From: Dan Carpenter <dan.carpenter@oracle.com>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: linuxppc-dev@lists.ozlabs.org
Subject: WARN_ON() is buggy for 32 bit systems
Date: Wed, 26 Jan 2022 14:56:16 +0300 [thread overview]
Message-ID: <20220126115616.GY1978@kadam> (raw)
Hi Michael,
Commit e432fe97f3e5 ("powerpc/bug: Cast to unsigned long before passing
to inline asm") breaks WARN_ON() for 32 bit systems.
arch/powerpc/include/asm/bug.h
109 #define WARN_ON(x) ({ \
110 bool __ret_warn_on = false; \
111 do { \
112 if (__builtin_constant_p((x))) { \
113 if (!(x)) \
114 break; \
115 __WARN(); \
116 __ret_warn_on = true; \
117 } else { \
118 __label__ __label_warn_on; \
119 \
120 WARN_ENTRY(PPC_TLNEI " %4, 0", \
121 BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN), \
122 __label_warn_on, \
123 "r" ((__force long)(x))); \
^^^^
If the code is "if (WARN_ON(some_u64)) {" then the cast to long will
truncate away the high bits so it's wrong. (Or at least that's how it
works on x86, I'm working on a work around for Smatch to be able to
parse this WARN_ON(). I don't know anything about PowerPC.)
124 break; \
125 __label_warn_on: \
126 __ret_warn_on = true; \
127 } \
128 } while (0); \
129 unlikely(__ret_warn_on); \
130 })
regards,
dan carpenter
next reply other threads:[~2022-01-26 12:26 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-26 11:56 Dan Carpenter [this message]
2022-01-26 12:21 ` WARN_ON() is buggy for 32 bit systems Christophe Leroy
2022-01-26 13:49 ` Dan Carpenter
2022-01-27 11:10 ` Michael Ellerman
2022-01-27 13:37 ` Dan Carpenter
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220126115616.GY1978@kadam \
--to=dan.carpenter@oracle.com \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mpe@ellerman.id.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.