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SubjectRe: [PATCH v1 2/4] x86/xen: add basic KASAN support for PV kernel
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On 08.01.20 16:20, Sergey Dyasli wrote:
> This enables to use Outline instrumentation for Xen PV kernels.
>
> KASAN_INLINE and KASAN_VMALLOC options currently lead to boot crashes
> and hence disabled.
>
> Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com>
> ---
> RFC --> v1:
> - New functions with declarations in xen/xen-ops.h
> - Fixed the issue with free_kernel_image_pages() with the help of
> xen_pv_kasan_unpin_pgd()
> ---
> arch/x86/mm/kasan_init_64.c | 12 ++++++++++++
> arch/x86/xen/Makefile | 7 +++++++
> arch/x86/xen/enlighten_pv.c | 3 +++
> arch/x86/xen/mmu_pv.c | 39 +++++++++++++++++++++++++++++++++++++
> drivers/xen/Makefile | 2 ++
> include/xen/xen-ops.h | 4 ++++
> kernel/Makefile | 2 ++
> lib/Kconfig.kasan | 3 ++-
> 8 files changed, 71 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/kasan_init_64.c b/arch/x86/mm/kasan_init_64.c
> index cf5bc37c90ac..902a6a152d33 100644
> --- a/arch/x86/mm/kasan_init_64.c
> +++ b/arch/x86/mm/kasan_init_64.c
> @@ -13,6 +13,9 @@
> #include <linux/sched/task.h>
> #include <linux/vmalloc.h>
>
> +#include <xen/xen.h>
> +#include <xen/xen-ops.h>
> +
> #include <asm/e820/types.h>
> #include <asm/pgalloc.h>
> #include <asm/tlbflush.h>
> @@ -332,6 +335,11 @@ void __init kasan_early_init(void)
> for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
> kasan_early_shadow_p4d[i] = __p4d(p4d_val);
>
> + if (xen_pv_domain()) {
> + pgd_t *pv_top_pgt = xen_pv_kasan_early_init();

You are breaking the build with CONFIG_XEN_PV undefined here.

> + kasan_map_early_shadow(pv_top_pgt);
> + }
> +
> kasan_map_early_shadow(early_top_pgt);
> kasan_map_early_shadow(init_top_pgt);
> }
> @@ -369,6 +377,8 @@ void __init kasan_init(void)
> __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
> }
>
> + xen_pv_kasan_pin_pgd(early_top_pgt);

Same here (and below). For the pin/unpin variants I'd rather have
an inline wrapper containing the "if (xen_pv_domain())" in xen-ops.h
which can easily contain the needed #ifdef CONFIG_XEN_PV.


Juergen

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