sparc: Add architecture support for clone3

Add support for the clone3 system call to the SPARC architectures.

The implementation follows the pattern of the original clone syscall.
However, instead of explicitly calling kernel_clone, the clone3
handler calls the generic sys_clone3 handler in kernel/fork.
In case no stack is provided, the parents stack is reused.

The return value convention for clone3 follows the regular kernel return
value convention (in contrast to the original clone/fork on SPARC).

Closes: https://github.com/sparclinux/issues/issues/10
Signed-off-by: Ludwig Rydberg <ludwig.rydberg@gaisler.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Andreas Larsson <andreas@gaisler.com>
Tested-by: Andreas Larsson <andreas@gaisler.com>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20260119144753.27945-3-ludwig.rydberg@gaisler.com
Signed-off-by: Andreas Larsson <andreas@gaisler.com>

diff --git a/arch/sparc/include/asm/syscalls.h b/arch/sparc/include/asm/syscalls.h
index 35575fbfb9dce94f0ebb8ced1af496b6780d0bed..282e62b66518330517a5b13b30a16dd054722acc 100644 (file)
--- a/arch/sparc/include/asm/syscalls.h
+++ b/arch/sparc/include/asm/syscalls.h
@@ -7,5 +7,6 @@ struct pt_regs;
 asmlinkage long sparc_fork(struct pt_regs *regs);
 asmlinkage long sparc_vfork(struct pt_regs *regs);
 asmlinkage long sparc_clone(struct pt_regs *regs);
+asmlinkage long sparc_clone3(struct pt_regs *regs);
 
 #endif /* _SPARC64_SYSCALLS_H */

diff --git a/arch/sparc/include/asm/unistd.h b/arch/sparc/include/asm/unistd.h
index 3380411a4537b160cea0ded288df78e331015af2..d6bc76706a7aa416dab25cdb6e6e82f54cb9891e 100644 (file)
--- a/arch/sparc/include/asm/unistd.h
+++ b/arch/sparc/include/asm/unistd.h
@@ -49,8 +49,6 @@
 #define __ARCH_WANT_COMPAT_STAT
 #endif
 
-#define __ARCH_BROKEN_SYS_CLONE3
-
 #ifdef __32bit_syscall_numbers__
 /* Sparc 32-bit only has the "setresuid32", "getresuid32" variants,
  * it never had the plain ones and there is no value to adding those

diff --git a/arch/sparc/kernel/entry.S b/arch/sparc/kernel/entry.S
index a3fdee4cd6fa318575d0115c4f0e8af8f94c2b59..ea51ef52c952a1baf805167ca4334a0cf8c8ad14 100644 (file)
--- a/arch/sparc/kernel/entry.S
+++ b/arch/sparc/kernel/entry.S
@@ -907,6 +907,21 @@ flush_patch_four:
        jmpl    %l1 + %lo(sparc_vfork), %g0
         add    %sp, STACKFRAME_SZ, %o0
 
+       .globl  __sys_clone3, flush_patch_five
+__sys_clone3:
+       mov     %o7, %l5
+flush_patch_five:
+       FLUSH_ALL_KERNEL_WINDOWS;
+       ld      [%curptr + TI_TASK], %o4
+       rd      %psr, %g4
+       WRITE_PAUSE
+       rd      %wim, %g5
+       WRITE_PAUSE
+       std     %g4, [%o4 + AOFF_task_thread + AOFF_thread_fork_kpsr]
+       add     %sp, STACKFRAME_SZ, %o0
+       call    sparc_clone3
+        mov    %l5, %o7
+
         .align  4
 linux_sparc_ni_syscall:
        sethi   %hi(sys_ni_syscall), %l7

diff --git a/arch/sparc/kernel/kernel.h b/arch/sparc/kernel/kernel.h
index 8328a3b78a44418095c67443cd4c39895bbe13c3..4ee85051521a323cacef7b40e3ecff334f45c0a3 100644 (file)
--- a/arch/sparc/kernel/kernel.h
+++ b/arch/sparc/kernel/kernel.h
@@ -18,6 +18,7 @@ extern int ncpus_probed;
 asmlinkage long sparc_clone(struct pt_regs *regs);
 asmlinkage long sparc_fork(struct pt_regs *regs);
 asmlinkage long sparc_vfork(struct pt_regs *regs);
+asmlinkage long sparc_clone3(struct pt_regs *regs);
 
 #ifdef CONFIG_SPARC64
 /* setup_64.c */

diff --git a/arch/sparc/kernel/process.c b/arch/sparc/kernel/process.c
index 7d69877511fac96a41b1699ebeb9eca8f4a4e120..d72fa066594303c8a964dc77b4d8a337efad29b0 100644 (file)
--- a/arch/sparc/kernel/process.c
+++ b/arch/sparc/kernel/process.c
@@ -12,6 +12,7 @@
 #include <linux/sched/task.h>
 #include <linux/sched/task_stack.h>
 #include <linux/signal.h>
+#include <linux/syscalls.h>
 
 #include "kernel.h"
 
@@ -118,3 +119,16 @@ asmlinkage long sparc_clone(struct pt_regs *regs)
 
        return ret;
 }
+
+asmlinkage long sparc_clone3(struct pt_regs *regs)
+{
+       unsigned long sz;
+       struct clone_args __user *cl_args;
+
+       synchronize_user_stack();
+
+       cl_args = (struct clone_args __user *)regs->u_regs[UREG_I0];
+       sz = regs->u_regs[UREG_I1];
+
+       return sys_clone3(cl_args, sz);
+}

diff --git a/arch/sparc/kernel/process_32.c b/arch/sparc/kernel/process_32.c
index 5a28c0e91bf15f32161423a4cfe1b4f4c19688d9..dd8c6c02b0f1677a573daad360576c5adc039d6b 100644 (file)
--- a/arch/sparc/kernel/process_32.c
+++ b/arch/sparc/kernel/process_32.c
@@ -247,6 +247,8 @@ clone_stackframe(struct sparc_stackf __user *dst,
  * Parent -->  %o0 == childs  pid, %o1 == 0
  * Child  -->  %o0 == parents pid, %o1 == 1
  *
+ * clone3() - Uses regular kernel return value conventions
+ *
  * NOTE: We have a separate fork kpsr/kwim because
  *       the parent could change these values between
  *       sys_fork invocation and when we reach here
@@ -261,11 +263,11 @@ extern void ret_from_kernel_thread(void);
 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 {
        u64 clone_flags = args->flags;
-       unsigned long sp = args->stack;
        unsigned long tls = args->tls;
        struct thread_info *ti = task_thread_info(p);
        struct pt_regs *childregs, *regs = current_pt_regs();
        char *new_stack;
+       unsigned long sp = args->stack ? args->stack : regs->u_regs[UREG_FP];
 
 #ifndef CONFIG_SMP
        if(last_task_used_math == current) {
@@ -350,13 +352,22 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
        childregs->psr &= ~PSR_EF;
        clear_tsk_thread_flag(p, TIF_USEDFPU);
 #endif
+       /* Handle return value conventions */
+       if (regs->u_regs[UREG_G1] == __NR_clone3) {
+               /* clone3() - use regular kernel return value convention */
+
+               /* Set the return value for the child. */
+               childregs->u_regs[UREG_I0] = 0;
+       } else {
+               /* clone()/fork() - use SunOS return value convention */
 
-       /* Set the return value for the child. */
-       childregs->u_regs[UREG_I0] = current->pid;
-       childregs->u_regs[UREG_I1] = 1;
+               /* Set the return value for the child. */
+               childregs->u_regs[UREG_I0] = current->pid;
+               childregs->u_regs[UREG_I1] = 1;
 
-       /* Set the return value for the parent. */
-       regs->u_regs[UREG_I1] = 0;
+               /* Set the return value for the parent. */
+               regs->u_regs[UREG_I1] = 0;
+       }
 
        if (clone_flags & CLONE_SETTLS)
                childregs->u_regs[UREG_G7] = tls;

diff --git a/arch/sparc/kernel/process_64.c b/arch/sparc/kernel/process_64.c
index 25781923788a03e1fad80b5674fa6e1ff86fefe8..e889da8e483583b93d6edb580ec72b5104d3152a 100644 (file)
--- a/arch/sparc/kernel/process_64.c
+++ b/arch/sparc/kernel/process_64.c
@@ -564,17 +564,19 @@ barf:
  * under SunOS are nothing short of bletcherous:
  * Parent -->  %o0 == childs  pid, %o1 == 0
  * Child  -->  %o0 == parents pid, %o1 == 1
+ *
+ * clone3() - Uses regular kernel return value conventions
  */
 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 {
        u64 clone_flags = args->flags;
-       unsigned long sp = args->stack;
        unsigned long tls = args->tls;
        struct thread_info *t = task_thread_info(p);
        struct pt_regs *regs = current_pt_regs();
        struct sparc_stackf *parent_sf;
        unsigned long child_stack_sz;
        char *child_trap_frame;
+       unsigned long sp = args->stack ? args->stack : regs->u_regs[UREG_FP];
 
        /* Calculate offset to stack_frame & pt_regs */
        child_stack_sz = (STACKFRAME_SZ + TRACEREG_SZ);
@@ -616,12 +618,25 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
        if (t->utraps)
                t->utraps[0]++;
 
-       /* Set the return value for the child. */
-       t->kregs->u_regs[UREG_I0] = current->pid;
-       t->kregs->u_regs[UREG_I1] = 1;
+       /* Handle return value conventions */
+       if (regs->u_regs[UREG_G1] == __NR_clone3) {
+               /* clone3() - use regular kernel return value convention */
+
+               /* Set the return value for the child. */
+               t->kregs->u_regs[UREG_I0] = 0;
+
+               /* Clear g1 to indicate user thread */
+               t->kregs->u_regs[UREG_G1] = 0;
+       } else {
+               /* clone()/fork() - use SunOS return value convention */
+
+               /* Set the return value for the child. */
+               t->kregs->u_regs[UREG_I0] = current->pid;
+               t->kregs->u_regs[UREG_I1] = 1;
 
-       /* Set the second return value for the parent. */
-       regs->u_regs[UREG_I1] = 0;
+               /* Set the second return value for the parent. */
+               regs->u_regs[UREG_I1] = 0;
+       }
 
        if (clone_flags & CLONE_SETTLS)
                t->kregs->u_regs[UREG_G7] = tls;

diff --git a/arch/sparc/kernel/syscalls.S b/arch/sparc/kernel/syscalls.S
index 0e8ab0602c360bdc267680e5000e22ec5766b5c1..96fe8763d70cebceed657ac98a13d2834fe5b40c 100644 (file)
--- a/arch/sparc/kernel/syscalls.S
+++ b/arch/sparc/kernel/syscalls.S
@@ -103,6 +103,12 @@ sys_clone:
        ba,pt   %xcc, sparc_clone
         add    %sp, PTREGS_OFF, %o0
 
+       .align  32
+__sys_clone3:
+       flushw
+       ba,pt   %xcc, sparc_clone3
+        add    %sp, PTREGS_OFF, %o0
+
        .globl  ret_from_fork
 ret_from_fork:
        /* Clear current_thread_info()->new_child. */
@@ -113,6 +119,8 @@ ret_from_fork:
        brnz,pt %o0, ret_sys_call
         ldx    [%g6 + TI_FLAGS], %l0
        ldx     [%sp + PTREGS_OFF + PT_V9_G1], %l1
+       brz,pt  %l1, ret_sys_call
+        nop
        call    %l1
         ldx    [%sp + PTREGS_OFF + PT_V9_G2], %o0
        ba,pt   %xcc, ret_sys_call

diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl
index 39aa26b6a50be7e02ba2400b797d128f8c6d3499..c0307bb098921f3e7072a139ebcaf6970aac2e57 100644 (file)
--- a/arch/sparc/kernel/syscalls/syscall.tbl
+++ b/arch/sparc/kernel/syscalls/syscall.tbl
@@ -480,7 +480,7 @@
 432    common  fsmount                         sys_fsmount
 433    common  fspick                          sys_fspick
 434    common  pidfd_open                      sys_pidfd_open
-# 435 reserved for clone3
+435    common  clone3                          __sys_clone3
 436    common  close_range                     sys_close_range
 437    common  openat2                 sys_openat2
 438    common  pidfd_getfd                     sys_pidfd_getfd