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From: Ard Biesheuvel <ardb@kernel.org>
To: linux@armlinux.org.uk, linux-arm-kernel@lists.infradead.org
Cc: linux-hardening@vger.kernel.org, Ard Biesheuvel <ardb@kernel.org>,
	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>,
	Marc Zyngier <maz@kernel.org>
Subject: [PATCH v6 1/8] ARM: mm: switch to swapper_pg_dir early for vmap'ed stack
Date: Tue, 25 Jan 2022 10:14:46 +0100	[thread overview]
Message-ID: <20220125091453.1475246-2-ardb@kernel.org> (raw)
In-Reply-To: <20220125091453.1475246-1-ardb@kernel.org>

When onlining a CPU, switch to swapper_pg_dir as soon as possible so
that it is guaranteed that the vmap'ed stack is mapped before it is
used.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
 arch/arm/Kconfig        | 2 +-
 arch/arm/kernel/head.S  | 7 +++++++
 arch/arm/kernel/sleep.S | 7 +++++++
 3 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c32b79453ddf..359a3b85c8b3 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -128,7 +128,7 @@ config ARM
 	select RTC_LIB
 	select SYS_SUPPORTS_APM_EMULATION
 	select THREAD_INFO_IN_TASK
-	select HAVE_ARCH_VMAP_STACK if MMU && (!LD_IS_LLD || LLD_VERSION >= 140000) && !PM_SLEEP_SMP
+	select HAVE_ARCH_VMAP_STACK if MMU && (!LD_IS_LLD || LLD_VERSION >= 140000)
 	select TRACE_IRQFLAGS_SUPPORT if !CPU_V7M
 	# Above selects are sorted alphabetically; please add new ones
 	# according to that.  Thanks.
diff --git a/arch/arm/kernel/head.S b/arch/arm/kernel/head.S
index c04dd94630c7..500612d3da2e 100644
--- a/arch/arm/kernel/head.S
+++ b/arch/arm/kernel/head.S
@@ -424,6 +424,13 @@ ENDPROC(secondary_startup)
 ENDPROC(secondary_startup_arm)
 
 ENTRY(__secondary_switched)
+#if defined(CONFIG_VMAP_STACK) && !defined(CONFIG_ARM_LPAE)
+	@ Before using the vmap'ed stack, we have to switch to swapper_pg_dir
+	@ as the ID map does not cover the vmalloc region.
+	mrc	p15, 0, ip, c2, c0, 1	@ read TTBR1
+	mcr	p15, 0, ip, c2, c0, 0	@ set TTBR0
+	instr_sync
+#endif
 	adr_l	r7, secondary_data + 12		@ get secondary_data.stack
 	ldr	sp, [r7]
 	ldr	r0, [r7, #4]			@ get secondary_data.task
diff --git a/arch/arm/kernel/sleep.S b/arch/arm/kernel/sleep.S
index f909baf17912..a86a1d4f3461 100644
--- a/arch/arm/kernel/sleep.S
+++ b/arch/arm/kernel/sleep.S
@@ -119,6 +119,13 @@ ENTRY(cpu_resume_mmu)
 ENDPROC(cpu_resume_mmu)
 	.popsection
 cpu_resume_after_mmu:
+#if defined(CONFIG_VMAP_STACK) && !defined(CONFIG_ARM_LPAE)
+	@ Before using the vmap'ed stack, we have to switch to swapper_pg_dir
+	@ as the ID map does not cover the vmalloc region.
+	mrc	p15, 0, ip, c2, c0, 1	@ read TTBR1
+	mcr	p15, 0, ip, c2, c0, 0	@ set TTBR0
+	instr_sync
+#endif
 	bl	cpu_init		@ restore the und/abt/irq banked regs
 	mov	r0, #0			@ return zero on success
 	ldmfd	sp!, {r4 - r11, pc}
-- 
2.30.2


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  reply	other threads:[~2022-01-25  9:39 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-25  9:14 [PATCH v6 0/8] ARM vmap'ed and IRQ stacks roundup Ard Biesheuvel
2022-01-25  9:14 ` Ard Biesheuvel [this message]
2022-01-25  9:14 ` [PATCH v6 2/8] ARM: assembler: define a Kconfig symbol for group relocation support Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 3/8] ARM: smp: elide HWCAP_TLS checks or __entry_task updates on SMP+v6 Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 4/8] ARM: entry: avoid clobbering R9 in IRQ handler Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 5/8] ARM: mm: make vmalloc_seq handling SMP safe Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 6/8] ARM: iop: make iop_handle_irq() static Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 7/8] ARM: drop pointless SMP check on secondary startup path Ard Biesheuvel
2022-01-25  9:14 ` [PATCH v6 8/8] ARM: make get_current() and __my_cpu_offset() __always_inline Ard Biesheuvel
2022-01-25 20:48   ` Nick Desaulniers

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