Xen project Mailing List

Re: [Xen-devel] [PATCH] x86/xen: init %gs very early to avoid page faults with stack protector

From: Daniel Reichelt <hacking@xxxxxxxxxxxxxx>

Date: Sat, 14 Apr 2018 07:55:19 +0200

Delivery-date: Sun, 15 Apr 2018 13:06:59 +0000

List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

Hi, the patch v2 solved the issue for me only on amd64, i386 guests keep crashing with linux 4.15, 4.14 works fine. XEN host: - xen 4.8.3 - Debian stretch (tried with linux packages 4.14.0-0.bpo.3-amd64 and linux-image-4.15.0-0.bpo.2-amd64 - grub-pc package from buster (2.02+dfsg1-4) XEN guest: - Debian testing 32bit - booted via Debian's /usr/lib/grub-xen/grub-i386-xen.bin (buster, see XEN host) - linux-image-4.14.0-0.bpo.3-686-pae and earlier work fine --> linux-image-4.15.0-2-686-pae: boot aborts right after pvgrub launches the kernel, no output to the xen-guest console logfile. Whereas on the XEN host's serial console I see output similar to [1]: Try #1: --------8<----------------------------------- (XEN) d9v0: unhandled page fault (ec=0000) (XEN) Pagetable walk from 0000000000000014: (XEN) L4[0x000] = 000000028903b027 0000000000001e3b (XEN) L3[0x000] = 000000028904d027 0000000000001e4d (XEN) L2[0x000] = 000000028904e023 0000000000001e4e (XEN) L1[0x000] = 0000000000000000 ffffffffffffffff (XEN) domain_crash_sync called from entry.S: fault at ffff82d080239a68 entry.o#compat_create_bounce_frame+0xd9/0xf1 (XEN) Domain 9 (vcpu#0) crashed on cpu#8: (XEN) ----[ Xen-4.8.3 x86_64 debug=n Not tainted ]---- (XEN) CPU: 8 (XEN) RIP: e019:[<00000000c1031d39>] (XEN) RFLAGS: 0000000000000292 EM: 1 CONTEXT: pv guest (d9v0) (XEN) rax: 00000000c18a84c0 rbx: 00000000c162fce0 rcx: 0000000000000000 (XEN) rdx: 0000000000000000 rsi: 00000000c1815eec rdi: 00000000c1815f34 (XEN) rbp: 00000000c1815f10 rsp: 00000000c1815ecc r8: ffff83207b00fe58 (XEN) r9: ffff82d080197ea3 r10: 0000000080000008 r11: 0000000000000297 (XEN) r12: ffff83103ff30140 r13: ffff83103ff30148 r14: ffff83207b00ffff (XEN) r15: 0000000000000000 cr0: 000000008005003b cr4: 00000000003526e0 (XEN) cr3: 000000207b10c000 cr2: 0000000000000014 (XEN) fsb: 0000000000000000 gsb: 0000000000000000 gss: 0000000000000000 (XEN) ds: e021 es: e021 fs: e021 gs: e021 ss: e021 cs: e019 (XEN) Guest stack trace from esp=c1815ecc: (XEN) 00000000 c1031d39 0001e019 00010092 c18a84c0 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 ffffffff c1815f24 c18a84c0 c18a84c0 c1815f30 (XEN) c1815f34 c1815f50 c10328c7 c1815f3c c1815f38 c1815f40 0000302e 00000000 (XEN) 00000000 00000000 80000008 00000000 00000000 00000000 00000000 c1e38000 (XEN) c1a08000 c1815ffc c18c44c3 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 c1e38000 c1a08000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 -------->8----------------------------------- Try #2: --------8<----------------------------------- (XEN) d15v0: unhandled page fault (ec=0000) (XEN) Pagetable walk from 0000000000000014: (XEN) L4[0x000] = 000000028903b027 0000000000001e3b (XEN) L3[0x000] = 000000028904d027 0000000000001e4d (XEN) L2[0x000] = 000000028904e023 0000000000001e4e (XEN) L1[0x000] = 0000000000000000 ffffffffffffffff (XEN) domain_crash_sync called from entry.S: fault at ffff82d080239a68 entry.o#compat_create_bounce_frame+0xd9/0xf1 (XEN) Domain 15 (vcpu#0) crashed on cpu#7: (XEN) ----[ Xen-4.8.3 x86_64 debug=n Not tainted ]---- (XEN) CPU: 7 (XEN) RIP: e019:[<00000000c1031d39>] (XEN) RFLAGS: 0000000000000292 EM: 1 CONTEXT: pv guest (d15v0) (XEN) rax: 00000000c18a84c0 rbx: 00000000c162fce0 rcx: 0000000000000000 (XEN) rdx: 0000000000000000 rsi: 00000000c1815eec rdi: 00000000c1815f34 (XEN) rbp: 00000000c1815f10 rsp: 00000000c1815ecc r8: ffff83103ff3fe58 (XEN) r9: ffff82d080197ea3 r10: 0000000080000008 r11: 0000000000000297 (XEN) r12: ffff83103ff42140 r13: ffff83103ff42148 r14: ffff83103ff3ffff (XEN) r15: 0000000000000000 cr0: 000000008005003b cr4: 00000000003526e0 (XEN) cr3: 000000207b103000 cr2: 0000000000000014 (XEN) fsb: 0000000000000000 gsb: 0000000000000000 gss: 0000000000000000 (XEN) ds: e021 es: e021 fs: e021 gs: e021 ss: e021 cs: e019 (XEN) Guest stack trace from esp=c1815ecc: (XEN) 00000000 c1031d39 0001e019 00010092 c18a84c0 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 ffffffff c1815f24 c18a84c0 c18a84c0 c1815f30 (XEN) c1815f34 c1815f50 c10328c7 c1815f3c c1815f38 c1815f40 0000302e 00000000 (XEN) 00000000 00000000 80000008 00000000 00000000 00000000 00000000 c1e38000 (XEN) c1a08000 c1815ffc c18c44c3 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 c1e38000 c1a08000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 (XEN) 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 -------->8----------------------------------- Let me know if you need more info. Thanks! Daniel (please CC me since I'm not subscribed to the list) [1] https://www.mail-archive.com/grub-devel@xxxxxxx/msg26612.html

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