baremetal: implement C assert

README.adoc

@@ -14012,7 +14012,14 @@ lkmc_exit_status_(\d+)
 and then exit with the given regular expression, e.g.:
 
 ....
-./run --arch aarch64 baremetal
+./run --arch aarch64 baremetal/return2.c
+echo $?
+....
+
+should output:
+
+....
+2
 ....
 
 This magic output string is notably generated by:
@@ -14028,6 +14035,7 @@ So setup this `on_exit` automatically from all our <<baremetal-bootloaders>>, so
 +
 The following examples end up testing that our setup is working:
 +
+* link:baremetal/assert_fail.c[]
 * link:baremetal/lkmc_assert_fail.c[]
 * link:baremetal/return1.c[]
 * link:baremetal/return2.c[]
@@ -14038,6 +14046,30 @@ The following examples end up testing that our setup is working:
 
 Beware that on Linux kernel simulations, you cannot even echo that string from userland, since userland stdout shows up on the serial.
 
+====== baremetal assert
+
+TODO: implement enough syscalls for it, so we can get the error line:
+
+....
+cd baremetal
+ln -s ../lkmc/assert_fail.c
+cd ..
+./build --arch aarch64
+....
+
+fails with:
+
+....
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/install/aarch64/lib/gcc/aarch64-unknown-elf/8.1.0/../../../../aarch64-unknown-elf/lib/libg.a(lib_a-signalr.o): In function `_kill_r':
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/build/aarch64-unknown-elf/src/newlib/newlib/libc/reent/signalr.c:53: undefined reference to `_kill'
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/build/aarch64-unknown-elf/src/newlib/newlib/libc/reent/signalr.c:53:(.text+0x20): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `_kill'
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/install/aarch64/lib/gcc/aarch64-unknown-elf/8.1.0/../../../../aarch64-unknown-elf/lib/libg.a(lib_a-signalr.o): In function `_getpid_r':
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/build/aarch64-unknown-elf/src/newlib/newlib/libc/reent/signalr.c:83: undefined reference to `_getpid'
+/path/to/linux-kernel-module-cheat/out/crosstool-ng/build/default/build/aarch64-unknown-elf/src/newlib/newlib/libc/reent/signalr.c:83:(.text+0x44): relocation truncated to fit: R_AARCH64_JUMP26 against undefined symbol `_getpid'
+....
+
+at 406ee82cf33a6e3df0067b219b0414c59d7018b3 + 1.
+
 ==== Non-automated tests
 
 ===== Test GDB Linux kernel

baremetal/assert_fail.c

@@ -0,0 +1 @@
+../lkmc/assert_fail.c

baremetal/lib/syscalls.c

@@ -13,13 +13,55 @@ enum {
 
 int _close(int file) { return -1; }
 
+void _exit(int status) {
+#if defined(GEM5)
+    LKMC_M5OPS_EXIT;
+#else
+#if defined(__arm__)
+    __asm__ __volatile__ (
+        "mov r0, #0x18\n"
+        "ldr r1, =#0x20026\n"
+        "svc 0x00123456\n"
+        :
+        :
+        : "r0", "r1"
+    );
+#elif defined(__aarch64__)
+    /* TODO actually use the exit value here, just for fun. */
+    __asm__ __volatile__ (
+        "mov x1, #0x26\n" \
+        "movk x1, #2, lsl #16\n" \
+        "str x1, [sp,#0]\n" \
+        "mov x0, #0\n" \
+        "str x0, [sp,#8]\n" \
+        "mov x1, sp\n" \
+        "mov w0, #0x18\n" \
+        "hlt 0xf000\n"
+        :
+        :
+        : "x0", "x1"
+    );
+#endif
+#endif
+}
+
 int _fstat(int file, struct stat *st) {
     st->st_mode = S_IFCHR;
     return 0;
 }
 
+/* Required by assert. */
+int _getpid(void) { return 0; }
+
+/* Required by assert. */
+int _kill(pid_t pid, int sig) {
+    exit(128 + sig);
+}
+
 int _isatty(int file) { return 1; }
+
 int _lseek(int file, int ptr, int dir) { return 0; }
+
 int _open(const char *name, int flags, int mode) { return -1; }
 
 int _read(int file, char *ptr, int len) {
@@ -61,35 +103,3 @@ int _write(int file, char *ptr, int len) {
     }
     return len;
 }
-
-void _exit(int status) {
-#if defined(GEM5)
-    LKMC_M5OPS_EXIT;
-#else
-#if defined(__arm__)
-    __asm__ __volatile__ (
-        "mov r0, #0x18\n"
-        "ldr r1, =#0x20026\n"
-        "svc 0x00123456\n"
-        :
-        :
-        : "r0", "r1"
-    );
-#elif defined(__aarch64__)
-    /* TODO actually use the exit value here, just for fun. */
-    __asm__ __volatile__ (
-        "mov x1, #0x26\n" \
-        "movk x1, #2, lsl #16\n" \
-        "str x1, [sp,#0]\n" \
-        "mov x0, #0\n" \
-        "str x0, [sp,#8]\n" \
-        "mov x1, sp\n" \
-        "mov w0, #0x18\n" \
-        "hlt 0xf000\n"
-        :
-        :
-        : "x0", "x1"
-    );
-#endif
-#endif
-}

baremetal/lkmc_assert_fail.c

@@ -1 +1 @@
-../lkmc/assert_fail.c
+../lkmc/lkmc_assert_fail.c

lkmc/assert_fail.c

@@ -1,5 +1,18 @@
-#include <lkmc.h>
+/* Let's see what happens when an assert fails.
+ *
+ * Outcome on Ubuntu 19.04 shows the failure line:
+ *
+ *     assert_fail.out: /path/to/linux-kernel-module-cheat/userland/c/assert_fail.c:15: main: Assertion `0' failed.
+ *
+ * and exit status 134 == 128 + 6, which corresponds to SIGABORT (6).
+ */
+
+#include <assert.h>
+#include <stdlib.h>
+#include <stdio.h>
 
 int main(void) {
-    lkmc_assert_fail();
+    assert(0);
+    puts("here");
+    return EXIT_SUCCESS;
 }

lkmc/lkmc_assert_fail.c

@@ -0,0 +1,5 @@
+#include <lkmc.h>
+
+int main(void) {
+    lkmc_assert_fail();
+}

path_properties.py

@@ -242,6 +242,7 @@ path_properties_tuples = (
                         )
                     }
                 ),
+                'assert_fail.c': {'exit_status': 134},
                 'lkmc_assert_fail.c': {'exit_status': 1},
                 'exit1.c': {'exit_status': 1},
                 'infinite_loop.c': {'more_than_1s': True},
@@ -344,6 +345,7 @@ path_properties_tuples = (
                 'c': (
                     {},
                     {
+                        'assert_fail.c': {'receives_signal': True},
                         'false.c': {'exit_status': 1},
                         'getchar.c': {'interactive': True},
                         'infinite_loop.c': {'more_than_1s': True},

userland/c/assert_fail.c

@@ -0,0 +1 @@
+../../lkmc/assert_fail.c

userland/lkmc/assert_fail.c

@@ -1 +1 @@
-../../lkmc/assert_fail.c
+../../lkmc/lkmc_assert_fail.c