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sparc: Synchronize user stack on fork and clone

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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 <andreas@gaisler.com>
Signed-off-by: Ludwig Rydberg <ludwig.rydberg@gaisler.com>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/20260119144753.27945-2-ludwig.rydberg@gaisler.com
Signed-off-by: Andreas Larsson <andreas@gaisler.com>
This commit is contained in:
Andreas Larsson 2026-01-19 15:47:52 +01:00
parent dc2f4d41a6
commit e38eba3b77
1 changed files with 24 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

38
arch/sparc/kernel/process.c
View file

@ -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)) {