From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELsdSToNTXxASODtc7hglh3AdrPxR+8DOZwx9XQNCTY9UsGBrtA3lmHGsAWTCiZNH3Vjqkzm ARC-Seal: i=1; a=rsa-sha256; t=1520245570; cv=none; d=google.com; s=arc-20160816; b=H+1jkkfHU5EihlaoLZUkOKQbAVKjBBXAd4Q3thFjooVbpGN1AXCILoT7RG2Qwugwra OGMz9j3/Pag/wk6Np1MgJ8lDg/+fPAExtrL9O6fI3F1KLFP08Cfcr/jwYGUrbdCABdbn 4kvQ2dmBygxh2mPOej1mqWYsC9Fd12jeVqjYajcBVchqcZUts45VgS1UTffjm6io6cO+ y4r2Exwd3cZddQL/zHUQ+bvRwFU/CE0rEdWwaVfFwF5VBXUIhzt0vI59xJJJNU2nTV0j QS/OlWtraDaYuHEizr+2MiQTCX4sNUMziBfL+/x8LD6DkoonrHDuV4s7ANqE5misS9uC XQwg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature:arc-authentication-results; bh=NTVb4LONHnLz6w99SoQtjWWuv+4gRfgau5jr8PemZlw=; b=Dx21zZJWsWkF8FsAgEAcgh/12E7XLkJuJT2AlhvuUZCkveavaOE1FpqG6EJzCbiVoH jMbH5GyV0wzh1NNxI0iOiXZy2Dx3ki3wc+RevKC9Gqec2FwE26R4t3BFIco0QRJF9lyY W1bhQobhETMvX+coRvnm+raAXgz2pHFoVpvmpxsDZ5qg4TOLThhqNVdlBxGHIC24d6a6 sJcJypsad425OGS2hJPMAbDLuf3MoiMqoq7cGA0ReB8bwBzA4GlvvbdOsMmzC8lIst0J IL4iE/VhDX0GwQetR8nCvAoTHAq+mSP7Oq2MtURbtGFmWQiq4deo+R8sYLwpG5nAa6Dk SchQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=mWC+RCI+; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=mWC+RCI+; spf=pass (google.com: domain of joro@8bytes.org designates 81.169.241.247 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org From: Joerg Roedel To: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" Cc: x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , Pavel Machek , jroedel@suse.de, joro@8bytes.org Subject: [PATCH 03/34] x86/entry/32: Load task stack from x86_tss.sp1 in SYSENTER handler Date: Mon, 5 Mar 2018 11:25:32 +0100 Message-Id: <1520245563-8444-4-git-send-email-joro@8bytes.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1520245563-8444-1-git-send-email-joro@8bytes.org> References: <1520245563-8444-1-git-send-email-joro@8bytes.org> X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594093019795549964?= X-GMAIL-MSGID: =?utf-8?q?1594093019795549964?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: From: Joerg Roedel We want x86_tss.sp0 point to the entry stack later to use it as a trampoline stack for other kernel entry points besides SYSENTER. So store the task stack pointer in x86_tss.sp1, which is otherwise unused by the hardware, as Linux doesn't make use of Ring 1. Signed-off-by: Joerg Roedel --- arch/x86/kernel/asm-offsets_32.c | 2 +- arch/x86/kernel/process_32.c | 2 ++ 2 files changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/asm-offsets_32.c b/arch/x86/kernel/asm-offsets_32.c index f452bfd..b97e48c 100644 --- a/arch/x86/kernel/asm-offsets_32.c +++ b/arch/x86/kernel/asm-offsets_32.c @@ -47,7 +47,7 @@ void foo(void) BLANK(); /* Offset from the sysenter stack to tss.sp0 */ - DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp0) - + DEFINE(TSS_entry_stack, offsetof(struct cpu_entry_area, tss.x86_tss.sp1) - offsetofend(struct cpu_entry_area, entry_stack_page.stack)); #ifdef CONFIG_CC_STACKPROTECTOR diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index 5224c60..097d36a 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -292,6 +292,8 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p) this_cpu_write(cpu_current_top_of_stack, (unsigned long)task_stack_page(next_p) + THREAD_SIZE); + /* SYSENTER reads the task-stack from tss.sp1 */ + this_cpu_write(cpu_tss_rw.x86_tss.sp1, next_p->thread.sp0); /* * Restore %gs if needed (which is common) -- 2.7.4