Messages in this thread | | | Date | Wed, 29 Nov 2017 14:03:59 -0800 | From | Guenter Roeck <> | Subject | Re: [08/24] x86/mm/kaiser: Map the dynamically-allocated LDTs |
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On Mon, Nov 27, 2017 at 11:49:07AM +0100, Ingo Molnar wrote: > From: Dave Hansen <dave.hansen@linux.intel.com> > > Normally, a process has a NULL mm->context.ldt. But, there is a > syscall for a process to set a new one. If a process does that, > the LDT be mapped into the user page tables, just like the > default copy. > > The original KAISER patch missed this case. > > Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Cc: Andy Lutomirski <luto@kernel.org> > Cc: Borislav Petkov <bp@alien8.de> > Cc: Brian Gerst <brgerst@gmail.com> > Cc: Denys Vlasenko <dvlasenk@redhat.com> > Cc: H. Peter Anvin <hpa@zytor.com> > Cc: Josh Poimboeuf <jpoimboe@redhat.com> > Cc: Linus Torvalds <torvalds@linux-foundation.org> > Cc: Peter Zijlstra <peterz@infradead.org> > Cc: Rik van Riel <riel@redhat.com> > Cc: daniel.gruss@iaik.tugraz.at > Cc: hughd@google.com > Cc: keescook@google.com > Cc: linux-mm@kvack.org > Cc: michael.schwarz@iaik.tugraz.at > Cc: moritz.lipp@iaik.tugraz.at > Cc: richard.fellner@student.tugraz.at > Link: https://lkml.kernel.org/r/20171123003455.275397F7@viggo.jf.intel.com > Signed-off-by: Ingo Molnar <mingo@kernel.org> > --- > arch/x86/kernel/ldt.c | 25 ++++++++++++++++++++----- > 1 file changed, 20 insertions(+), 5 deletions(-) > ... > + > /* The caller must call finalize_ldt_struct on the result. LDT starts zeroed. */ > static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries) > { > struct ldt_struct *new_ldt; > unsigned int alloc_size; > + int ret; > > if (num_entries > LDT_ENTRIES) > return NULL; > @@ -89,6 +100,12 @@ static struct ldt_struct *alloc_ldt_struct(unsigned int num_entries) > return NULL; > } > > + ret = kaiser_add_mapping((unsigned long)new_ldt->entries, alloc_size, > + __PAGE_KERNEL | _PAGE_GLOBAL);
This results in:
arch/x86/kernel/ldt.c: In function ‘alloc_ldt_struct’: arch/x86/kernel/ldt.c:104:6: warning: large integer implicitly truncated to unsigned type [-Woverflow] __PAGE_KERNEL | _PAGE_GLOBAL); ^
in ARCH=i386 builds with CONFIG_X86_PAE enabled. See https://groups.google.com/forum/#!topic/cros-kernel-buildreports/8R41aX07daU
Guenter
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