From: Andreas Schwab <schwab@linux-m68k.org>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: Noah Goldstein <goldstein.w.n@gmail.com>,
libc-alpha@sourceware.org, carlos@systemhalted.org
Subject: Re: x86: Fixup some nits in longjmp asm implementation
Date: Thu, 04 Jan 2024 23:40:11 +0100 [thread overview]
Message-ID: <878r54soxg.fsf@igel.home> (raw)
In-Reply-To: <CAMe9rOq0db1w8YNSM3s1nfbRtpegBQC0qTBq_WU_LVLAdUPg0w@mail.gmail.com> (H. J. Lu's message of "Thu, 4 Jan 2024 14:22:44 -0800")
On Jan 04 2024, H.J. Lu wrote:
> #ifdef PIC
> -# define CALL_FAIL leaq longjmp_msg(%rip), %rdi; \
> - call __GI___fortify_fail
> +# define CALL_FAIL subq $8, %rsp; \
> + cfi_remember_state; \
> + cfi_def_cfa_offset(16); \
> + leaq longjmp_msg(%rip), %rdi; \
> + call __GI___fortify_fail; \
> + nop; \
> + cfi_restore_state
>
> I don't think NOP is required.
Is the unwind information correct without the nop? Without it, the
return address points to the following label. It is customary that a
noreturn call is followed by a nop to avoid that.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1
"And now for something completely different."
next prev parent reply other threads:[~2024-01-04 22:40 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-04 22:16 Noah Goldstein
2024-01-04 22:22 ` H.J. Lu
2024-01-04 22:40 ` Andreas Schwab [this message]
2024-01-04 23:07 ` Noah Goldstein
2024-01-04 23:42 ` H.J. Lu
2024-01-05 11:18 ` Andreas Schwab
2024-01-05 15:22 ` H.J. Lu
2024-01-05 16:42 ` Andreas Schwab
2024-01-04 23:25 ` Noah Goldstein
2024-01-05 16:33 ` H.J. Lu
2024-01-05 19:12 ` Noah Goldstein
2024-01-05 20:09 ` H.J. Lu
2024-01-05 22:00 ` Noah Goldstein
2024-01-05 22:29 ` H.J. Lu
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