From 4e0aedace01573185805e663b02675f48d36f5a0 Mon Sep 17 00:00:00 2001 From: Andreas Larsson Date: Mon, 19 Jan 2026 15:47:52 +0100 Subject: [PATCH] sparc: Synchronize user stack on fork and clone [ Upstream commit e38eba3b77878ada327a572a41596a3b0b44e522 ] Flush all uncommitted user windows before calling the generic syscall handlers for clone, fork, and vfork. Prior to entering the arch common handlers sparc_{clone|fork|vfork}, the arch-specific syscall wrappers for these syscalls will attempt to flush all windows (including user windows). In the window overflow trap handlers on both SPARC{32|64}, if the window can't be stored (i.e due to MMU related faults) the routine backups the user window and increments a thread counter (wsaved). By adding a synchronization point after the flush attempt, when fault handling is enabled, any uncommitted user windows will be flushed. Link: https://sourceware.org/bugzilla/show_bug.cgi?id=31394 Closes: https://lore.kernel.org/sparclinux/fe5cc47167430007560501aabb28ba154985b661.camel@physik.fu-berlin.de/ Signed-off-by: Andreas Larsson Signed-off-by: Ludwig Rydberg Tested-by: John Paul Adrian Glaubitz Link: https://lore.kernel.org/r/20260119144753.27945-2-ludwig.rydberg@gaisler.com Signed-off-by: Andreas Larsson Signed-off-by: Sasha Levin --- arch/sparc/kernel/process.c | 38 +++++++++++++++++++++++-------------- 1 file changed, 24 insertions(+), 14 deletions(-) diff --git a/arch/sparc/kernel/process.c b/arch/sparc/kernel/process.c index 0442ab00518d..7d69877511fa 100644 --- a/arch/sparc/kernel/process.c +++ b/arch/sparc/kernel/process.c @@ -17,14 +17,18 @@ asmlinkage long sparc_fork(struct pt_regs *regs) { - unsigned long orig_i1 = regs->u_regs[UREG_I1]; + unsigned long orig_i1; long ret; struct kernel_clone_args args = { .exit_signal = SIGCHLD, - /* Reuse the parent's stack for the child. */ - .stack = regs->u_regs[UREG_FP], }; + synchronize_user_stack(); + + orig_i1 = regs->u_regs[UREG_I1]; + /* Reuse the parent's stack for the child. */ + args.stack = regs->u_regs[UREG_FP]; + ret = kernel_clone(&args); /* If we get an error and potentially restart the system @@ -40,16 +44,19 @@ asmlinkage long sparc_fork(struct pt_regs *regs) asmlinkage long sparc_vfork(struct pt_regs *regs) { - unsigned long orig_i1 = regs->u_regs[UREG_I1]; + unsigned long orig_i1; long ret; - struct kernel_clone_args args = { .flags = CLONE_VFORK | CLONE_VM, .exit_signal = SIGCHLD, - /* Reuse the parent's stack for the child. */ - .stack = regs->u_regs[UREG_FP], }; + synchronize_user_stack(); + + orig_i1 = regs->u_regs[UREG_I1]; + /* Reuse the parent's stack for the child. */ + args.stack = regs->u_regs[UREG_FP]; + ret = kernel_clone(&args); /* If we get an error and potentially restart the system @@ -65,15 +72,18 @@ asmlinkage long sparc_vfork(struct pt_regs *regs) asmlinkage long sparc_clone(struct pt_regs *regs) { - unsigned long orig_i1 = regs->u_regs[UREG_I1]; - unsigned int flags = lower_32_bits(regs->u_regs[UREG_I0]); + unsigned long orig_i1; + unsigned int flags; long ret; + struct kernel_clone_args args = {0}; - struct kernel_clone_args args = { - .flags = (flags & ~CSIGNAL), - .exit_signal = (flags & CSIGNAL), - .tls = regs->u_regs[UREG_I3], - }; + synchronize_user_stack(); + + orig_i1 = regs->u_regs[UREG_I1]; + flags = lower_32_bits(regs->u_regs[UREG_I0]); + args.flags = (flags & ~CSIGNAL); + args.exit_signal = (flags & CSIGNAL); + args.tls = regs->u_regs[UREG_I3]; #ifdef CONFIG_COMPAT if (test_thread_flag(TIF_32BIT)) {