From: Jeff Dike Date: Thu, 8 Mar 2007 04:41:26 +0000 (-0800) Subject: [PATCH] uml: arch_prctl should set thread fs X-Git-Tag: v2.6.21-rc4~85 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=44f5c4ced6ddee2f5f2e45fa45b93370245d85bd;p=linux-2.6 [PATCH] uml: arch_prctl should set thread fs In my previous x86_64 thread fix, I forgot to initialize thread.arch.fs in arch_prctl. A process calling arch_prctl to set %fs would lose it on the next context switch. It also turns out that you can switch to a process which is in the process of exiting and which has lost its mm. In this case, it's worse than useless to try to call arch_prctl on the host process. Signed-off-by: Jeff Dike Cc: Paolo 'Blaisorblade' Giarrusso Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/arch/um/sys-x86_64/syscalls.c b/arch/um/sys-x86_64/syscalls.c index 01b91f9fa7..b3f6350cac 100644 --- a/arch/um/sys-x86_64/syscalls.c +++ b/arch/um/sys-x86_64/syscalls.c @@ -103,6 +103,9 @@ long arch_prctl_skas(struct task_struct *task, int code, switch(code){ case ARCH_SET_FS: + current->thread.arch.fs = (unsigned long) ptr; + save_registers(pid, ¤t->thread.regs.regs); + break; case ARCH_SET_GS: save_registers(pid, ¤t->thread.regs.regs); break; @@ -140,9 +143,8 @@ long sys_clone(unsigned long clone_flags, unsigned long newsp, void arch_switch_to_skas(struct task_struct *from, struct task_struct *to) { - if(to->thread.arch.fs == 0) + if((to->thread.arch.fs == 0) || (to->mm == NULL)) return; arch_prctl_skas(to, ARCH_SET_FS, (void __user *) to->thread.arch.fs); } -