From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Zack Weinberg <zackw@panix.com>, libc-alpha@sourceware.org
Subject: Re: [PATCH v2 01/21] powerpc: Create stackframe information on syscall
Date: Mon, 7 May 2018 10:57:58 -0300 [thread overview]
Message-ID: <18fe7698-158a-f885-051a-5412201eb445@linaro.org> (raw)
In-Reply-To: <20180507024909.5598-1-zackw@panix.com>
On 06/05/2018 23:49, Zack Weinberg wrote:
> On 26 Feb 2018, Adhemerval Zanella wrote:
>> This patch adds a minimal stackframe creation on powerpc syscall
>> implementation so backtrace works correctly on a signal handler.
>
> I don't know powerpc well enough to know if this should be necessary.
> I think one of the powerpc arch maintainers should comment. I do have
> a couple questions:
>
>> +#ifdef __powerpc64__
>> + stdu r1, -FRAME_MIN_SIZE (r1)
>> + cfi_adjust_cfa_offset (FRAME_MIN_SIZE)
>> +#else
>> + stwu r1,-16(1)
>> + cfi_def_cfa_offset (16)
>> +#endif
>
> Why does this use cfa_adjust_cfa_offset for 64-bit but _def_ for 32-bit?
I am not well versed in CFI definition, so I was basically followed what
compiler is spilling in a usual function call back when I coded it.
>
>> +#ifdef __powerpc64__
>> + addi r1, r1, FRAME_MIN_SIZE
>> +#else
>> + addi r1,r1,16
>> +#endif
>
> If FRAME_MIN_SIZE were defined for ppc32, we could reduce the
> ifdeffage here.
>
>> + cfi_def_cfa_offset (0)
>> sc
>> PSEUDO_RET
>
> Shouldn't the stack adjustments be undone _after_ the 'sc'
> instruction? Actually, is it possible that a single
> cfi_def_cfa_offset (0) at the beginning of the function is all that's
> really needed here? It seems like backtrace should be able to handle
> leaf frames in general...
Indeed the single 'cfi_def_cfa_offset (0)' is suffice, I will change the
patch accordingly in next iteration.
next prev parent reply other threads:[~2018-05-07 13:58 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-26 21:03 [PATCH v2 00/21] nptl: Fix Race conditions in pthread cancellation (BZ#12683) Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 01/21] powerpc: Create stackframe information on syscall Adhemerval Zanella
2018-02-26 21:41 ` Andreas Schwab
2018-02-27 12:05 ` Adhemerval Zanella
2018-05-07 2:49 ` Zack Weinberg
2018-05-07 13:57 ` Adhemerval Zanella [this message]
2018-02-26 21:03 ` [PATCH v2 02/21] nptl: Fix testcases for new pthread cancellation mechanism Adhemerval Zanella
2018-02-26 21:43 ` Andreas Schwab
2018-02-27 12:05 ` Adhemerval Zanella
2018-05-07 2:49 ` Zack Weinberg
2018-05-07 17:13 ` Adhemerval Zanella
2018-05-08 13:35 ` Zack Weinberg
2018-05-08 17:26 ` Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 03/21] nptl: Fix Race conditions in pthread cancellation (BZ#12683) Adhemerval Zanella
2018-04-27 12:20 ` Zack Weinberg
2018-04-27 12:25 ` Adhemerval Zanella
2018-05-07 2:48 ` Zack Weinberg
2018-05-07 2:49 ` Zack Weinberg
2018-05-08 17:11 ` Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 04/21] nptl: x86_64: " Adhemerval Zanella
2018-05-07 2:49 ` Zack Weinberg
2018-05-08 17:55 ` Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 05/21] nptl: x32: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 06/21] nptl: i386: " Adhemerval Zanella
2018-05-07 2:49 ` Zack Weinberg
2018-05-08 17:56 ` Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 07/21] nptl: powerpc: " Adhemerval Zanella
2018-05-07 19:25 ` Tulio Magno Quites Machado Filho
2018-05-08 18:07 ` Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 08/21] nptl: aarch64: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 09/21] nptl: arm: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 10/21] nptl: s390: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 11/21] nptl: ia64: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 12/21] nptl: alpha: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 13/21] nptl: m68k: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 14/21] nptl: microblaze: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 15/21] nptl: tile: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 16/21] nptl: sparc: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 17/21] nptl: nios2: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 18/21] nptl: sh: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 19/21] nptl: mips: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 20/21] nptl: hppa: " Adhemerval Zanella
2018-02-26 21:03 ` [PATCH v2 21/21] nptl: riscv: " Adhemerval Zanella
2018-02-27 1:16 ` DJ Delorie
2018-02-27 13:03 ` Adhemerval Zanella
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