diff mbox series

[v3,11/11] arm64: vdso: Map the vDSO text with guarded pages when built for BTI

Message ID 20200506195138.22086-12-broonie@kernel.org (mailing list archive)
State New, archived
Headers show
Series arm64: BTI kernel and vDSO support | expand

Commit Message

Mark Brown May 6, 2020, 7:51 p.m. UTC 
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>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
---
 arch/arm64/kernel/vdso.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/arm64/kernel/vdso.c b/arch/arm64/kernel/vdso.c
index 033a48f30dbb..3b0289d5cccb 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))