Messages in this thread | | | From | Thomas Gleixner <> | Subject | Re: [patch V3 15/20] x86/fpu/signal: Change return type of copy_fpregs_to_sigframe() helpers to boolean | Date | Tue, 21 Sep 2021 22:13:23 +0200 |
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On Tue, Sep 21 2021 at 12:58, Anders Roxell wrote: > On Wed, 8 Sept 2021 at 15:30, Thomas Gleixner <tglx@linutronix.de> wrote: >> >> Now that copy_fpregs_to_sigframe() returns boolean the individual return >> codes in the related helper functions do not make sense anymore. Change >> them to return boolean success/fail. >> >> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > > When I build and boot (qemu_x86_64) a defconfig kernel on from todays > next tag next-20210921 I see the following segmentation fault > > 2021-09-21T10:11:45 <6>[ 1.622922] mount (89) used greatest stack > depth: 14384 bytes left > 2021-09-21T10:11:45 <6>[ 1.664760] EXT4-fs (sda): re-mounted. Opts: > (null). Quota mode: none. > 2021-09-21T10:11:45 <6>[ 1.691041] mkdir (92) used greatest stack > depth: 14312 bytes left > 2021-09-21T10:11:45 <6>[ 1.713201] mount (93) used greatest stack > depth: 13720 bytes left > 2021-09-21T10:11:46 Starting syslogd: /etc/init.d/rcS: line 12: 101 > Segmentation fault $i start > > > I did a bisection and found this as the faulty patch [1]. When I > revert this patch I can't see the issue. > > We noticed that function 'save_xstate_epilog()' changes the polarity > of its return code for one of the return statements, and for its only > caller. but not for the other return statement. > > I tried this patch and I couldn't see the segmentation fault. > > diff --git a/arch/x86/kernel/fpu/signal.c b/arch/x86/kernel/fpu/signal.c > index 445c57c9c539..61eeebc04427 100644 > --- a/arch/x86/kernel/fpu/signal.c > +++ b/arch/x86/kernel/fpu/signal.c > @@ -104,7 +104,7 @@ static inline int save_xstate_epilog(void __user > *buf, int ia32_frame) > err = __copy_to_user(&x->i387.sw_reserved, sw_bytes, sizeof(*sw_bytes)); > > if (!use_xsave()) > - return err; > + return !err;
Oops. Good catch. Care to send a proper patch for this?
Thanks,
tglx
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