From: tip-bot for Ingo Molnar <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, brgerst@gmail.com, jgross@suse.com,
hpa@zytor.com, peterz@infradead.org, bp@alien8.de,
tglx@linutronix.de, dvlasenk@redhat.com,
linux-kernel@vger.kernel.org, luto@kernel.org,
torvalds@linux-foundation.org
Subject: [tip:x86/paravirt] x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call()
Date: Fri, 24 May 2019 00:59:23 -0700 [thread overview]
Message-ID: <tip-11e86dc7f2746210f9c7dc10deaa7658f8dc8350@git.kernel.org> (raw)
In-Reply-To: <20190425095039.GC115378@gmail.com>
Commit-ID: 11e86dc7f2746210f9c7dc10deaa7658f8dc8350
Gitweb: https://git.kernel.org/tip/11e86dc7f2746210f9c7dc10deaa7658f8dc8350
Author: Ingo Molnar <mingo@kernel.org>
AuthorDate: Thu, 25 Apr 2019 11:50:39 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 25 Apr 2019 12:00:44 +0200
x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call()
paravirt_patch_call() currently handles patching failures inconsistently:
we generate a warning in the retpoline case, but don't in other cases where
we might end up with a non-working kernel as well.
So just convert it all to a BUG_ON(), these patching calls are *not* supposed
to fail, and if they do we want to know it immediately.
This also makes the kernel smaller and removes an #ifdef ugly.
I tried it with a richly paravirt-enabled kernel and no patching bugs
were detected.
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: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190425095039.GC115378@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/kernel/paravirt.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/paravirt.c b/arch/x86/kernel/paravirt.c
index 7f9121f2fdac..544d386ded45 100644
--- a/arch/x86/kernel/paravirt.c
+++ b/arch/x86/kernel/paravirt.c
@@ -73,21 +73,21 @@ struct branch {
static unsigned paravirt_patch_call(void *insnbuf, const void *target,
unsigned long addr, unsigned len)
{
+ const int call_len = 5;
struct branch *b = insnbuf;
- unsigned long delta = (unsigned long)target - (addr+5);
+ unsigned long delta = (unsigned long)target - (addr+call_len);
- if (len < 5) {
-#ifdef CONFIG_RETPOLINE
- WARN_ONCE(1, "Failing to patch indirect CALL in %ps\n", (void *)addr);
-#endif
- return len; /* call too long for patch site */
+ if (len < call_len) {
+ pr_warn("paravirt: Failed to patch indirect CALL at %ps\n", (void *)addr);
+ /* Kernel might not be viable if patching fails, bail out: */
+ BUG_ON(1);
}
b->opcode = 0xe8; /* call */
b->delta = delta;
- BUILD_BUG_ON(sizeof(*b) != 5);
+ BUILD_BUG_ON(sizeof(*b) != call_len);
- return 5;
+ return call_len;
}
#ifdef CONFIG_PARAVIRT_XXL
next prev parent reply other threads:[~2019-05-24 8:00 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 13:41 [patch 0/3] x86/paravirt: Rework paravirt patching Thomas Gleixner
2019-04-24 13:41 ` [patch 1/3] x86/paravirt: Remove bogus extern declarations Thomas Gleixner
2019-04-25 7:31 ` [tip:x86/paravirt] " tip-bot for Thomas Gleixner
2019-05-24 7:58 ` tip-bot for Thomas Gleixner
2019-04-24 13:41 ` [patch 2/3] x86/paravirt: Unify 32/64 bit patch code Thomas Gleixner
2019-04-25 7:32 ` [tip:x86/paravirt] " tip-bot for Thomas Gleixner
2019-05-24 8:00 ` [tip:x86/paravirt] x86/paravirt: Unify the 32/64 bit paravirt patching code tip-bot for Thomas Gleixner
2019-04-24 13:41 ` [patch 3/3] x86/paravirt: Replace paravirt patch asm magic Thomas Gleixner
2019-04-25 6:52 ` Ingo Molnar
2019-04-25 7:22 ` Thomas Gleixner
2019-04-25 7:46 ` Juergen Gross
2019-04-25 8:10 ` [PATCH] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering Ingo Molnar
2019-04-25 9:17 ` [PATCH] x86/paravirt: Detect oversized patching bugs as they happen and BUG_ON() to avoid later crashes Ingo Molnar
2019-04-25 9:21 ` Peter Zijlstra
2019-04-25 9:50 ` x86/paravirt: Detect over-sized patching bugs in paravirt_patch_call() Ingo Molnar
2019-04-25 10:22 ` Peter Zijlstra
2019-04-25 10:57 ` Ingo Molnar
2019-04-25 11:30 ` Juergen Gross
2019-04-25 12:30 ` Juergen Gross
2019-04-25 11:40 ` Peter Zijlstra
2019-04-25 12:30 ` Peter Zijlstra
2019-05-24 7:59 ` tip-bot for Ingo Molnar [this message]
2019-05-24 7:58 ` [tip:x86/paravirt] x86/paravirt: Detect over-sized patching bugs in paravirt_patch_insns() tip-bot for Ingo Molnar
2019-05-24 8:01 ` [tip:x86/paravirt] x86/paravirt: Match paravirt patchlet field definition ordering to initialization ordering tip-bot for Ingo Molnar
2019-04-25 8:08 ` [patch 3/3] x86/paravirt: Replace paravirt patch asm magic Peter Zijlstra
2019-04-25 8:19 ` Peter Zijlstra
2019-04-25 9:20 ` Ingo Molnar
2019-05-24 8:00 ` [tip:x86/paravirt] x86/paravirt: Replace the " tip-bot for Thomas Gleixner
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