arm64: vdso: Map the vDSO text with guarded pages when built for BTI (bf740a90) · Commits · 戴 / test

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> Link: https://lore.kernel.org/r/20200506195138.22086-12-broonie@kernel.org Signed-off-by:

Will Deacon <will@kernel.org>

arch/arm64/kernel/vdso.c

+5 −1

Original line number	Original line	Diff line number	Diff line
	@@ -142,6 +142,7 @@ static int __setup_additional_pages(enum arch_vdso_type arch_index,
	int uses_interp)		int uses_interp)
	{		{
	unsigned long vdso_base, vdso_text_len, vdso_mapping_len;		unsigned long vdso_base, vdso_text_len, vdso_mapping_len;
			unsigned long gp_flags = 0;
	void *ret;		void *ret;

	vdso_text_len = vdso_lookup[arch_index].vdso_pages << PAGE_SHIFT;		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))		if (IS_ERR(ret))
	goto up_fail;		goto up_fail;

			if (IS_ENABLED(CONFIG_ARM64_BTI_KERNEL) && system_supports_bti())
			gp_flags = VM_ARM64_BTI;

	vdso_base += PAGE_SIZE;		vdso_base += PAGE_SIZE;
	mm->context.vdso = (void *)vdso_base;		mm->context.vdso = (void *)vdso_base;
	ret = _install_special_mapping(mm, vdso_base, vdso_text_len,		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,		VM_MAYREAD\|VM_MAYWRITE\|VM_MAYEXEC,
	vdso_lookup[arch_index].cm);		vdso_lookup[arch_index].cm);
	if (IS_ERR(ret))		if (IS_ERR(ret))

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