From: Boris Ostrovsky Date: Thu, 5 Nov 2015 18:56:35 +0000 (-0500) Subject: x86/mm: Skip the hypervisor range when walking PGD X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=f4e342c87776884f0309942a3880ca7e835239f9;p=deliverable%2Flinux.git x86/mm: Skip the hypervisor range when walking PGD The range between 0xffff800000000000 and 0xffff87ffffffffff is reserved for hypervisor and therefore we should not try to follow PGD's indexes corresponding to those addresses. While this has always been a problem, with the new W+X warning mechanism ptdump_walk_pgd_level_core() can now be called during boot, causing a PV Xen guest to crash. [ tglx: Replaced the macro with a readable inline ] Fixes: e1a58320a38d "x86/mm: Warn on W^X mappings" Reported-by: Sander Eikelenboom Signed-off-by: Boris Ostrovsky Cc: xen-devel@lists.xen.org Link: http://lkml.kernel.org/r/1446749795-27764-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index 1bf417e9cc13..a035c2aa7801 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -358,6 +358,21 @@ static void walk_pud_level(struct seq_file *m, struct pg_state *st, pgd_t addr, #define pgd_none(a) pud_none(__pud(pgd_val(a))) #endif +#ifdef CONFIG_X86_64 +static inline bool is_hypervisor_range(int idx) +{ + /* + * ffff800000000000 - ffff87ffffffffff is reserved for + * the hypervisor. + */ + return paravirt_enabled() && + (idx >= pgd_index(__PAGE_OFFSET) - 16) && + (idx < pgd_index(__PAGE_OFFSET)); +} +#else +static inline bool is_hypervisor_range(int idx) { return false; } +#endif + static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, bool checkwx) { @@ -381,7 +396,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, pgd_t *pgd, for (i = 0; i < PTRS_PER_PGD; i++) { st.current_address = normalize_addr(i * PGD_LEVEL_MULT); - if (!pgd_none(*start)) { + if (!pgd_none(*start) && !is_hypervisor_range(i)) { if (pgd_large(*start) || !pgd_present(*start)) { prot = pgd_flags(*start); note_page(m, &st, __pgprot(prot), 1);