From: Christopher Lameter <cl@linux.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Kate Stewart" <kstewart@linuxfoundation.org>,
"Nicolas Pitre" <nicolas.pitre@linaro.org>,
"Michal Hocko" <mhocko@suse.com>,
"Sergey Senozhatsky" <sergey.senozhatsky.work@gmail.com>,
"Petr Mladek" <pmladek@suse.com>,
"Len Brown" <len.brown@intel.com>,
"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Christopher Li" <sparse@chrisli.org>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
x86@kernel.org, "Dominik Brodowski" <linux@dominikbrodowski.net>,
linux-kernel@vger.kernel.org,
"Masahiro Yamada" <yamada.masahiro@socionext.com>,
"Pavel Machek" <pavel@ucw.cz>, "H . Peter Anvin" <hpa@zytor.com>,
kernel-hardening@lists.openwall.com,
"Jiri Slaby" <jslaby@suse.cz>,
"Alok Kataria" <akataria@vmware.com>,
linux-doc@vger.kernel.org, linux-arch@vger.kernel.org,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"Baoquan He" <bhe@redhat.com>, "Jonathan Corbet" <corbet@lwn.net>,
"Joerg Roedel" <joro@8bytes.org>
Subject: Re: [PATCH v2 06/27] x86/entry/64: Adapt assembly for PIE support
Date: Wed, 14 Mar 2018 10:54:58 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.20.1803141051210.14471__39395.64925754$1521042834$gmane$org@nuc-kabylake> (raw)
In-Reply-To: <20180314102951.GQ4043@hirez.programming.kicks-ass.net>
On Wed, 14 Mar 2018, Peter Zijlstra wrote:
> On Tue, Mar 13, 2018 at 01:59:24PM -0700, Thomas Garnier wrote:
> > @@ -1576,7 +1578,9 @@ first_nmi:
> > addq $8, (%rsp) /* Fix up RSP */
> > pushfq /* RFLAGS */
> > pushq $__KERNEL_CS /* CS */
> > - pushq $1f /* RIP */
> > + pushq %rax /* Support Position Independent Code */
> > + leaq 1f(%rip), %rax /* RIP */
> > + xchgq %rax, (%rsp) /* Restore RAX, put 1f */
> > iretq /* continues at repeat_nmi below */
> > UNWIND_HINT_IRET_REGS
> > 1:
>
> Urgh, xchg with a memop has an implicit LOCK prefix.
this_cpu_xchg uses no lock cmpxchg as a replacement to reduce latency.
From linux/arch/x86/include/asm/percpu.h
/*
* xchg is implemented using cmpxchg without a lock prefix. xchg is
* expensive due to the implied lock prefix. The processor cannot prefetch
* cachelines if xchg is used.
*/
#define percpu_xchg_op(var, nval) \
({ \
typeof(var) pxo_ret__; \
typeof(var) pxo_new__ = (nval); \
switch (sizeof(var)) { \
case 1: \
asm("\n\tmov "__percpu_arg(1)",%%al" \
"\n1:\tcmpxchgb %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "q" (pxo_new__) \
: "memory"); \
break; \
case 2: \
asm("\n\tmov "__percpu_arg(1)",%%ax" \
"\n1:\tcmpxchgw %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
case 4: \
asm("\n\tmov "__percpu_arg(1)",%%eax" \
"\n1:\tcmpxchgl %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
case 8: \
asm("\n\tmov "__percpu_arg(1)",%%rax" \
"\n1:\tcmpxchgq %2, "__percpu_arg(1) \
"\n\tjnz 1b" \
: "=&a" (pxo_ret__), "+m" (var) \
: "r" (pxo_new__) \
: "memory"); \
break; \
default: __bad_percpu_size(); \
} \
pxo_ret__; \
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next prev parent reply other threads:[~2018-03-14 15:55 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-13 20:59 [PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 01/27] x86/crypto: Adapt assembly for PIE support Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 02/27] x86: Use symbol name on bug table " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 03/27] x86: Use symbol name in jump " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 04/27] x86: Add macro to get symbol address " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 05/27] x86: relocate_kernel - Adapt assembly " Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 06/27] x86/entry/64: " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-14 10:29 ` Peter Zijlstra
2018-03-14 10:29 ` Peter Zijlstra
2018-03-14 10:29 ` Peter Zijlstra
2018-03-14 15:54 ` Christopher Lameter
2018-03-14 15:54 ` Christopher Lameter
2018-03-14 15:54 ` Christopher Lameter
2018-03-14 15:54 ` Christopher Lameter
2018-03-14 17:09 ` Thomas Garnier via Virtualization
2018-03-14 17:09 ` Thomas Garnier via Virtualization
2018-03-14 17:09 ` Thomas Garnier
2018-03-14 17:09 ` Thomas Garnier
2018-03-15 10:18 ` Paolo Bonzini
2018-03-15 10:18 ` Paolo Bonzini
2018-03-15 10:18 ` Paolo Bonzini
2018-03-14 15:54 ` Christopher Lameter [this message]
2018-03-14 10:29 ` Peter Zijlstra
2018-03-13 20:59 ` [PATCH v2 07/27] x86: pm-trace - " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 08/27] x86/CPU: " Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 09/27] x86/acpi: " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 10/27] x86/boot/64: " Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 11/27] x86/power/64: " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 12/27] x86/paravirt: " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 13/27] x86/boot/64: Build head64.c as mcmodel large when PIE is enabled Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 14/27] x86/percpu: Adapt percpu for PIE support Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 15/27] compiler: Option to default to hidden symbols Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 16/27] compiler: Option to add PROVIDE_HIDDEN replacement for weak symbols Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 17/27] x86/relocs: Handle PIE relocations Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 18/27] xen: Adapt assembly for PIE support Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 19/27] kvm: " Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 20/27] x86: Support global stack cookie Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 21/27] x86/ftrace: Adapt function tracing for PIE support Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-14 10:35 ` Peter Zijlstra
2018-03-14 10:35 ` Peter Zijlstra
2018-03-14 10:35 ` Peter Zijlstra
2018-03-14 10:35 ` Peter Zijlstra
2018-03-13 20:59 ` [PATCH v2 22/27] x86/modules: Add option to start module section after kernel Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 23/27] x86/modules: Adapt module loading for PIE support Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 24/27] x86/mm: Make the x86 GOT read-only Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 25/27] x86/pie: Add option to build the kernel as PIE Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` [PATCH v2 26/27] x86/relocs: Add option to generate 64-bit relocations Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier via Virtualization
2018-03-13 20:59 ` [PATCH v2 27/27] x86/kaslr: Add option to extend KASLR range from 1GB to 3GB Thomas Garnier via Virtualization
2018-03-13 20:59 ` Thomas Garnier
2018-03-13 20:59 ` Thomas Garnier
2018-03-15 8:48 ` [PATCH v2 00/27] x86: PIE support and option to extend KASLR randomization Pavel Machek
2018-03-15 8:48 ` Pavel Machek
2018-03-15 8:48 ` Pavel Machek
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