From: "Nicholas Piggin" <npiggin@gmail.com>
To: "Rohan McLure" <rmclure@linux.ibm.com>, <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH 05/23] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S
Date: Tue, 20 Sep 2022 10:51:18 +1000 [thread overview]
Message-ID: <CN0TF0H6I6FA.AJU2XR69ZV8O@bobo> (raw)
In-Reply-To: <20220916053300.786330-6-rmclure@linux.ibm.com>
On Fri Sep 16, 2022 at 3:32 PM AEST, Rohan McLure wrote:
> Restoring the register state of the interrupted thread involves issuing
> a large number of predictable loads to the kernel stack frame. Issue the
> REST_GPR{,S} macros to clearly signal when this is happening, and bunch
> together restores at the end of the interrupt handler where the saved
> value is not consumed earlier in the handler code.
>
> Signed-off-by: Rohan McLure <rmclure@linux.ibm.com>
> Reported-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
> ---
> V2 -> V3: New patch.
> V3 -> V4: Minimise restores in the unrecoverable window between
> restoring SRR0/1 and return from interrupt.
> ---
> arch/powerpc/kernel/entry_32.S | 33 +++++++++++++-------------------
> 1 file changed, 13 insertions(+), 20 deletions(-)
>
> diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
> index 44dfce9a60c5..e4b694cebc44 100644
> --- a/arch/powerpc/kernel/entry_32.S
> +++ b/arch/powerpc/kernel/entry_32.S
> @@ -68,7 +68,7 @@ prepare_transfer_to_handler:
> lwz r9,_MSR(r11) /* if sleeping, clear MSR.EE */
> rlwinm r9,r9,0,~MSR_EE
> lwz r12,_LINK(r11) /* and return to address in LR */
> - lwz r2, GPR2(r11)
> + REST_GPR(2, r11)
> b fast_exception_return
> _ASM_NOKPROBE_SYMBOL(prepare_transfer_to_handler)
> #endif /* CONFIG_PPC_BOOK3S_32 || CONFIG_E500 */
> @@ -144,7 +144,7 @@ ret_from_syscall:
> lwz r7,_NIP(r1)
> lwz r8,_MSR(r1)
> cmpwi r3,0
> - lwz r3,GPR3(r1)
> + REST_GPR(3, r1)
> syscall_exit_finish:
> mtspr SPRN_SRR0,r7
> mtspr SPRN_SRR1,r8
> @@ -152,8 +152,8 @@ syscall_exit_finish:
> bne 3f
> mtcr r5
>
> -1: lwz r2,GPR2(r1)
> - lwz r1,GPR1(r1)
> +1: REST_GPR(2, r1)
> + REST_GPR(1, r1)
> rfi
> #ifdef CONFIG_40x
> b . /* Prevent prefetch past rfi */
> @@ -165,10 +165,8 @@ syscall_exit_finish:
> REST_NVGPRS(r1)
> mtctr r4
> mtxer r5
> - lwz r0,GPR0(r1)
> - lwz r3,GPR3(r1)
> - REST_GPRS(4, 11, r1)
> - lwz r12,GPR12(r1)
> + REST_GPR(0, r1)
> + REST_GPRS(3, 12, r1)
> b 1b
>
> #ifdef CONFIG_44x
> @@ -260,9 +258,8 @@ fast_exception_return:
> beq 3f /* if not, we've got problems */
> #endif
>
> -2: REST_GPRS(3, 6, r11)
> - lwz r10,_CCR(r11)
> - REST_GPRS(1, 2, r11)
> +2: lwz r10,_CCR(r11)
> + REST_GPRS(1, 6, r11)
> mtcr r10
> lwz r10,_LINK(r11)
> mtlr r10
> @@ -277,7 +274,7 @@ fast_exception_return:
> mtspr SPRN_SRR0,r12
> REST_GPR(9, r11)
> REST_GPR(12, r11)
> - lwz r11,GPR11(r11)
> + REST_GPR(11, r11)
> rfi
> #ifdef CONFIG_40x
> b . /* Prevent prefetch past rfi */
> @@ -454,9 +451,8 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return)
> lwz r3,_MSR(r1); \
> andi. r3,r3,MSR_PR; \
> bne interrupt_return; \
> - lwz r0,GPR0(r1); \
> - lwz r2,GPR2(r1); \
> - REST_GPRS(3, 8, r1); \
> + REST_GPR(0, r1); \
> + REST_GPRS(2, 8, r1); \
> lwz r10,_XER(r1); \
> lwz r11,_CTR(r1); \
> mtspr SPRN_XER,r10; \
> @@ -475,11 +471,8 @@ _ASM_NOKPROBE_SYMBOL(interrupt_return)
> lwz r12,_MSR(r1); \
> mtspr exc_lvl_srr0,r11; \
> mtspr exc_lvl_srr1,r12; \
> - lwz r9,GPR9(r1); \
> - lwz r12,GPR12(r1); \
> - lwz r10,GPR10(r1); \
> - lwz r11,GPR11(r1); \
> - lwz r1,GPR1(r1); \
> + REST_GPRS(9, 12, r1); \
> + REST_GPR(1, r1); \
> exc_lvl_rfi; \
> b .; /* prevent prefetch past exc_lvl_rfi */
>
> --
> 2.34.1
next prev parent reply other threads:[~2022-09-20 0:52 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-16 5:32 [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
2022-09-16 5:32 ` [PATCH 01/23] powerpc: Remove asmlinkage from syscall handler definitions Rohan McLure
2022-09-16 5:32 ` [PATCH 02/23] powerpc: Save caller r3 prior to system_call_exception Rohan McLure
2022-09-16 5:32 ` [PATCH 03/23] powerpc: Add ZEROIZE_GPRS macros for register clears Rohan McLure
2022-09-16 5:32 ` [PATCH 04/23] powerpc/64s: Use {ZEROIZE,SAVE,REST}_GPRS macros in sc, scv 0 handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 05/23] powerpc/32: Clarify interrupt restores with REST_GPR macro in entry_32.S Rohan McLure
2022-09-20 0:51 ` Nicholas Piggin [this message]
2022-09-16 5:32 ` [PATCH 06/23] powerpc/64e: Clarify register saves and clears with {SAVE,ZEROIZE}_GPRS Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 07/23] powerpc/64s: Fix comment on interrupt handler prologue Rohan McLure
2022-09-20 0:55 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 08/23] powerpc: Fix fallocate and fadvise64_64 compat parameter combination Rohan McLure
2022-09-16 6:54 ` Arnd Bergmann
2022-09-20 1:01 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 09/23] asm-generic: compat: Support BE for long long args in 32-bit ABIs Rohan McLure
2022-09-20 1:06 ` Nicholas Piggin
2022-09-20 7:09 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 10/23] powerpc: Use generic fallocate compatibility syscall Rohan McLure
2022-09-16 6:56 ` Arnd Bergmann
2022-09-16 5:32 ` [PATCH 11/23] powerpc/32: Remove powerpc select specialisation Rohan McLure
2022-09-16 5:32 ` [PATCH 12/23] powerpc: Remove direct call to personality syscall handler Rohan McLure
2022-09-16 5:32 ` [PATCH 13/23] powerpc: Remove direct call to mmap2 syscall handlers Rohan McLure
2022-09-16 5:32 ` [PATCH 14/23] powerpc: Provide do_ppc64_personality helper Rohan McLure
2022-09-16 5:32 ` [PATCH 15/23] powerpc: Adopt SYSCALL_DEFINE for arch-specific syscall handlers Rohan McLure
2022-09-16 5:48 ` Rohan McLure
2022-09-20 1:24 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 16/23] powerpc: Include all arch-specific syscall prototypes Rohan McLure
2022-09-20 1:27 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 17/23] powerpc: Enable compile-time check for syscall handlers Rohan McLure
2022-09-20 1:30 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 18/23] powerpc: Use common syscall handler type Rohan McLure
2022-09-20 1:39 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 19/23] powerpc: Provide syscall wrapper Rohan McLure
2022-09-20 1:59 ` Nicholas Piggin
2022-09-21 3:44 ` Rohan McLure
2022-09-16 5:32 ` [PATCH 20/23] powerpc/64s: Clear/restore caller gprs in syscall interrupt/return Rohan McLure
2022-09-20 2:03 ` Nicholas Piggin
2022-09-20 4:54 ` Rohan McLure
2022-09-21 5:33 ` Rohan McLure
2022-09-20 2:07 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 21/23] powerpc/64: Add INTERRUPT_SANITIZE_REGISTERS Kconfig Rohan McLure
2022-09-20 2:10 ` Nicholas Piggin
2022-09-16 5:32 ` [PATCH 22/23] powerpc/64s: Clear gprs on interrupt routine entry in Book3S Rohan McLure
2022-09-20 2:27 ` Nicholas Piggin
2022-09-16 5:33 ` [PATCH 23/23] powerpc/64e: Clear gprs on interrupt routine entry on Book3E Rohan McLure
2022-09-16 5:58 ` [PATCH 00/23] powerpc: Syscall wrapper and register clearing Rohan McLure
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