From: "Nicholas Piggin" <npiggin@gmail.com>
To: "Rohan McLure" <rmclure@linux.ibm.com>, <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v4 18/20] powerpc/64s: Fix comment on interrupt handler prologue
Date: Mon, 12 Sep 2022 21:51:57 +1000 [thread overview]
Message-ID: <CMUEGH54LATI.1D41E2W7W5M3I@bobo> (raw)
In-Reply-To: <20220824020548.62625-19-rmclure@linux.ibm.com>
On Wed Aug 24, 2022 at 12:05 PM AEST, Rohan McLure wrote:
> Interrupt handlers on 64s systems will often need to save register state
> from the interrupted process to make space for loading special purpose
> registers or for internal state.
>
> Fix a comment documenting a common code path macro in the beginning of
> interrupt handlers where r10 is saved to the PACA to afford space for
> the value of the CFAR. Comment is currently written as if r10-r12 are
> saved to PACA, but in fact only r10 is saved, with r11-r12 saved much
> later. The distance in code between these saves has grown over the many
> revisions of this macro. Fix this by signalling with a comment where
> r11-r12 are saved to the PACA.
Wondering if this kind of comment is useful at all really... But it is
better than broken comment.
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
> ---
> V1 -> V2: Given its own commit
> V2 -> V3: Annotate r11-r12 save locations with comment.
> ---
> arch/powerpc/kernel/exceptions-64s.S | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/kernel/exceptions-64s.S b/arch/powerpc/kernel/exceptions-64s.S
> index 3d0dc133a9ae..a3b51441b039 100644
> --- a/arch/powerpc/kernel/exceptions-64s.S
> +++ b/arch/powerpc/kernel/exceptions-64s.S
> @@ -281,7 +281,7 @@ BEGIN_FTR_SECTION
> mfspr r9,SPRN_PPR
> END_FTR_SECTION_IFSET(CPU_FTR_HAS_PPR)
> HMT_MEDIUM
> - std r10,IAREA+EX_R10(r13) /* save r10 - r12 */
> + std r10,IAREA+EX_R10(r13) /* save r10 */
> .if ICFAR
> BEGIN_FTR_SECTION
> mfspr r10,SPRN_CFAR
> @@ -321,7 +321,7 @@ END_FTR_SECTION_IFSET(CPU_FTR_CFAR)
> mfctr r10
> std r10,IAREA+EX_CTR(r13)
> mfcr r9
> - std r11,IAREA+EX_R11(r13)
> + std r11,IAREA+EX_R11(r13) /* save r11 - r12 */
> std r12,IAREA+EX_R12(r13)
>
> /*
> --
> 2.34.1
next prev parent reply other threads:[~2022-09-12 11:52 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
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 [this message]
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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