From patchwork Thu May 21 15:23:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Price X-Patchwork-Id: 11563249 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 8E572739 for ; Thu, 21 May 2020 15:23:25 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5B24A20872 for ; Thu, 21 May 2020 15:23:25 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5B24A20872 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id D73388000C; Thu, 21 May 2020 11:23:19 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id CFC6B8000A; Thu, 21 May 2020 11:23:19 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id B7BC58000C; Thu, 21 May 2020 11:23:19 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0127.hostedemail.com [216.40.44.127]) by kanga.kvack.org (Postfix) with ESMTP id 977C38000A for ; Thu, 21 May 2020 11:23:19 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 58CB58248047 for ; Thu, 21 May 2020 15:23:19 +0000 (UTC) X-FDA: 76841094918.02.death14_5724b85f52106 X-Spam-Summary: 2,0,0,1d502f19d6036ad7,d41d8cd98f00b204,steven.price@arm.com,,RULES_HIT:41:69:355:379:541:800:960:973:988:989:1260:1261:1311:1314:1345:1359:1437:1515:1535:1544:1605:1711:1730:1747:1777:1792:1981:2194:2198:2199:2200:2393:2553:2559:2562:2730:2895:2901:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:3874:4117:4321:4605:5007:6119:6261:7903:8634:9592:10004:11026:11473:11658:11914:12043:12048:12296:12297:12438:12517:12519:12555:12679:12683:12895:12986:13161:13180:13221:13229:13894:14096:14181:14394:14721:21080:21433:21451:21611:21627:21990:30012:30045:30054:30070:30090,0,RBL:217.140.110.172:@arm.com:.lbl8.mailshell.net-62.2.0.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none X-HE-Tag: death14_5724b85f52106 X-Filterd-Recvd-Size: 6227 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Thu, 21 May 2020 15:23:18 +0000 (UTC) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id DE95B1042; Thu, 21 May 2020 08:23:17 -0700 (PDT) Received: from e112269-lin.arm.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 3F5253F305; Thu, 21 May 2020 08:23:16 -0700 (PDT) From: Steven Price To: Andrew Morton , Andy Lutomirski , Borislav Petkov , Dave Hansen , Ingo Molnar , Peter Zijlstra , Thomas Gleixner , x86@kernel.org, Jan Beulich Cc: Steven Price , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 1/2] x86: mm: ptdump: Calculate effective permissions correctly Date: Thu, 21 May 2020 16:23:07 +0100 Message-Id: <20200521152308.33096-2-steven.price@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200521152308.33096-1-steven.price@arm.com> References: <20200521152308.33096-1-steven.price@arm.com> MIME-Version: 1.0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: By switching the x86 page table dump code to use the generic code the effective permissions are no longer calculated correctly because the note_page() function is only called for *leaf* entries. To calculate the actual effective permissions it is necessary to observe the full hierarchy of the page tree. Introduce a new callback for ptdump which is called for every entry and can therefore update the prot_levels array correctly. note_page() can then simply access the appropriate element in the array. Reported-by: Jan Beulich Fixes: 2ae27137b2db ("x86: mm: convert dump_pagetables to use walk_page_range") Signed-off-by: Steven Price Tested-by: Jan Beulich --- arch/x86/mm/dump_pagetables.c | 31 +++++++++++++++++++------------ include/linux/ptdump.h | 1 + mm/ptdump.c | 17 ++++++++++++++++- 3 files changed, 36 insertions(+), 13 deletions(-) diff --git a/arch/x86/mm/dump_pagetables.c b/arch/x86/mm/dump_pagetables.c index 69309cd56fdf..199bbb7fbd79 100644 --- a/arch/x86/mm/dump_pagetables.c +++ b/arch/x86/mm/dump_pagetables.c @@ -249,10 +249,22 @@ static void note_wx(struct pg_state *st, unsigned long addr) (void *)st->start_address); } -static inline pgprotval_t effective_prot(pgprotval_t prot1, pgprotval_t prot2) +static void effective_prot(struct ptdump_state *pt_st, int level, u64 val) { - return (prot1 & prot2 & (_PAGE_USER | _PAGE_RW)) | - ((prot1 | prot2) & _PAGE_NX); + struct pg_state *st = container_of(pt_st, struct pg_state, ptdump); + pgprotval_t prot = val & PTE_FLAGS_MASK; + pgprotval_t effective; + + if (level > 0) { + pgprotval_t higher_prot = st->prot_levels[level - 1]; + + effective = (higher_prot & prot & (_PAGE_USER | _PAGE_RW)) | + ((higher_prot | prot) & _PAGE_NX); + } else { + effective = prot; + } + + st->prot_levels[level] = effective; } /* @@ -270,16 +282,10 @@ static void note_page(struct ptdump_state *pt_st, unsigned long addr, int level, struct seq_file *m = st->seq; new_prot = val & PTE_FLAGS_MASK; + new_eff = st->prot_levels[level]; - if (level > 0) { - new_eff = effective_prot(st->prot_levels[level - 1], - new_prot); - } else { - new_eff = new_prot; - } - - if (level >= 0) - st->prot_levels[level] = new_eff; + if (!val) + new_eff = 0; /* * If we have a "break" in the series, we need to flush the state that @@ -374,6 +380,7 @@ static void ptdump_walk_pgd_level_core(struct seq_file *m, struct pg_state st = { .ptdump = { .note_page = note_page, + .effective_prot = effective_prot, .range = ptdump_ranges }, .level = -1, diff --git a/include/linux/ptdump.h b/include/linux/ptdump.h index a67065c403c3..ac01502763bf 100644 --- a/include/linux/ptdump.h +++ b/include/linux/ptdump.h @@ -14,6 +14,7 @@ struct ptdump_state { /* level is 0:PGD to 4:PTE, or -1 if unknown */ void (*note_page)(struct ptdump_state *st, unsigned long addr, int level, unsigned long val); + void (*effective_prot)(struct ptdump_state *st, int level, u64 val); const struct ptdump_range *range; }; diff --git a/mm/ptdump.c b/mm/ptdump.c index 26208d0d03b7..f4ce916f5602 100644 --- a/mm/ptdump.c +++ b/mm/ptdump.c @@ -36,6 +36,9 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr, return note_kasan_page_table(walk, addr); #endif + if (st->effective_prot) + st->effective_prot(st, 0, pgd_val(val)); + if (pgd_leaf(val)) st->note_page(st, addr, 0, pgd_val(val)); @@ -53,6 +56,9 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr, return note_kasan_page_table(walk, addr); #endif + if (st->effective_prot) + st->effective_prot(st, 1, p4d_val(val)); + if (p4d_leaf(val)) st->note_page(st, addr, 1, p4d_val(val)); @@ -70,6 +76,9 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr, return note_kasan_page_table(walk, addr); #endif + if (st->effective_prot) + st->effective_prot(st, 2, pud_val(val)); + if (pud_leaf(val)) st->note_page(st, addr, 2, pud_val(val)); @@ -87,6 +96,8 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr, return note_kasan_page_table(walk, addr); #endif + if (st->effective_prot) + st->effective_prot(st, 3, pmd_val(val)); if (pmd_leaf(val)) st->note_page(st, addr, 3, pmd_val(val)); @@ -97,8 +108,12 @@ static int ptdump_pte_entry(pte_t *pte, unsigned long addr, unsigned long next, struct mm_walk *walk) { struct ptdump_state *st = walk->private; + pte_t val = READ_ONCE(*pte); + + if (st->effective_prot) + st->effective_prot(st, 4, pte_val(val)); - st->note_page(st, addr, 4, pte_val(READ_ONCE(*pte))); + st->note_page(st, addr, 4, pte_val(val)); return 0; }