From: Will Deacon <will@kernel.org>
To: linux-arm-kernel@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
Vladimir Murzin <vladimir.murzin@arm.com>,
Arnd Bergmann <arnd@arndb.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Linus Walleij <linusw@kernel.org>,
linux-kernel@vger.kernel.org, Mostafa Saleh <smostafa@google.com>,
Marc Zyngier <maz@kernel.org>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <ljs@kernel.org>,
Oliver Upton <oupton@kernel.org>, Will Deacon <will@kernel.org>,
Ard Biesheuvel <ardb@kernel.org>
Subject: [PATCH 15/21] arm64: entry: Point SP_EL0 at the overflow stack
Date: Mon, 7 Sep 2026 17:42:40 +0100 [thread overview]
Message-ID: <20260907164247.17223-16-will@kernel.org> (raw)
In-Reply-To: <20260907164247.17223-1-will@kernel.org>
With SP_EL0 now available for use in the kernel, point it at the
overflow stack so that exception entry from EL1h will later be able to
switch to the overflow stack by writing to SPSel.
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
---
arch/arm64/kernel/entry.S | 2 ++
arch/arm64/kernel/head.S | 3 +++
arch/arm64/kernel/smp.c | 12 ++++++++++--
3 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index a45be0a837c8..6958ee238649 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -227,6 +227,8 @@ alternative_cb_end
mrs x21, sp_el0
ldr_this_cpu tsk, __entry_task, x20
msr tpidrro_el0, tsk
+ adr_this_cpu x19, overflow_stack + OVERFLOW_STACK_SIZE, x20
+ msr sp_el0, x19
/*
* Ensure MDSCR_EL1.SS is clear, since we can unmask debug exceptions
diff --git a/arch/arm64/kernel/head.S b/arch/arm64/kernel/head.S
index c33551ee6572..27a19e1a0ee6 100644
--- a/arch/arm64/kernel/head.S
+++ b/arch/arm64/kernel/head.S
@@ -210,6 +210,9 @@ SYM_CODE_END(preserve_boot_args)
ldr w\tmp2, [\tsk, #TSK_TI_CPU]
ldr \tmp1, [\tmp1, \tmp2, lsl #3]
set_this_cpu_offset \tmp1
+
+ adr_this_cpu \tmp1, overflow_stack + OVERFLOW_STACK_SIZE, \tmp2
+ msr sp_el0, \tmp1
.endm
/*
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c
index 702dee8d0db5..4c122d6598de 100644
--- a/arch/arm64/kernel/smp.c
+++ b/arch/arm64/kernel/smp.c
@@ -51,6 +51,7 @@
#include <asm/processor.h>
#include <asm/smp_plat.h>
#include <asm/sections.h>
+#include <asm/stacktrace.h>
#include <asm/tlbflush.h>
#include <asm/ptrace.h>
#include <asm/virt.h>
@@ -448,8 +449,15 @@ void __init smp_cpus_done(unsigned int max_cpus)
static void __init set_boot_cpu_offset(void)
{
- asm volatile("msr tpidr_el1, %0"
- :: "r" (per_cpu_offset(0)) : "memory");
+ u64 ovf_sp = (u64)raw_cpu_ptr(overflow_stack) + OVERFLOW_STACK_SIZE;
+
+ asm volatile(
+ " msr tpidr_el1, %1\n"
+ " add %0, %0, %1\n"
+ " msr sp_el0, %0" /* Update the overflow stack pointer */
+ : "+r" (ovf_sp)
+ : "r" (per_cpu_offset(0))
+ : "memory");
}
void __init smp_prepare_boot_cpu(void)
--
2.55.0.979.g7e5102b832-goog
next prev parent reply other threads:[~2026-09-07 16:44 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-07 16:42 [PATCH 00/21] arm64: Move overflow sp into SP_EL1 and kernel sp into SP_EL0 Will Deacon
2026-09-07 16:42 ` [PATCH 01/21] arm64: entry: Defer setting of TPIDRRO_EL0 until exit to userspace Will Deacon
2026-09-11 7:53 ` Jinjie Ruan
2026-09-07 16:42 ` [PATCH 02/21] arm64: entry: Only check for stack overflow on exceptions from EL1 Will Deacon
2026-09-07 16:42 ` [PATCH 03/21] arm64: stackprotector: Temporarily disable per-task stackprotector Will Deacon
2026-09-07 16:42 ` [PATCH 04/21] arm64: bpf: Add support for generating reads of TPIDRRO_EL0 Will Deacon
2026-09-07 16:42 ` [PATCH 05/21] KVM: arm64: Protect TPIDRRO_EL0 across guest entry/exit Will Deacon
2026-09-07 16:42 ` [PATCH 06/21] arm64: Store 'current' in TPIDRRO_EL0 instead of SP_EL0 Will Deacon
2026-09-08 13:19 ` David Laight
2026-09-11 12:57 ` Will Deacon
2026-09-07 16:42 ` [PATCH 07/21] selftests/bpf: arm64: Use TPIDRRO_EL0 instead of SP_EL0 for 'current' Will Deacon
2026-09-07 16:42 ` [PATCH 08/21] scripts/gdb: " Will Deacon
2026-09-07 16:42 ` [PATCH 09/21] arm64: stackprotector: Re-enable per-task stackprotector Will Deacon
2026-09-07 16:42 ` [PATCH 10/21] arm64: percpu: Specialise set_my_cpu_offset() for the primary CPU Will Deacon
2026-09-07 16:42 ` [PATCH 11/21] arm64: percpu: Annotate __kern_my_cpu_offset() as '__always_inline' Will Deacon
2026-09-07 16:42 ` [PATCH 12/21] KVM: arm64: Preserve handler/thread bit of EL1 mode in __finalise_el2() Will Deacon
2026-09-07 16:42 ` [PATCH 13/21] arm64: sdei: Guard most of asm/sdei.h with CONFIG_ARM_SDE_INTERFACE Will Deacon
2026-09-07 16:42 ` [PATCH 14/21] arm64: sdei: Support SDEI events from kernel handler and thread modes Will Deacon
2026-09-07 16:42 ` Will Deacon [this message]
2026-09-07 16:42 ` [PATCH 16/21] arm64: entry: Implement EL1t exception handlers for overflow stack Will Deacon
2026-09-07 16:42 ` [PATCH 17/21] arm64: entry: Use SPSel to switch to " Will Deacon
2026-09-07 16:42 ` [PATCH 18/21] arm64: entry: Split up kernel_ventry macro into separate helper macros Will Deacon
2026-09-07 16:42 ` [PATCH 19/21] arm64: entry: The great stack switcheroo Will Deacon
2026-09-08 11:30 ` Will Deacon
2026-09-07 16:42 ` [PATCH 20/21] arm64: tracing: Advertise a mode of EL1t in synthetic kernel regs Will Deacon
2026-09-07 16:42 ` [PATCH 21/21] arm64: Rename 'overflow_stack' and OVERFLOW_STACK_SIZE Will Deacon
2026-09-09 10:39 ` [PATCH 00/21] arm64: Move overflow sp into SP_EL1 and kernel sp into SP_EL0 Vladimir Murzin
2026-09-09 11:29 ` Will Deacon
2026-09-10 13:49 ` Vladimir Murzin
2026-09-11 12:57 ` Will Deacon
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