From: Al Viro <viro@zeniv.linux.org.uk>
To: sparclinux@vger.kernel.org
Subject: [PATCH] sparc32: fix a braino in fault handling in csum_and_copy_..._user()
Date: Thu, 26 Oct 2023 03:16:13 +0100 [thread overview]
Message-ID: <20231026021613.GI800259@ZenIV> (raw)
Fault handler used to make non-trivial calls, so it needed
to set a stack frame up. Used to be
save ... - grab a stack frame, old %o... become %i...
....
ret - go back to address originally in %o7, currently %i7
restore - switch to previous stack frame, in delay slot
Non-trivial calls had been gone since ab5e8b331244 and that code should
have become
retl - go back to address in %o7
clr %o0 - have return value set to 0
What it had become instead was
ret - go back to address in %i7 - return address of *caller*
clr %o0 - have return value set to 0
which is not good, to put it mildly - we forcibly return 0 from
csum_and_copy_{from,to}_iter() (which is what the call of that
thing had been inlined into) and do that without dropping the
stack frame of said csum_and_copy_..._iter(). Confuses the
hell out of the caller of csum_and_copy_..._iter(), obviously...
Fixes: ab5e8b331244 "sparc32: propagate the calling conventions change down to __csum_partial_copy_sparc_generic()"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
arch/sparc/lib/checksum_32.S | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/sparc/lib/checksum_32.S b/arch/sparc/lib/checksum_32.S
index 84ad709cbecb..66eda40fce36 100644
--- a/arch/sparc/lib/checksum_32.S
+++ b/arch/sparc/lib/checksum_32.S
@@ -453,5 +453,5 @@ ccslow: cmp %g1, 0
* we only bother with faults on loads... */
cc_fault:
- ret
+ retl
clr %o0
--
2.39.2
next reply other threads:[~2023-10-26 2:16 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-26 2:16 Al Viro [this message]
2023-10-27 18:47 ` [PATCH] sparc32: fix a braino in fault handling in csum_and_copy_..._user() Sam Ravnborg
2023-10-27 19:02 ` Al Viro
2023-10-27 20:14 ` Sam Ravnborg
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