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From: "Arnd Bergmann" <arnd@arndb.de>
To: "Christophe Leroy" <christophe.leroy@csgroup.eu>,
	"Nicholas Piggin" <npiggin@gmail.com>,
	"Rohan McLure" <rmclure@linux.ibm.com>,
	"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v4 02/20] powerpc: Use generic fallocate compatibility syscall
Date: Mon, 12 Sep 2022 13:07:56 +0200	[thread overview]
Message-ID: <be29926f-226e-48dc-871a-e29a54e80583@www.fastmail.com> (raw)
In-Reply-To: <77355969-0ffd-cd1f-5f0d-3cc7059fade6@csgroup.eu>

On Mon, Sep 12, 2022, at 1:00 PM, Christophe Leroy wrote:
> Le 12/09/2022 à 11:57, Arnd Bergmann a écrit :
>> On Mon, Sep 12, 2022, at 10:38 AM, Nicholas Piggin wrote:
>> 
>> The powerpc difference is that in little-endian mode, only
>> the 'len' argument is swapped but the 'offset' argument is
>> still high/low:
>> 
>> long compat_sys_fallocate(int fd, int mode, u32 offset1, u32 offset2,
>>                                      u32 len1, u32 len2)
>> {
>>         return ksys_fallocate(fd, mode, ((loff_t)offset1 << 32) | offset2,
>>                              merge_64(len1, len2));
>> }
>> 
>> It's probably best to first fix this by using merge_64(offset1,
>> offset2) and allow that patch to be backported to stable kernels,
>> before changing it over to the generic code in a separate patch
>> within that series.
>> 
>> A related issue seems to exist in ppc_fadvise64_64(), which
>> uses the wrong argument order on ppc32le compat tasks, in addition
>> to having at least three different calling conventions across
>> architectures.
>
> Do ppc32le exist at all ?
>
> Native ppc32 is be only, and I'm not aware that ppc64 is able to run 
> ppc32le compat tasks.

I'm not aware of anyone using it, but commit 6e944aed8859
("powerpc/64: Make COMPAT user-selectable disabled on littleendian
by default.") added support to the kernel, and commit
57f48b4b74e7 ("powerpc/compat_sys: swap hi/lo parts of 64-bit
syscall args in LE mode") changed the compat syscall helpers
to pass 64-bit arguments correctly but apparently got fallocate()
and fadvise64_64() wrong.

With Rohan's series, we use generic implementation, which
is the sensible ABI but the change is technically an ABI
change for ppc32le, and it makes sense to split the change
that fixes the behavior from the cleanup.

       Arnd

  reply	other threads:[~2022-09-12 11:09 UTC|newest]

Thread overview: 53+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-24  2:05 [PATCH v4 00/20] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-08-24  2:05 ` [PATCH v4 01/20] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-08-25  7:04   ` Andrew Donnellan
2022-09-12  8:20   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 02/20] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-12  8:38   ` Nicholas Piggin
2022-09-12  9:57     ` Arnd Bergmann
2022-09-12 11:00       ` Christophe Leroy
2022-09-12 11:07         ` Arnd Bergmann [this message]
2022-08-24  2:05 ` [PATCH v4 03/20] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-12  9:03   ` Nicholas Piggin
2022-09-15  4:36     ` Rohan McLure
2022-08-24  2:05 ` [PATCH v4 04/20] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-12  9:26   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 05/20] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-12  9:42   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 06/20] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-12  9:47   ` Nicholas Piggin
2022-09-15  5:06     ` Rohan McLure
2022-08-24  2:05 ` [PATCH v4 07/20] powerpc: Adopt SYSCALL_DEFINE for arch-specific " Rohan McLure
2022-09-12 10:04   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 08/20] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-12 10:33   ` Nicholas Piggin
2022-09-13  7:09     ` Rohan McLure
2022-08-24  2:05 ` [PATCH v4 09/20] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-12 10:42   ` Nicholas Piggin
2022-09-13  2:29     ` Michael Ellerman
2022-08-24  2:05 ` [PATCH v4 10/20] powerpc: Use common syscall handler type Rohan McLure
2022-09-12 10:56   ` Nicholas Piggin
2022-09-15  5:45     ` Rohan McLure
2022-09-16  1:02       ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 11/20] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-12 11:09   ` Nicholas Piggin
2022-09-15  5:47     ` Rohan McLure
2022-08-24  2:05 ` [PATCH v4 12/20] Revert "powerpc/syscall: Save r3 in regs->orig_r3" Rohan McLure
2022-09-12 11:14   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 13/20] powerpc: Provide syscall wrapper Rohan McLure
2022-09-12 11:26   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 14/20] powerpc/64s: Clear/restore caller gprs in syscall interrupt/return Rohan McLure
2022-09-12 11:47   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 15/20] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-12 11:49   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 16/20] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-08-24  2:05 ` [PATCH v4 17/20] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-12 12:17   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 18/20] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-12 11:51   ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 19/20] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-12 12:15   ` Nicholas Piggin
2022-09-15  6:55     ` Rohan McLure
2022-09-16  0:43       ` Nicholas Piggin
2022-08-24  2:05 ` [PATCH v4 20/20] powerpc/64e: Clear gprs on interrupt routine entry Rohan McLure
2022-09-12  0:55 ` [PATCH v4 00/20] powerpc: Syscall wrapper and register clearing Rohan McLure

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