Re: switching ARC to 64-bit time_t (Re: [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64)

From: Lukasz Majewski <lukma@denx.de>
To: Andreas Schwab <schwab@suse.de>
Cc: Florian Weimer <fweimer@redhat.com>,
	Palmer Dabbelt <palmerdabbelt@google.com>,
	GNU C Library <libc-alpha@sourceware.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Vineet Gupta <Vineet.Gupta1@synopsys.com>,
	Helmut Grohne <helmutg@debian.org>, Zong Li <zongbox@gmail.com>,
	debian-arm@lists.debian.org,
	Alistair Francis <alistair.francis@wdc.com>,
	Adhemerval Zanella <adhemerval.zanella@linaro.org>,
	"Maciej W. Rozycki" <macro@wdc.com>,
	Alistair Francis <alistair23@gmail.com>,
	arcml <linux-snps-arc@lists.infradead.org>,
	Joseph Myers <joseph@codesourcery.com>
Subject: Re: switching ARC to 64-bit time_t (Re: [RFC v6 07/23] RISC-V: Use 64-bit time_t and off_t for RV32 and RV64)
Date: Mon, 24 Feb 2020 12:13:25 +0100	[thread overview]
Message-ID: <20200224121325.6b2fff1d@jawa> (raw)
In-Reply-To: <mvmd0a4xo4w.fsf@suse.de>

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On Mon, 24 Feb 2020 11:42:23 +0100
Andreas Schwab <schwab@suse.de> wrote:

> On Feb 24 2020, Lukasz Majewski wrote:
> 
> > On Mon, 24 Feb 2020 11:23:51 +0100
> > Andreas Schwab <schwab@suse.de> wrote:
> >  
> >> On Feb 24 2020, Lukasz Majewski wrote:
> >>   
> >> > If I add those functions as hidden_alias then those would be
> >> > accessible inside glibc without PLT, but will not be exported
> >> > (and redirection for Y2038 will not work).    
> >> 
> >> They aren't?  PLT avoidance is about internal references, and uses
> >> a different name then the exported sybmol.
> >>   
> >
> > I'm probably not aware of something - but as done in the following
> > patch:
> >
> > https://github.com/lmajewski/y2038_glibc/commit/c96eeb73175961c4ac80fdd3b6adc132805387c9
> >
> > I do need to remove librt_hidden_proto / librt_hidden_def to have
> > proper symbols visible when I do want to use redirections.  
> 
> You cannot redirect to GLIBC_PRIVATE symbols, they are not suposed to
> be used by public interfaces.  All public interfaces need to use
> official versioned symbols.
> 

I've put those symbols to GLIBC_PRIVATE as up till now many more
functions in glibc needs conversion to support 64 bit time. I need
exported symbols to test if the redirection (and Y2038 safeness on ARM
in general) works.

I also do guess that when we will be heading to expose _TIME_BITS==64
to outside word I would need to add:

  GLIBC_2.3X {
	clock_settime64;
  }

for clock_settime64

and then:

#ifdef __USE_TIME_BITS64
# if defined(__REDIRECT_NTH)
extern int __REDIRECT_NTH (clock_settime, (clockid_t __clock_id, const
struct timespec *__tp), clock_settime64);
# else
# define clock_settime clock_settime64
# endif
#endif

Am I correct ?

> Andreas.
> 

Best regards,

Lukasz Majewski

--

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