Merge tag 'nolibc-20260814-for-7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc

Pull nolibc updates from Thomas Weißschuh:

 - New architecture: Alpha

 - New library functionality: readlink(), getcwd()

 - Various bugfixes and cleanups

* tag 'nolibc-20260814-for-7.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/nolibc/linux-nolibc:
  tools/nolibc: add support for Alpha
  tools/nolibc/powerpc: mark ctr and xer as clobbered by system call
  tools/nolibc: remove dead __ARCH_WANT_SYS_OLD_SELECT
  selftests/nolibc: add debug information
  tools/nolibc: mark arg1 operand in __nolibc_syscall0() as write-only
  selftests/nolibc: Add test for getcwd() and readlink()
  tools/nolibc: unistd: Add readlink()
  tools/nolibc: unistd: Add getcwd()

4 files changed, 62 insertions, 2 deletions

diff --git a/tools/testing/selftests/nolibc/Makefile.include b/tools/testing/selftests/nolibc/Makefile.include
index c30ca3a9ef14..ea520eac64a6 100644
--- a/tools/testing/selftests/nolibc/Makefile.include
+++ b/tools/testing/selftests/nolibc/Makefile.include
@@ -5,7 +5,7 @@ _CFLAGS_STACKPROTECTOR ?= $(call try-run, \
 	echo 'void foo(void) {}' | $(CC) -x c - -o - -S $(CLANG_CROSS_FLAGS) $(__CFLAGS_STACKPROTECTOR) | grep -q __stack_chk_guard, \
 	$(__CFLAGS_STACKPROTECTOR))
 _CFLAGS_SANITIZER ?= $(call cc-option,-fsanitize=undefined -fsanitize-trap=all)
-CFLAGS_NOLIBC_TEST  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 \
+CFLAGS_NOLIBC_TEST  ?= -Os -fno-ident -fno-asynchronous-unwind-tables -std=c89 -ggdb \
 		-W -Wall -Wextra -Wundef -Wwrite-strings \
 		$(call cc-option,-fno-stack-protector) $(call cc-option,-Wmissing-prototypes) \
 		$(_CFLAGS_STACKPROTECTOR) $(_CFLAGS_SANITIZER)
diff --git a/tools/testing/selftests/nolibc/Makefile.nolibc b/tools/testing/selftests/nolibc/Makefile.nolibc
index 06f881e2e90c..f70c8dfca018 100644
--- a/tools/testing/selftests/nolibc/Makefile.nolibc
+++ b/tools/testing/selftests/nolibc/Makefile.nolibc
@@ -112,6 +112,7 @@ EXTRACONFIG_armthumb  = -e CONFIG_NAMESPACES
 EXTRACONFIG_sparc32   = -e CONFIG_TMPFS
 EXTRACONFIG_m68k      = -e CONFIG_BLK_DEV_INITRD
 EXTRACONFIG_sh4       = -e CONFIG_BLK_DEV_INITRD -e CONFIG_CMDLINE_FROM_BOOTLOADER
+EXTRACONFIG_alpha     = -e CONFIG_BLK_DEV_INITRD
 EXTRACONFIG           = $(EXTRACONFIG_$(XARCH))
 
 # optional tests to run (default = all)
@@ -174,6 +175,7 @@ QEMU_ARGS_m68k       = -M virt -append "console=ttyGF0,115200 panic=-1 $(TEST:%=
 QEMU_ARGS_sh4        = -M r2d -serial file:/dev/stdout -append "console=ttySC1,115200 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS_openrisc   = -M virt -m 512M -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS_parisc32   = -M B160L -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
+QEMU_ARGS_alpha      = -M clipper -append "console=ttyS0 panic=-1 $(TEST:%=NOLIBC_TEST=%)"
 QEMU_ARGS            = -m 1G $(QEMU_ARGS_$(XARCH)) $(QEMU_ARGS_BIOS) $(QEMU_ARGS_EXTRA)
 
 # OUTPUT is only set when run from the main makefile, otherwise
diff --git a/tools/testing/selftests/nolibc/nolibc-test.c b/tools/testing/selftests/nolibc/nolibc-test.c
index c1c1ce43a047..ed860b0a15a1 100644
--- a/tools/testing/selftests/nolibc/nolibc-test.c
+++ b/tools/testing/selftests/nolibc/nolibc-test.c
@@ -756,6 +756,10 @@ int run_startup(int min, int max)
 	/* checking NULL for argv/argv0, environ and _auxv is not enough, let's compare with sbrk(0) or &end */
 	extern char end;
 	char *brk = sbrk(0) != (void *)-1 ? sbrk(0) : &end;
+#if defined(__alpha__)
+	/* the ordering above does not work on an alpha kernel due to STACK_TOP != TASK_SIZE */
+	brk = NULL;
+#endif
 	/* differ from nolibc, both glibc and musl have no global _auxv */
 	const unsigned long *test_auxv = (void *)-1;
 #ifdef NOLIBC
@@ -854,6 +858,58 @@ static int test_dirent(void)
 	return 0;
 }
 
+int test_getcwd(void)
+{
+	char cwd_syscall[PATH_MAX];
+	char cwd_proc[PATH_MAX];
+	ssize_t len;
+
+	/* Read where the link /proc/self/cwd points */
+	len = readlink("/proc/self/cwd", cwd_proc, sizeof(cwd_proc) - 1);
+	if (len <= 0)
+		return __LINE__;
+
+	/* Terminate the string from readlink() */
+	cwd_proc[len] = '\0';
+
+	/* Get the cwd via syscall */
+	if (getcwd(cwd_syscall, sizeof(cwd_syscall)) == NULL)
+		return __LINE__;
+
+	/* Fail if they aren't the same */
+	if (strcmp(cwd_proc, cwd_syscall) != 0)
+		return __LINE__;
+
+	/* Try getcwd() with NULL for the buffer,
+	 * should return NULL and an error in errno.
+	 * Other libc's allow this by allocating a buffer
+	 * internally.
+	 */
+	if (is_nolibc) {
+		errno = 0;
+		if (getcwd(NULL, 0) != NULL || !errno)
+			return __LINE__;
+	}
+
+	/* Try getcwd() with a buffer but make the size 0,
+	 * should return NULL and an error in errno.
+	 */
+	errno = 0;
+	if (getcwd(cwd_syscall, 0) != NULL || !errno)
+		return __LINE__;
+
+	/* Try getcwd() with a buffer but make the size 1,
+	 * should return NULL and an error in errno because
+	 * the string written to the buffer is terminated
+	 * so you need at least 2 bytes even for "/".
+	 */
+	errno = 0;
+	if (getcwd(cwd_syscall, 1) != NULL || !errno)
+		return __LINE__;
+
+	return 0;
+}
+
 int test_getrandom(void)
 {
 	uint64_t rng = 0;
@@ -1555,6 +1611,7 @@ int run_syscall(int min, int max)
 		CASE_TEST(clock_getres);      EXPECT_SYSZR(1, clock_getres(CLOCK_MONOTONIC, &ts)); break;
 		CASE_TEST(clock_gettime);     EXPECT_SYSZR(1, clock_gettime(CLOCK_MONOTONIC, &ts)); break;
 		CASE_TEST(clock_settime);     EXPECT_SYSER(1, clock_settime(CLOCK_MONOTONIC, &ts), -1, EINVAL); break;
+		CASE_TEST(getcwd);            EXPECT_SYSZR(proc, test_getcwd()); break;
 		CASE_TEST(getpid);            EXPECT_SYSNE(1, getpid(), -1); break;
 		CASE_TEST(getppid);           EXPECT_SYSNE(1, getppid(), -1); break;
 		CASE_TEST(gettid);            EXPECT_SYSNE(has_gettid, gettid(), -1); break;
diff --git a/tools/testing/selftests/nolibc/run-tests.sh b/tools/testing/selftests/nolibc/run-tests.sh
index 6460e25001de..dc0b1649c641 100755
--- a/tools/testing/selftests/nolibc/run-tests.sh
+++ b/tools/testing/selftests/nolibc/run-tests.sh
@@ -30,6 +30,7 @@ all_archs=(
 	m68k
 	sh4
 	parisc32
+	alpha
 )
 archs="${all_archs[@]}"
 
@@ -193,7 +194,7 @@ test_arch() {
 			exit 1
 	esac
 	printf '%-15s' "$arch:"
-	if [ "$arch" = "m68k" -o "$arch" = "sh4" -o "$arch" = "openrisc" -o "$arch" = "parisc32" ] && [ "$llvm" = "1" ]; then
+	if [ "$arch" = "m68k" -o "$arch" = "sh4" -o "$arch" = "openrisc" -o "$arch" = "parisc32" -o "$arch" = "alpha" ] && [ "$llvm" = "1" ]; then
 		echo "Unsupported configuration"
 		return
 	fi