__always_inline__, __nodebug__)) cmse_nonsecure_caller(void) {
+  return !((intptr_t)__builtin_return_address(0) & 1);
+}
+
+#define cmse_nsfptr_create(p)   ((__typeof__(p)) ((intptr_t) p & ~1))
+#define cmse_is_nsfptr(p)       (!((intptr_t) p & 1))
+#endif // __CMSE_SECURE_MODE
+
+void __attribute__((__noreturn__)) cmse_abort(void);
+#if defined(__cplusplus)
+}
+#endif
+#endif /* (__ARM_FEATURE_CMSE & 0x1) */
+#endif /* __ARM_CMSE_H */

test/CodeGen/arm-cmse-nonsecure.c

+// RUN: %clang -fvisibility=default -mlittle-endian -Xclang -ffreestanding -target thumbv8m.base-linux-gnueabihf  -emit-llvm -S -o - %s | FileCheck %s
+// RUN-: %clang -fvisibility=default -mbig-endian    -Xclang -ffreestanding -target thumbv8m.base-linux-gnueabihf  -emit-llvm -S -o - %s | FileCheck %s
+
+#include <arm_cmse.h>
+
+unsigned test_cmse_primitives(void *p) {
+// CHECK: define {{.*}} i32 @test_cmse_primitives
+  cmse_address_info_t tt_val, ttt_val;
+  unsigned sum;
+
+  tt_val = cmse_TT(p);
+  ttt_val = cmse_TTT(p);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK-NOT: llvm.arm.cmse.tta
+// CHECK-NOT: llvm.arm.cmse.ttat
+
+  sum = tt_val.value;
+  sum += ttt_val.value;
+
+  sum += tt_val.flags.mpu_region;
+  sum += tt_val.flags.mpu_region_valid;
+  sum += tt_val.flags.read_ok;
+  sum += tt_val.flags.readwrite_ok;
+
+  return sum;
+}
+
+void *test_address_range(void *p) {
+// CHECK: define {{.*}} i8* @test_address_range
+  return cmse_check_address_range(p, 128, CMSE_MPU_UNPRIV
+                                        | CMSE_MPU_READWRITE
+                                        | CMSE_MPU_READ);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK-NOT: llvm.arm.cmse.tta
+// CHECK-NOT: llvm.arm.cmse.ttat
+}
+
+typedef struct {
+    int x, y, z;
+} Point;
+
+void *test_pointed_object(void *p) {
+// CHECK: define {{.*}} i8* @test_pointed_object
+  Point *pt = (Point *)p;
+  cmse_check_pointed_object(pt, CMSE_MPU_READ);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK-NOT: call i32 @llvm.arm.cmse.tta
+// CHECK-NOT: call i32 @llvm.arm.cmse.ttat
+}

test/CodeGen/arm-cmse-secure.c

+// RUN: %clang -fvisibility=default -mlittle-endian -mcmse -Xclang -ffreestanding -target thumbv8m.base-linux-gnueabihf -emit-llvm -S -o - %s | FileCheck %s
+// RUN: %clang -fvisibility=default -mbig-endian    -mcmse -Xclang -ffreestanding -target thumbv8m.base-linux-gnueabihf -emit-llvm -S -o - %s | FileCheck %s
+
+#include <arm_cmse.h>
+
+unsigned test_cmse_primitives(void *p) {
+// CHECK: define {{.*}} i32 @test_cmse_primitives
+  cmse_address_info_t tt_val, ttt_val;
+  cmse_address_info_t tta_val, ttat_val;
+  unsigned sum;
+
+  tt_val = cmse_TT(p);
+  ttt_val = cmse_TTT(p);
+  tta_val = cmse_TTA(p);
+  ttat_val = cmse_TTAT(p);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK: call i32 @llvm.arm.cmse.tta
+// CHECK: call i32 @llvm.arm.cmse.ttat
+
+  sum = tt_val.value;
+  sum += ttt_val.value;
+  sum += tta_val.value;
+  sum += ttat_val.value;
+
+  sum += tt_val.flags.mpu_region;
+  sum += tt_val.flags.sau_region;
+  sum += tt_val.flags.mpu_region_valid;
+  sum += tt_val.flags.sau_region_valid;
+  sum += tt_val.flags.read_ok;
+  sum += tt_val.flags.readwrite_ok;
+  sum += tt_val.flags.nonsecure_read_ok;
+  sum += tt_val.flags.nonsecure_readwrite_ok;
+  sum += tt_val.flags.secure;
+  sum += tt_val.flags.idau_region_valid;
+  sum += tt_val.flags.idau_region;
+
+  return sum;
+}
+
+void *test_address_range(void *p) {
+// CHECK: define {{.*}} i8* @test_address_range
+  return cmse_check_address_range(p, 128, CMSE_MPU_UNPRIV
+                                        | CMSE_MPU_NONSECURE
+                                        | CMSE_MPU_READWRITE);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK: call i32 @llvm.arm.cmse.tta
+// CHECK: call i32 @llvm.arm.cmse.ttat
+}
+
+typedef struct {
+  int x, y, z;
+} Point;
+
+void *test_pointed_object(void *p) {
+// CHECK: define {{.*}} i8* @test_pointed_object
+  Point *pt = (Point *)p;
+  cmse_check_pointed_object(pt, CMSE_NONSECURE
+                              | CMSE_MPU_READ
+                              | CMSE_AU_NONSECURE);
+// CHECK: call i32 @llvm.arm.cmse.tt
+// CHECK: call i32 @llvm.arm.cmse.ttt
+// CHECK: call i32 @llvm.arm.cmse.tta
+// CHECK: call i32 @llvm.arm.cmse.ttat
+}

test/CodeGen/arm-cmse.c

+// RUN: %clang_cc1 -triple thumbv8m.base-none-eabi -O1 -emit-llvm %s -o - | FileCheck %s
+int test_cmse_TT(void *p){
+  return __builtin_arm_cmse_TT(p);
+  // CHECK: call i32 @llvm.arm.cmse.tt(i8* %{{.*}})
+}
+
+int test_cmse_TTT(void *p){
+  return __builtin_arm_cmse_TTT(p);
+  // CHECK: call i32 @llvm.arm.cmse.ttt(i8* %{{.*}})
+}
+
+int test_cmse_TTA(void *p){
+  return __builtin_arm_cmse_TTA(p);
+  // CHECK: call i32 @llvm.arm.cmse.tta(i8* %{{.*}})
+}
+
+int test_cmse_TTAT(void *p){
+  return __builtin_arm_cmse_TTAT(p);
+  // CHECK: call i32 @llvm.arm.cmse.ttat(i8* %{{.*}})
+}

test/Headers/arm-cmse-header-ns.c

+// RUN: %clang_cc1 -triple thumbv8m.base-linux-gnueabihf  -fsyntax-only -ffreestanding %s 2>&1 | FileCheck --check-prefix=CHECK-c %s
+// RUN: not %clang_cc1 -triple thumbv8m.base-linux-gnueabihf  -fsyntax-only -ffreestanding -x c++ %s 2>&1 | FileCheck --check-prefix=CHECK-cpp %s
+
+#include <arm_cmse.h>
+
+typedef void (*callback_t)(void);
+
+void func(callback_t fptr, void *p)
+{
+  cmse_TT(p);
+  cmse_TTT(p);
+  cmse_TT_fptr(fptr);
+  cmse_TTT_fptr(fptr);
+
+  cmse_TTA(p);
+  cmse_TTAT(p);
+  cmse_TTA_fptr(fptr);
+  cmse_TTAT_fptr(fptr);
+// CHECK-c: warning: implicit declaration of function 'cmse_TTA'
+// CHECK-c: warning: implicit declaration of function 'cmse_TTAT'
+// CHECK-c: warning: implicit declaration of function 'cmse_TTA_fptr'
+// CHECK-c: warning: implicit declaration of function 'cmse_TTAT_fptr'
+// CHECK-cpp: error: use of undeclared identifier 'cmse_TTA'
+// CHECK-cpp: error: use of undeclared identifier 'cmse_TTAT'
+// CHECK-cpp: error: use of undeclared identifier 'cmse_TTA_fptr'
+// CHECK-cpp: error: use of undeclared identifier 'cmse_TTAT_fptr'
+}

test/Headers/arm-cmse-header.c

+// RUN: %clang_cc1 -triple thumbv8m.base-linux-gnueabihf  -fsyntax-only -ffreestanding %s -verify -mcmse
+// RUN: %clang_cc1 -triple thumbv8m.base-linux-gnueabihf  -fsyntax-only -ffreestanding -x c++ %s -verify -mcmse
+// expected-no-diagnostics
+
+#include <arm_cmse.h>
+
+typedef void (*callback_t)(void);
+
+void func(callback_t fptr, void *p)
+{
+  cmse_TT(p);
+  cmse_TTT(p);
+  cmse_TTA(p);
+  cmse_TTAT(p);
+
+  cmse_TT_fptr(fptr);
+  cmse_TTT_fptr(fptr);
+  cmse_TTA_fptr(fptr);
+  cmse_TTAT_fptr(fptr);
+}