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From: Mark Brown <broonie@kernel.org>
To: Vincenzo Frascino <Vincenzo.Frascino@arm.com>,
	Will Deacon <will@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Brown <broonie@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	linux-arm-kernel@lists.infradead.org
Subject: [PATCH 10/10] arm64: vdso: Map the vDSO text with guarded pages when built for BTI
Date: Wed, 15 Apr 2020 14:07:49 +0100	[thread overview]
Message-ID: <20200415130750.18645-11-broonie@kernel.org> (raw)
In-Reply-To: <20200415130750.18645-1-broonie@kernel.org>

The kernel is responsible for mapping the vDSO into userspace processes,
including mapping the text section as executable. Handle the mapping of
the vDSO for BTI similarly, mapping the text section as guarded pages so
the BTI annotations in the vDSO become effective when they are present.

This will mean that we can have BTI active for the vDSO in processes that
do not otherwise support BTI. This should not be an issue for any expected
use of the vDSO.

Signed-off-by: Mark Brown <broonie@kernel.org>
---
 arch/arm64/kernel/vdso.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 354b11e27c07..9271b7774df0 100644
--- a/arch/arm64/kernel/vdso.c
+++ b/arch/arm64/kernel/vdso.c
@@ -142,6 +142,7 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
 				    int uses_interp)
 {
 	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
+	unsigned long gp_flags = 0;
 	void *ret;
 
 	vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;
@@ -160,10 +161,13 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
 	if (IS_ERR(ret))
 		goto up_fail;
 
+	if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti())
+		gp_flags = VM_ARM64_BTI;
+
 	vdso_base += PAGE_SIZE;
 	mm->context.vdso = (void *)vdso_base;
 	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,
-				       VM_READ|VM_EXEC|
+				       VM_READ|VM_EXEC|gp_flags|
 				       VM_MAYREAD|VM_MAYWRITE|VM_MAYEXEC,
 				       vdso_lookup[arch_index].cm);
 	if (IS_ERR(ret))
-- 
2.20.1


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  parent reply	other threads:[~2020-04-15 13:14 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-15 13:07 [PATCH 00/10] arm64: BTI kernel and vDSO support Mark Brown
2020-04-15 13:07 ` [PATCH 01/10] arm64: kernel: Convert to modern annotations for assembly functions Mark Brown
2020-04-15 13:07 ` [PATCH 02/10] arm64: bti: Support building kernel C code using BTI Mark Brown
2020-04-15 13:07 ` [PATCH 03/10] arm64: asm: Override SYM_FUNC_START when building the kernel with BTI Mark Brown
2020-04-15 13:07 ` [PATCH 04/10] arm64: Set GP bit in kernel page tables to enable BTI for the kernel Mark Brown
2020-04-28 17:24   ` Catalin Marinas
2020-04-28 18:03     ` Mark Brown
2020-04-29  7:40       ` Will Deacon
2020-04-29 10:10         ` Mark Brown
2020-04-15 13:07 ` [PATCH 05/10] arm64: mm: Mark module text as guarded pages Mark Brown
2020-04-27 15:07   ` Mark Brown
2020-04-15 13:07 ` [PATCH 06/10] arm64: bti: Provide Kconfig for kernel mode BTI Mark Brown
2020-04-15 13:07 ` [PATCH 07/10] arm64: asm: Provide a mechanism for generating ELF note for BTI Mark Brown
2020-04-15 13:07 ` [PATCH 08/10] arm64: vdso: Annotate " Mark Brown
2020-04-15 13:07 ` [PATCH 09/10] arm64: vdso: Force the vDSO to be linked as BTI when built " Mark Brown
2020-04-15 13:07 ` Mark Brown [this message]
2020-04-15 13:07 ` [PATCH 10/10] arm64: vdso: Map the VDSO text with guarded pages " Mark Brown

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