From: Mark Rutland <mark.rutland@arm.com>
To: linux-arm-kernel@lists.infradead.org
Cc: vladimir.murzin@arm.com, ryan.roberts@arm.com,
peterz@infradead.org, catalin.marinas@arm.com,
david.laight.linux@gmail.com, stable@vger.kernel.org,
ruanjinjie@huawei.com, james.morse@arm.com,
yang@os.amperecomputing.com, cl@gentwo.org, maz@kernel.org,
david@kernel.org, ljs@kernel.org, will@kernel.org,
ardb@kernel.org
Subject: Re: [PATCH v2 11/20] arm64: entry: sdei: Restore all clobberable GPRs
Date: Fri, 7 Aug 2026 12:35:52 +0100 [thread overview]
Message-ID: <anXDGLkN-DbQ5hga@J2N7QTR9R3> (raw)
In-Reply-To: <20260804170503.3513916-12-mark.rutland@arm.com>
On Tue, Aug 04, 2026 at 06:04:54PM +0100, Mark Rutland wrote:
> Currently __sdei_asm_handler() avoids restoring x20 to x27, as these are
> not be clobbered by existing code. This is correct today, but it makes
> it awkward to rework __sdei_asm_handler(). Given the rarity of SDEI
> events, restoring x20 to x27 should not have a measurable impact.
>
> Restore x20 to x27 when returning from an SDEI event handler. This will
> free up those GPRs for usage in __sdei_asm_handler() prior to return.
Sashiko noticed an error below that I'll fix for v3.
> - /* restore regs >x17 that we clobbered */
> + /* restore regs >x17 that firmware won't restore */
> mov x4, x19 // keep x4 for __sdei_asm_exit_trampoline
> - ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14]
> ldp x18, x19, [x4, #SDEI_EVENT_INTREGS + 16 * 9]
> + ldp x20, x21, [x4, #SDEI_EVENT_INTREGS + 16 * 10]
> + ldp x22, x23, [x4, #SDEI_EVENT_INTREGS + 16 * 11]
> + ldp x24, x25, [x4, #SDEI_EVENT_INTREGS + 16 * 12]
> + ldp x22, x27, [x4, #SDEI_EVENT_INTREGS + 16 * 13]
^^^
That should be 'x26'.
Mark.
> + ldp x28, x29, [x4, #SDEI_EVENT_INTREGS + 16 * 14]
> ldp lr, x1, [x4, #SDEI_EVENT_INTREGS + S_LR]
> mov sp, x1
>
> --
> 2.30.2
>
next prev parent reply other threads:[~2026-08-07 11:36 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-04 17:04 [PATCH v2 00/20] arm64: Preemptible this_cpu_*() operations Mark Rutland
2026-08-04 17:04 ` [PATCH v2 01/20] arm64: percpu: Fix this_cpu_write() casting Mark Rutland
2026-08-05 8:37 ` David Laight
2026-08-07 4:00 ` Jinjie Ruan
2026-08-04 17:04 ` [PATCH v2 02/20] arm64: percpu: Fix this_cpu_and() mask generation Mark Rutland
2026-08-05 9:14 ` David Laight
2026-08-05 13:02 ` Mark Rutland
2026-08-06 8:28 ` David Laight
2026-08-06 10:23 ` Mark Rutland
2026-08-07 9:52 ` Jinjie Ruan
2026-08-04 17:04 ` [PATCH v2 03/20] arm64: cmpxchg: LL/SC: Avoid redundant extension Mark Rutland
2026-08-04 17:04 ` [PATCH v2 04/20] arm64: cmpxchg128: LSE: Remove redundant operands Mark Rutland
2026-08-04 17:04 ` [PATCH v2 05/20] arm64: preempt: Simplify and optimize __preempt_count_dec_and_test() Mark Rutland
2026-08-04 17:04 ` [PATCH v2 06/20] arm64: preempt: Treat should_resched() as unlikely Mark Rutland
2026-08-04 17:04 ` [PATCH v2 07/20] arm64: ptrace: Always inline pt_regs_[read,write}_reg() Mark Rutland
2026-08-04 17:04 ` [PATCH v2 08/20] arm64: percpu: Factor out percpu offset asm Mark Rutland
2026-08-04 17:04 ` [PATCH v2 09/20] arm64: gpr-num: Add wxN aliases for wN registers Mark Rutland
2026-08-04 17:04 ` [PATCH v2 10/20] arm64: gpr-num: add __GPR_NUM() helper Mark Rutland
2026-08-04 17:04 ` [PATCH v2 11/20] arm64: entry: sdei: Restore all clobberable GPRs Mark Rutland
2026-08-07 11:35 ` Mark Rutland [this message]
2026-08-04 17:04 ` [PATCH v2 12/20] arm64: entry: sdei: Make 'tsk' available Mark Rutland
2026-08-04 17:04 ` [PATCH v2 13/20] arm64: percpu: Add infrastructure for preemptible this_cpu_*() ops Mark Rutland
2026-08-04 22:45 ` Pedro Falcato
2026-08-05 10:27 ` David Laight
2026-08-05 12:50 ` Pedro Falcato
2026-08-05 6:45 ` David Hildenbrand (Arm)
2026-08-05 6:47 ` David Hildenbrand (Arm)
2026-08-06 11:21 ` Mark Rutland
2026-08-06 11:32 ` David Hildenbrand (Arm)
2026-08-06 12:02 ` Mark Rutland
2026-08-06 13:25 ` David Laight
2026-08-06 13:30 ` David Hildenbrand (Arm)
2026-08-04 17:04 ` [PATCH v2 14/20] arm64: percpu: Implement preemptible read/write ops Mark Rutland
2026-08-05 9:24 ` Ryan Roberts
2026-08-05 12:08 ` David Laight
2026-08-05 13:34 ` Mark Rutland
2026-08-04 17:04 ` [PATCH v2 15/20] arm64: percpu: Implement preemptible void RMW ops Mark Rutland
2026-08-04 17:04 ` [PATCH v2 16/20] arm64: percpu: Implement preemptible return " Mark Rutland
2026-08-04 17:05 ` [PATCH v2 17/20] arm64: percpu: Implement preemptible XCHG ops Mark Rutland
2026-08-04 17:05 ` [PATCH v2 18/20] arm64: percpu: Implement preemptible CMPXCHG ops Mark Rutland
2026-08-04 17:05 ` [PATCH v2 19/20] arm64: percpu: Implement preemptible CMPXCHG128 ops Mark Rutland
2026-08-04 17:05 ` [PATCH v2 20/20] arm64: percpu: Remove _pcp_protect*() wrappers Mark Rutland
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