| Message ID | f3c873365cccce18b2f1889984bf521d3cfb68f2.1729770373.git.thehajime@gmail.com |
|---|---|
| State | RFC |
| Headers | show |
| Series | [RFC,01/13] fs: binfmt_elf_efpic: add architecture hook elf_arch_finalize_exec | expand |
On Thu, 2024-10-24 at 21:09 +0900, Hajime Tazaki wrote: > This commit updates the behavior of signal handling under !MMU > environment. 1) the stack preparation for the signal handlers and > 2) retoration of stack after rt_sigreturn(2) syscall. Those are typo: restoration > @@ -562,6 +574,20 @@ SYSCALL_DEFINE0(rt_sigreturn) > unsigned long sp = PT_REGS_SP(¤t->thread.regs); > struct rt_sigframe __user *frame = > (struct rt_sigframe __user *)(sp - sizeof(long)); > +#ifndef CONFIG_MMU > + /** > + * we enter here with: > + * > + * __restore_rt: > + * mov $15, %rax > + * call *%rax (translated from syscall) > + * > + * (code is from musl libc) > + * so, stack needs to be popped of "call"ed address before > + * looking at rt_sigframe. > + */ > + frame = (struct rt_sigframe __user *)((unsigned long)frame + sizeof(long)); > +#endif > struct ucontext __user *uc = &frame->uc; you shouldn't put code in the middle of variable declarations ... I see why, but probably just split #if/#else/#endif? johannes
On Fri, 25 Oct 2024 18:30:41 +0900, Johannes Berg wrote: > > On Thu, 2024-10-24 at 21:09 +0900, Hajime Tazaki wrote: > > This commit updates the behavior of signal handling under !MMU > > environment. 1) the stack preparation for the signal handlers and > > 2) retoration of stack after rt_sigreturn(2) syscall. Those are > > typo: restoration will fix it. > > @@ -562,6 +574,20 @@ SYSCALL_DEFINE0(rt_sigreturn) > > unsigned long sp = PT_REGS_SP(¤t->thread.regs); > > struct rt_sigframe __user *frame = > > (struct rt_sigframe __user *)(sp - sizeof(long)); > > +#ifndef CONFIG_MMU > > + /** > > + * we enter here with: > > + * > > + * __restore_rt: > > + * mov $15, %rax > > + * call *%rax (translated from syscall) > > + * > > + * (code is from musl libc) > > + * so, stack needs to be popped of "call"ed address before > > + * looking at rt_sigframe. > > + */ > > + frame = (struct rt_sigframe __user *)((unsigned long)frame + sizeof(long)); > > +#endif > > struct ucontext __user *uc = &frame->uc; > > you shouldn't put code in the middle of variable declarations ... > > I see why, but probably just split #if/#else/#endif? thanks, will reformat it to make it clear. -- Hajime
diff --git a/arch/x86/um/signal.c b/arch/x86/um/signal.c index 2cc8c2309022..ae9b231dd8f8 100644 --- a/arch/x86/um/signal.c +++ b/arch/x86/um/signal.c @@ -537,6 +537,18 @@ int setup_signal_stack_si(unsigned long stack_top, struct ksignal *ksig, /* could use a vstub here */ return err; +#ifndef CONFIG_MMU + /* + * we need to push handler address at top of stack, as + * __kernel_vsyscall, called after this returns with ret with + * stack contents, thus push the handler here. + */ + frame = (struct rt_sigframe __user *) ((unsigned long) frame - + sizeof(unsigned long)); + err |= __put_user((unsigned long)ksig->ka.sa.sa_handler, + (unsigned long *)frame); +#endif + if (err) return err; @@ -562,6 +574,20 @@ SYSCALL_DEFINE0(rt_sigreturn) unsigned long sp = PT_REGS_SP(¤t->thread.regs); struct rt_sigframe __user *frame = (struct rt_sigframe __user *)(sp - sizeof(long)); +#ifndef CONFIG_MMU + /** + * we enter here with: + * + * __restore_rt: + * mov $15, %rax + * call *%rax (translated from syscall) + * + * (code is from musl libc) + * so, stack needs to be popped of "call"ed address before + * looking at rt_sigframe. + */ + frame = (struct rt_sigframe __user *)((unsigned long)frame + sizeof(long)); +#endif struct ucontext __user *uc = &frame->uc; sigset_t set;
This commit updates the behavior of signal handling under !MMU environment. 1) the stack preparation for the signal handlers and 2) retoration of stack after rt_sigreturn(2) syscall. Those are needed as the stack usage on vfork(2) syscall is different. Signed-off-by: Hajime Tazaki <thehajime@gmail.com> --- arch/x86/um/signal.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)