On 11/6/19 6:05 PM, Josh Poimboeuf wrote:
On Wed, Nov 06, 2019 at 05:43:44PM -0500, Joe Lawrence wrote:
commit 6415b38bae26 ("x86/stacktrace: Enable HAVE_RELIABLE_STACKTRACE
for the ORC unwinder") marked the ORC unwinder as a "reliable" unwinder.
Update the help text to reflect that change: the frame pointer unwinder
is no longer the only one that provides HAVE_RELIABLE_STACKTRACE.
Signed-off-by: Joe Lawrence <joe.lawrence@xxxxxxxxxx>
---
arch/x86/Kconfig.debug | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index bf9cd83de777..69cdf0558c13 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -316,10 +316,6 @@ config UNWINDER_FRAME_POINTER
unwinder, but the kernel text size will grow by ~3% and the kernel's
overall performance will degrade by roughly 5-10%.
- This option is recommended if you want to use the livepatch
- consistency model, as this is currently the only way to get a
- reliable stack trace (CONFIG_HAVE_RELIABLE_STACKTRACE).
-
config UNWINDER_GUESS
bool "Guess unwinder"
depends on EXPERT
@@ -333,6 +329,10 @@ config UNWINDER_GUESS
useful in many cases. Unlike the other unwinders, it has no runtime
overhead.
+ This option is not recommended if you want to use the livepatch
+ consistency model, as this unwinder cannot guarantee reliable stack
+ traces.
+
I'm not sure whether this last hunk is helpful. At the very least the
wording of "not recommended" might be confusing because it's not even
possible to combine UNWINDER_GUESS+HAVE_RELIABLE_STACKTRACE.
arch/x86/Kconfig: select HAVE_RELIABLE_STACKTRACE if X86_64 && (UNWINDER_FRAME_POINTER || UNWINDER_ORC) && STACK_VALIDATION
Ah good point. The alternative would be to copy the recommended note to
both UNWINDER_FRAME_POINTER and UNWINDER_ORC, or at least remove the
"only" phrasing. I dunno, nobody has noticed it yet, so maybe the first
hunk would be good enough.
-- Joe
