diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0006-kaiser-do-not-set-_PAGE_NX-on-pgd_none.patch')
-rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0006-kaiser-do-not-set-_PAGE_NX-on-pgd_none.patch | 212 |
1 files changed, 0 insertions, 212 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-kaiser-do-not-set-_PAGE_NX-on-pgd_none.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-kaiser-do-not-set-_PAGE_NX-on-pgd_none.patch deleted file mode 100644 index 973bd7f6..00000000 --- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0006-kaiser-do-not-set-_PAGE_NX-on-pgd_none.patch +++ /dev/null @@ -1,212 +0,0 @@ -From 495d2eaaa7862a3ad27140ad0876ae931ddd5e80 Mon Sep 17 00:00:00 2001 -From: Hugh Dickins <hughd@google.com> -Date: Tue, 5 Sep 2017 12:05:01 -0700 -Subject: [PATCH 006/103] kaiser: do not set _PAGE_NX on pgd_none - -native_pgd_clear() uses native_set_pgd(), so native_set_pgd() must -avoid setting the _PAGE_NX bit on an otherwise pgd_none() entry: -usually that just generated a warning on exit, but sometimes -more mysterious and damaging failures (our production machines -could not complete booting). - -The original fix to this just avoided adding _PAGE_NX to -an empty entry; but eventually more problems surfaced with kexec, -and EFI mapping expected to be a problem too. So now instead -change native_set_pgd() to update shadow only if _PAGE_USER: - -A few places (kernel/machine_kexec_64.c, platform/efi/efi_64.c for sure) -use set_pgd() to set up a temporary internal virtual address space, with -physical pages remapped at what Kaiser regards as userspace addresses: -Kaiser then assumes a shadow pgd follows, which it will try to corrupt. - -This appears to be responsible for the recent kexec and kdump failures; -though it's unclear how those did not manifest as a problem before. -Ah, the shadow pgd will only be assumed to "follow" if the requested -pgd is on an even-numbered page: so I suppose it was going wrong 50% -of the time all along. - -What we need is a flag to set_pgd(), to tell it we're dealing with -userspace. Er, isn't that what the pgd's _PAGE_USER bit is saying? -Add a test for that. But we cannot do the same for pgd_clear() -(which may be called to clear corrupted entries - set aside the -question of "corrupt in which pgd?" until later), so there just -rely on pgd_clear() not being called in the problematic cases - -with a WARN_ON_ONCE() which should fire half the time if it is. - -But this is getting too big for an inline function: move it into -arch/x86/mm/kaiser.c (which then demands a boot/compressed mod); -and de-void and de-space native_get_shadow/normal_pgd() while here. - -Also make an unnecessary change to KASLR's init_trampoline(): it was -using set_pgd() to assign a pgd-value to a global variable (not in a -pg directory page), which was rather scary given Kaiser's previous -set_pgd() implementation: not a problem now, but too scary to leave -as was, it could easily blow up if we have to change set_pgd() again. - -Signed-off-by: Hugh Dickins <hughd@google.com> -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - arch/x86/boot/compressed/misc.h | 1 + - arch/x86/include/asm/pgtable_64.h | 51 ++++++++++----------------------------- - arch/x86/mm/kaiser.c | 42 ++++++++++++++++++++++++++++++++ - arch/x86/mm/kaslr.c | 4 +-- - 4 files changed, 58 insertions(+), 40 deletions(-) - -diff --git a/arch/x86/boot/compressed/misc.h b/arch/x86/boot/compressed/misc.h -index 1c8355e..cd80024 100644 ---- a/arch/x86/boot/compressed/misc.h -+++ b/arch/x86/boot/compressed/misc.h -@@ -9,6 +9,7 @@ - */ - #undef CONFIG_PARAVIRT - #undef CONFIG_PARAVIRT_SPINLOCKS -+#undef CONFIG_KAISER - #undef CONFIG_KASAN - - #include <linux/linkage.h> -diff --git a/arch/x86/include/asm/pgtable_64.h b/arch/x86/include/asm/pgtable_64.h -index 000265c..177caf3 100644 ---- a/arch/x86/include/asm/pgtable_64.h -+++ b/arch/x86/include/asm/pgtable_64.h -@@ -107,61 +107,36 @@ static inline void native_pud_clear(pud_t *pud) - } - - #ifdef CONFIG_KAISER --static inline pgd_t * native_get_shadow_pgd(pgd_t *pgdp) -+extern pgd_t kaiser_set_shadow_pgd(pgd_t *pgdp, pgd_t pgd); -+ -+static inline pgd_t *native_get_shadow_pgd(pgd_t *pgdp) - { -- return (pgd_t *)(void*)((unsigned long)(void*)pgdp | (unsigned long)PAGE_SIZE); -+ return (pgd_t *)((unsigned long)pgdp | (unsigned long)PAGE_SIZE); - } - --static inline pgd_t * native_get_normal_pgd(pgd_t *pgdp) -+static inline pgd_t *native_get_normal_pgd(pgd_t *pgdp) - { -- return (pgd_t *)(void*)((unsigned long)(void*)pgdp & ~(unsigned long)PAGE_SIZE); -+ return (pgd_t *)((unsigned long)pgdp & ~(unsigned long)PAGE_SIZE); - } - #else --static inline pgd_t * native_get_shadow_pgd(pgd_t *pgdp) -+static inline pgd_t kaiser_set_shadow_pgd(pgd_t *pgdp, pgd_t pgd) -+{ -+ return pgd; -+} -+static inline pgd_t *native_get_shadow_pgd(pgd_t *pgdp) - { - BUILD_BUG_ON(1); - return NULL; - } --static inline pgd_t * native_get_normal_pgd(pgd_t *pgdp) -+static inline pgd_t *native_get_normal_pgd(pgd_t *pgdp) - { - return pgdp; - } - #endif /* CONFIG_KAISER */ - --/* -- * Page table pages are page-aligned. The lower half of the top -- * level is used for userspace and the top half for the kernel. -- * This returns true for user pages that need to get copied into -- * both the user and kernel copies of the page tables, and false -- * for kernel pages that should only be in the kernel copy. -- */ --static inline bool is_userspace_pgd(void *__ptr) --{ -- unsigned long ptr = (unsigned long)__ptr; -- -- return ((ptr % PAGE_SIZE) < (PAGE_SIZE / 2)); --} -- - static inline void native_set_pgd(pgd_t *pgdp, pgd_t pgd) - { --#ifdef CONFIG_KAISER -- pteval_t extra_kern_pgd_flags = 0; -- /* Do we need to also populate the shadow pgd? */ -- if (is_userspace_pgd(pgdp)) { -- native_get_shadow_pgd(pgdp)->pgd = pgd.pgd; -- /* -- * Even if the entry is *mapping* userspace, ensure -- * that userspace can not use it. This way, if we -- * get out to userspace running on the kernel CR3, -- * userspace will crash instead of running. -- */ -- extra_kern_pgd_flags = _PAGE_NX; -- } -- pgdp->pgd = pgd.pgd; -- pgdp->pgd |= extra_kern_pgd_flags; --#else /* CONFIG_KAISER */ -- *pgdp = pgd; --#endif -+ *pgdp = kaiser_set_shadow_pgd(pgdp, pgd); - } - - static inline void native_pgd_clear(pgd_t *pgd) -diff --git a/arch/x86/mm/kaiser.c b/arch/x86/mm/kaiser.c -index 7270a29..8d6061c 100644 ---- a/arch/x86/mm/kaiser.c -+++ b/arch/x86/mm/kaiser.c -@@ -302,4 +302,46 @@ void kaiser_remove_mapping(unsigned long start, unsigned long size) - unmap_pud_range_nofree(pgd, addr, end); - } - } -+ -+/* -+ * Page table pages are page-aligned. The lower half of the top -+ * level is used for userspace and the top half for the kernel. -+ * This returns true for user pages that need to get copied into -+ * both the user and kernel copies of the page tables, and false -+ * for kernel pages that should only be in the kernel copy. -+ */ -+static inline bool is_userspace_pgd(pgd_t *pgdp) -+{ -+ return ((unsigned long)pgdp % PAGE_SIZE) < (PAGE_SIZE / 2); -+} -+ -+pgd_t kaiser_set_shadow_pgd(pgd_t *pgdp, pgd_t pgd) -+{ -+ /* -+ * Do we need to also populate the shadow pgd? Check _PAGE_USER to -+ * skip cases like kexec and EFI which make temporary low mappings. -+ */ -+ if (pgd.pgd & _PAGE_USER) { -+ if (is_userspace_pgd(pgdp)) { -+ native_get_shadow_pgd(pgdp)->pgd = pgd.pgd; -+ /* -+ * Even if the entry is *mapping* userspace, ensure -+ * that userspace can not use it. This way, if we -+ * get out to userspace running on the kernel CR3, -+ * userspace will crash instead of running. -+ */ -+ pgd.pgd |= _PAGE_NX; -+ } -+ } else if (!pgd.pgd) { -+ /* -+ * pgd_clear() cannot check _PAGE_USER, and is even used to -+ * clear corrupted pgd entries: so just rely on cases like -+ * kexec and EFI never to be using pgd_clear(). -+ */ -+ if (!WARN_ON_ONCE((unsigned long)pgdp & PAGE_SIZE) && -+ is_userspace_pgd(pgdp)) -+ native_get_shadow_pgd(pgdp)->pgd = pgd.pgd; -+ } -+ return pgd; -+} - #endif /* CONFIG_KAISER */ -diff --git a/arch/x86/mm/kaslr.c b/arch/x86/mm/kaslr.c -index aed2064..9284ec1 100644 ---- a/arch/x86/mm/kaslr.c -+++ b/arch/x86/mm/kaslr.c -@@ -189,6 +189,6 @@ void __meminit init_trampoline(void) - *pud_tramp = *pud; - } - -- set_pgd(&trampoline_pgd_entry, -- __pgd(_KERNPG_TABLE | __pa(pud_page_tramp))); -+ /* Avoid set_pgd(), in case it's complicated by CONFIG_KAISER */ -+ trampoline_pgd_entry = __pgd(_KERNPG_TABLE | __pa(pud_page_tramp)); - } --- -2.7.4 - |