Mostly cleanups and small things, notably:

- musl libc compatibility
  - vDSO installation fix
  - TLB sync race fix for recent SMP support
  - build fix for 32-bit with Clang 20/21
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Merge tag 'uml-for-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux

Pull uml updates from Johannes Berg:
 "Mostly cleanups and small things, notably:

   - musl libc compatibility

   - vDSO installation fix

   - TLB sync race fix for recent SMP support

   - build fix for 32-bit with Clang 20/21"

* tag 'uml-for-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/uml/linux:
  um: Disable GCOV_PROFILE_ALL on 32-bit UML with Clang 20/21
  um: drivers: call kernel_strrchr() explicitly in cow_user.c
  um: Replace strncpy() with strnlen()+memcpy_and_pad() in strncpy_chunk_from_user()
  x86/um: fix vDSO installation
  um: Remove CONFIG_FRAME_WARN from x86_64_defconfig
  um: Fix pte_read() and pte_exec() for kernel mappings
  um: Fix potential race condition in TLB sync
  um: time-travel: clean up kernel-doc warnings
  um: avoid struct sigcontext redefinition with musl
  um: fix address-of CMSG_DATA() rvalue in stub

arch/um/Kconfig

@@ -11,7 +11,9 @@ config UML
 	select ARCH_HAS_CACHE_LINE_SIZE
 	select ARCH_HAS_CPU_FINALIZE_INIT
 	select ARCH_HAS_FORTIFY_SOURCE
-	select ARCH_HAS_GCOV_PROFILE_ALL
+	# Clang 20 & 21 miscompute __builtin_object_size() under -fprofile-arcs
+	# on 32-bit, causing spurious compile-time errors in check_copy_size().
+	select ARCH_HAS_GCOV_PROFILE_ALL if !(!64BIT && CLANG_VERSION >= 200000 && CLANG_VERSION < 220100)
 	select ARCH_HAS_KCOV
 	select ARCH_HAS_STRNCPY_FROM_USER
 	select ARCH_HAS_STRNLEN_USER

arch/um/configs/x86_64_defconfig

@@ -60,5 +60,4 @@ CONFIG_PROC_KCORE=y
 CONFIG_TMPFS=y
 CONFIG_NLS=y
 CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y
-CONFIG_FRAME_WARN=1024
 CONFIG_DEBUG_KERNEL=y

arch/um/drivers/cow_user.c

@@ -15,6 +15,12 @@
 #include "cow.h"
 #include "cow_sys.h"
 
+/*
+ * arch/um/Makefile remaps strrchr to kernel_strrchr; call the kernel
+ * name directly to avoid glibc >= 2.43's C23 strrchr macro.
+ */
+char *kernel_strrchr(const char *, int);
+
 #define PATH_LEN_V1 256
 
 /* unsigned time_t works until year 2106 */
@@ -153,7 +159,7 @@ static int absolutize(char *to, int size, char *from)
 			   errno);
 		return -1;
 	}
-	slash = strrchr(from, '/');
+	slash = kernel_strrchr(from, '/');
 	if (slash != NULL) {
 		*slash = '\0';
 		if (chdir(from)) {

arch/um/include/asm/pgtable.h

@@ -112,13 +112,12 @@ static inline int pte_none(pte_t pte)
  */
 static inline int pte_read(pte_t pte)
 {
-	return((pte_get_bits(pte, _PAGE_USER)) &&
-	       !(pte_get_bits(pte, _PAGE_PROTNONE)));
+	return !pte_get_bits(pte, _PAGE_PROTNONE);
 }
 
-static inline int pte_exec(pte_t pte){
-	return((pte_get_bits(pte, _PAGE_USER)) &&
-	       !(pte_get_bits(pte, _PAGE_PROTNONE)));
+static inline int pte_exec(pte_t pte)
+{
+	return !pte_get_bits(pte, _PAGE_PROTNONE);
 }
 
 static inline int pte_write(pte_t pte)

arch/um/kernel/skas/stub.c

@@ -146,7 +146,7 @@ stub_signal_interrupt(int sig, siginfo_t *info, void *p)
 		/* Receive the FDs */
 		num_fds = 0;
 		fd_msg = msghdr.msg_control;
-		fd_map = (void *)&CMSG_DATA(fd_msg);
+		fd_map = (void *)CMSG_DATA(fd_msg);
 		if (res == iov.iov_len && msghdr.msg_controllen > sizeof(struct cmsghdr))
 			num_fds = (fd_msg->cmsg_len - CMSG_LEN(0)) / sizeof(int);
 

arch/um/kernel/skas/uaccess.c

@@ -170,8 +170,8 @@ static int strncpy_chunk_from_user(unsigned long from, int len, void *arg)
 	char **to_ptr = arg, *to = *to_ptr;
 	int n;
 
-	strncpy(to, (void *) from, len);
-	n = strnlen(to, len);
+	n = strnlen((void *) from, len);
+	memcpy_and_pad(to, len, (void *) from, n, 0);
 	*to_ptr += n;
 
 	if (n < len)

arch/um/kernel/tlb.c

@@ -29,10 +29,9 @@ static int kern_map(struct mm_id *mm_idp,
 		    unsigned long virt, unsigned long len, int prot,
 		    int phys_fd, unsigned long long offset)
 {
-	/* TODO: Why is executable needed to be always set in the kernel? */
 	return os_map_memory((void *)virt, phys_fd, offset, len,
 			     prot & UM_PROT_READ, prot & UM_PROT_WRITE,
-			     1);
+			     prot & UM_PROT_EXEC);
 }
 
 static int kern_unmap(struct mm_id *mm_idp,
@@ -165,6 +164,7 @@ int um_tlb_sync(struct mm_struct *mm)
 	unsigned long addr, next;
 	int ret = 0;
 
+	guard(spinlock_irqsave)(&mm->page_table_lock);
 	guard(spinlock_irqsave)(&mm->context.sync_tlb_lock);
 
 	if (mm->context.sync_tlb_range_to == 0)

arch/x86/Makefile.um

@@ -60,4 +60,6 @@ ELF_FORMAT := elf64-x86-64
 LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64
 LINK-y += -m64
 
+vdso-install-y += arch/x86/um/vdso/vdso.so.dbg
+
 endif

arch/x86/um/os-Linux/mcontext.c

@@ -4,7 +4,13 @@
 #include <linux/string.h>
 #include <sys/ucontext.h>
 #include <asm/ptrace.h>
+/*
+ * musl defines struct sigcontext in <bits/signal.h>.  Rename the kernel's
+ * copy to avoid redefinition while keeping the FP-state types available.
+ */
+#define sigcontext __kernel_sigcontext
 #include <asm/sigcontext.h>
+#undef sigcontext
 #include <sysdep/ptrace.h>
 #include <sysdep/mcontext.h>
 #include <arch.h>

arch/x86/um/vdso/Makefile

@@ -3,8 +3,6 @@
 # Building vDSO images for x86.
 #
 
-vdso-install-y += vdso.so
-
 # files to link into the vdso
 vobjs-y := vdso-note.o um_vdso.o
 

include/uapi/linux/um_timetravel.h

@@ -56,6 +56,9 @@ enum um_timetravel_shared_mem_fds {
 	 *	in the control message
 	 */
 	UM_TIMETRAVEL_SHARED_LOGFD,
+	/**
+	 * @UM_TIMETRAVEL_SHARED_MAX_FDS: number of fds listed here
+	 */
 	UM_TIMETRAVEL_SHARED_MAX_FDS,
 };
 
@@ -242,6 +245,7 @@ union um_timetravel_schedshm_client {
 		__u64 req_time;
 		__u64 name;
 	};
+	/* private: */
 	char reserve[128]; /* reserved for future usage */
 };
 
@@ -264,7 +268,7 @@ union um_timetravel_schedshm_client {
  *	is made by any client. Clients also must update this value when they
  *	insert/update an own request into the shared memory while not running
  *	themselves, and the new request is before than the current value.
- * current_time: Current time, can only be set by the client in running state
+ * @current_time: Current time, can only be set by the client in running state
  *	(indicated by @running_id), though that client may only run until @free_until,
  *	so it must remain smaller than @free_until.
  * @running_id: The current client in state running, set before a client is

mm/Kconfig

@@ -570,6 +570,7 @@ config SPLIT_PTE_PTLOCKS
 	depends on !ARM || CPU_CACHE_VIPT
 	depends on !PARISC || PA20
 	depends on !SPARC32
+	depends on !UML
 
 config ARCH_ENABLE_SPLIT_PMD_PTLOCK
 	bool