From: Lai Jiangshan <jiangshanlai@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Lai Jiangshan <laijs@linux.alibaba.com>,
Andy Lutomirski <luto@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Vincenzo Frascino <vincenzo.frascino@arm.com>,
Joerg Roedel <jroedel@suse.de>,
Ricardo Neri <ricardo.neri-calderon@linux.intel.com>,
Reinette Chatre <reinette.chatre@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Gabriel Krisman Bertazi <krisman@collabora.com>,
Kees Cook <keescook@chromium.org>,
Frederic Weisbecker <frederic@kernel.org>,
Jens Axboe <axboe@kernel.dk>,
Arvind Sankar <nivedita@alum.mit.edu>,
Brian Gerst <brgerst@gmail.com>, Ard Biesheuvel <ardb@kernel.org>,
Andi Kleen <ak@linux.intel.com>, Mike Rapoport <rppt@kernel.org>,
Mike Hommey <mh@glandium.org>,
Mark Gross <mgross@linux.intel.com>,
Fenghua Yu <fenghua.yu@intel.com>,
Tony Luck <tony.luck@intel.com>,
Anthony Steinhauser <asteinhauser@google.com>,
Jay Lang <jaytlang@mit.edu>,
"Chang S. Bae" <chang.seok.bae@intel.com>
Subject: [PATCH V3 3/6] x86_32/sysenter: switch to the task stack without emptying the entry stack
Date: Thu, 28 Jan 2021 00:32:19 +0800 [thread overview]
Message-ID: <20210127163231.12709-4-jiangshanlai@gmail.com> (raw)
In-Reply-To: <20210127163231.12709-1-jiangshanlai@gmail.com>
From: Lai Jiangshan <laijs@linux.alibaba.com>
Like the way x86_64 uses the "old" stack, we can save the entry stack
pointer to a register and switch to the task stack. So that we have
space on the "old" stack to save more things or scratch registers.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
arch/x86/entry/entry_32.S | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S
index 3b4d1a63d1f0..3e693db0963d 100644
--- a/arch/x86/entry/entry_32.S
+++ b/arch/x86/entry/entry_32.S
@@ -905,19 +905,18 @@ SYM_FUNC_START(entry_SYSENTER_32)
pushl %eax
BUG_IF_WRONG_CR3 no_user_check=1
SWITCH_TO_KERNEL_CR3 scratch_reg=%eax
- popl %eax
- popfl
- /* Stack empty again, switch to task stack */
- movl TSS_entry2task_stack(%esp), %esp
+ /* Switch to task stack */
+ movl %esp, %eax
+ movl (2*4+TSS_entry2task_stack)(%esp), %esp
.Lsysenter_past_esp:
pushl $__USER_DS /* pt_regs->ss */
pushl $0 /* pt_regs->sp (placeholder) */
- pushfl /* pt_regs->flags (except IF = 0) */
+ pushl %ss:4(%eax) /* pt_regs->flags (except IF = 0) */
pushl $__USER_CS /* pt_regs->cs */
pushl $0 /* pt_regs->ip = 0 (placeholder) */
- pushl %eax /* pt_regs->orig_ax */
+ pushl %ss:(%eax) /* pt_regs->orig_ax */
SAVE_ALL pt_regs_ax=$-ENOSYS /* save rest, stack already switched */
/*
--
2.19.1.6.gb485710b
next prev parent reply other threads:[~2021-01-27 15:55 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-27 16:32 [PATCH V3 0/6] x86: don't abuse tss.sp1 Lai Jiangshan
2021-01-27 16:32 ` [PATCH V3 1/6] x86_64: move cpu_current_top_of_stack out of TSS Lai Jiangshan
2021-02-04 16:46 ` Borislav Petkov
2021-01-27 16:32 ` [PATCH V3 2/6] x86_32: use percpu instead of offset-calculation to get thread.sp0 when SWITCH_TO_KERNEL_STACK Lai Jiangshan
2021-02-08 19:21 ` Borislav Petkov
2021-01-27 16:32 ` Lai Jiangshan [this message]
2021-01-27 16:32 ` [PATCH V3 4/6] x86_32/sysenter: restore %fs before switching stack Lai Jiangshan
2021-01-27 16:32 ` [PATCH V3 5/6] x86_32/sysenter: use percpu to get thread.sp0 when sysenter Lai Jiangshan
2021-01-27 16:32 ` [PATCH V3 6/6] x86_32: use cpu_current_thread_sp0 instead of cpu_tss_rw.x86_tss.sp1 Lai Jiangshan
[not found] ` <CAJhGHyA1U9M2Lv_=Wa2NPzBNevZKOrLaG1FDwbmySMOR_x_GRQ@mail.gmail.com>
2021-01-29 16:43 ` [PATCH V3 0/6] x86: don't abuse tss.sp1 Borislav Petkov
2021-01-30 2:53 ` Lai Jiangshan
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