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From: Ard Biesheuvel <ardb@kernel.org>
To: linux-arm-kernel@lists.infradead.org, linux@armlinux.org.uk
Cc: Ard Biesheuvel <ardb@kernel.org>,
	Nicolas Pitre <nico@fluxnic.net>, Arnd Bergmann <arnd@arndb.de>,
	Kees Cook <keescook@chromium.org>,
	Keith Packard <keithpac@amazon.com>,
	Linus Walleij <linus.walleij@linaro.org>,
	Nick Desaulniers <ndesaulniers@google.com>,
	Tony Lindgren <tony@atomide.com>, Marc Zyngier <maz@kernel.org>,
	Vladimir Murzin <vladimir.murzin@arm.com>,
	Jesse Taube <mr.bossman075@gmail.com>
Subject: [PATCH v3 14/14] ARM: v7m: enable support for IRQ stacks
Date: Fri,  3 Dec 2021 11:09:03 +0100	[thread overview]
Message-ID: <20211203100903.334206-15-ardb@kernel.org> (raw)
In-Reply-To: <20211203100903.334206-1-ardb@kernel.org>

Enable support for IRQ stacks on !MMU, and add the code to the IRQ entry
path to switch to the IRQ stack if not running from it already.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm/Kconfig            |  1 -
 arch/arm/kernel/entry-v7m.S | 17 +++++++++++++++--
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 50ae5286f59b..359a3b85c8b3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1158,7 +1158,6 @@ config CURRENT_POINTER_IN_TPIDRURO
 
 config IRQSTACKS
 	def_bool y
-	depends on MMU
 	select HAVE_IRQ_EXIT_ON_IRQ_STACK
 	select HAVE_SOFTIRQ_ON_OWN_STACK
 
diff --git a/arch/arm/kernel/entry-v7m.S b/arch/arm/kernel/entry-v7m.S
index 4e0d318b67c6..de8a60363c85 100644
--- a/arch/arm/kernel/entry-v7m.S
+++ b/arch/arm/kernel/entry-v7m.S
@@ -40,11 +40,24 @@ __irq_entry:
 	@ Invoke the IRQ handler
 	@
 	mov	r0, sp
-	stmdb	sp!, {lr}
+	ldr_this_cpu sp, irq_stack_ptr, r1, r2
+
+	@
+	@ If we took the interrupt while running in the kernel, we may already
+	@ be using the IRQ stack, so revert to the original value in that case.
+	@
+	subs	r2, sp, r0		@ SP above bottom of IRQ stack?
+	rsbscs	r2, r2, #THREAD_SIZE	@ ... and below the top?
+	movcs	sp, r0
+
+	push	{r0, lr}		@ preserve LR and original SP
+
 	@ routine called with r0 = struct pt_regs *
 	bl	generic_handle_arch_irq
 
-	pop	{lr}
+	pop	{r0, lr}
+	mov	sp, r0
+
 	@
 	@ Check for any pending work if returning to user
 	@
-- 
2.30.2


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  parent reply	other threads:[~2021-12-03 10:17 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-03 10:08 [PATCH v3 00/14] ARM: enable IRQ stacks and vmap'ed stacks for UP Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 01/14] ARM: riscpc: use GENERIC_IRQ_MULTI_HANDLER Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 02/14] ARM: footbridge: " Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 03/14] ARM: iop32x: offset IRQ numbers by 1 Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 04/14] ARM: iop32x: use GENERIC_IRQ_MULTI_HANDLER Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 05/14] ARM: remove old-style irq entry Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 06/14] irqchip: nvic: Use GENERIC_IRQ_MULTI_HANDLER Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 07/14] ARM: entry: preserve thread_info pointer in switch_to Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 08/14] ARM: module: implement support for PC-relative group relocations Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 09/14] ARM: assembler: add optimized ldr/str macros to load variables from memory Ard Biesheuvel
2021-12-03 10:08 ` [PATCH v3 10/14] ARM: percpu: add SMP_ON_UP support Ard Biesheuvel
2021-12-03 10:09 ` [PATCH v3 11/14] ARM: use TLS register for 'current' on !SMP as well Ard Biesheuvel
2021-12-03 10:09 ` [PATCH v3 12/14] ARM: smp: defer TPIDRURO update for SMP v6 configurations too Ard Biesheuvel
2021-12-03 10:09 ` [PATCH v3 13/14] ARM: implement THREAD_INFO_IN_TASK for uniprocessor systems Ard Biesheuvel
2021-12-03 10:09 ` Ard Biesheuvel [this message]
2021-12-03 10:46 ` [PATCH v3 00/14] ARM: enable IRQ stacks and vmap'ed stacks for UP Vladimir Murzin
2021-12-03 12:53 ` Marc Zyngier
2021-12-05  0:38   ` Linus Walleij

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