[PATCH 4.14 030/146] x86/dumpstack: Indicate in Oops whether PTI is configured and enabled

Greg Kroah-Hartman
2018-01-01T15:03:48Z

From: Vlastimil Babka <vbabka@suse.cz>

commit 5f26d76c3fd67c48806415ef8b1116c97beff8ba upstream.

CONFIG_PAGE_TABLE_ISOLATION is relatively new and intrusive feature that may
still have some corner cases which could take some time to manifest and be
fixed. It would be useful to have Oops messages indicate whether it was
enabled for building the kernel, and whether it was disabled during boot.

Example of fully enabled:

Oops: 0001 [#1] SMP PTI

Example of enabled during build, but disabled during boot:

Oops: 0001 [#1] SMP NOPTI

We can decide to remove this after the feature has been tested in the field
long enough.

[ tglx: Made it use boot_cpu_has() as requested by Borislav ]

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
Acked-by: Dave Hansen <dave.hansen@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Andy Lutomirsky <luto@kernel.org>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Laight <David.Laight@aculab.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: aliguori@amazon.com
Cc: bpetkov@suse.de
Cc: daniel.gruss@iaik.tugraz.at
Cc: hughd@google.com
Cc: jkosina@suse.cz
Cc: keescook@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/dumpstack.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/arch/x86/kernel/dumpstack.c
+++ b/arch/x86/kernel/dumpstack.c
@@ -297,11 +297,13 @@ int __die(const char *str, struct pt_reg
unsigned long sp;
#endif
printk(KERN_DEFAULT
- "%s: %04lx [#%d]%s%s%s%s\n", str, err & 0xffff, ++die_counter,
+ "%s: %04lx [#%d]%s%s%s%s%s\n", str, err & 0xffff, ++die_counter,
IS_ENABLED(CONFIG_PREEMPT) ? " PREEMPT" : "",
IS_ENABLED(CONFIG_SMP) ? " SMP" : "",
debug_pagealloc_enabled() ? " DEBUG_PAGEALLOC" : "",
- IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "");
+ IS_ENABLED(CONFIG_KASAN) ? " KASAN" : "",
+ IS_ENABLED(CONFIG_PAGE_TABLE_ISOLATION) ?
+ (boot_cpu_has(X86_FEATURE_PTI) ? " PTI" : " NOPTI") : "");

if (notify_die(DIE_OOPS, str, regs, err,
current->thread.trap_nr, SIGSEGV) == NOTIFY_STOP)