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Message-ID: <tip-c1887159eb48ba40e775584cfb2a443962cf1a05@git.kernel.org>
Date: Tue, 25 Jun 2019 22:29:02 -0700
From: "tip-bot for Kirill A. Shutemov" <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: kirill.shutemov@...ux.intel.com, linux-kernel@...r.kernel.org,
mingo@...nel.org, peterz@...radead.org, kirill@...temov.name,
luto@...nel.org, tglx@...utronix.de, hpa@...or.com,
glider@...gle.com, dave.hansen@...ux.intel.com, bp@...en8.de
Subject: [tip:x86/urgent] x86/boot/64: Add missing fixup_pointer() for
next_early_pgt access
Commit-ID: c1887159eb48ba40e775584cfb2a443962cf1a05
Gitweb: https://git.kernel.org/tip/c1887159eb48ba40e775584cfb2a443962cf1a05
Author: Kirill A. Shutemov <kirill@...temov.name>
AuthorDate: Thu, 20 Jun 2019 14:24:22 +0300
Committer: Thomas Gleixner <tglx@...utronix.de>
CommitDate: Wed, 26 Jun 2019 07:25:09 +0200
x86/boot/64: Add missing fixup_pointer() for next_early_pgt access
__startup_64() uses fixup_pointer() to access global variables in a
position-independent fashion. Access to next_early_pgt was wrapped into the
helper, but one instance in the 5-level paging branch was missed.
GCC generates a R_X86_64_PC32 PC-relative relocation for the access which
doesn't trigger the issue, but Clang emmits a R_X86_64_32S which leads to
an invalid memory access and system reboot.
Fixes: 187e91fe5e91 ("x86/boot/64/clang: Use fixup_pointer() to access 'next_early_pgt'")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Alexander Potapenko <glider@...gle.com>
Link: https://lkml.kernel.org/r/20190620112422.29264-1-kirill.shutemov@linux.intel.com
---
arch/x86/kernel/head64.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index 7df5bce4e1be..29ffa495bd1c 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -184,7 +184,8 @@ unsigned long __head __startup_64(unsigned long physaddr,
pgtable_flags = _KERNPG_TABLE_NOENC + sme_get_me_mask();
if (la57) {
- p4d = fixup_pointer(early_dynamic_pgts[next_early_pgt++], physaddr);
+ p4d = fixup_pointer(early_dynamic_pgts[(*next_pgt_ptr)++],
+ physaddr);
i = (physaddr >> PGDIR_SHIFT) % PTRS_PER_PGD;
pgd[i + 0] = (pgdval_t)p4d + pgtable_flags;
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