linux-next.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Next Mailing List <linux-next@vger.kernel.org>,
	jiangshan.ljs@antgroup.com, bp@suse.de
Subject: [PATCH] x86/entry: Fixup objtool/ibt validation
Date: Fri, 20 May 2022 10:26:04 +0200	[thread overview]
Message-ID: <20220520082604.GQ2578@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20220520174954.1c306fc0@canb.auug.org.au>

On Fri, May 20, 2022 at 05:49:54PM +1000, Stephen Rothwell wrote:
> Hi all,
> 
> After merging the tip tree, today's linux-next build (x86_64 allmodconfig)
> produced these warnings:
> 
> vmlinux.o: warning: objtool: vc_switch_off_ist+0x76: relocation to !ENDBR: entry_SYSCALL_64+0x15c
> vmlinux.o: warning: objtool: vc_switch_off_ist+0x8e: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
> vmlinux.o: warning: objtool: vc_switch_off_ist+0x96: relocation to !ENDBR: .entry.text+0x21ca
> vmlinux.o: warning: objtool: vc_switch_off_ist+0xee: relocation to !ENDBR: .entry.text+0x162
> vmlinux.o: warning: objtool: __sev_es_ist_enter+0x5f: relocation to !ENDBR: entry_SYSCALL_64+0x15c
> vmlinux.o: warning: objtool: __sev_es_ist_enter+0x6b: relocation to !ENDBR: .entry.text+0x162
> vmlinux.o: warning: objtool: __sev_es_ist_enter+0x89: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
> vmlinux.o: warning: objtool: __sev_es_ist_enter+0xc0: relocation to !ENDBR: .entry.text+0x21ca
> 
> I don't know what caused this.

It's commit 47f33de4aafb ("x86/sev: Mark the code returning to user space as syscall gap")
that added a bunch of text references.

Lai, Boris, can we please be careful with that?

---
Subject: x86/entry: Fixup objtool/ibt validation

Commit 47f33de4aafb ("x86/sev: Mark the code returning to user space as
syscall gap") added a bunch of text references without annotating them,
resulting in a spree of objtool complaints:

  vmlinux.o: warning: objtool: vc_switch_off_ist+0x77: relocation to !ENDBR: entry_SYSCALL_64+0x15c
  vmlinux.o: warning: objtool: vc_switch_off_ist+0x8f: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
  vmlinux.o: warning: objtool: vc_switch_off_ist+0x97: relocation to !ENDBR: .entry.text+0x21ea
  vmlinux.o: warning: objtool: vc_switch_off_ist+0xef: relocation to !ENDBR: .entry.text+0x162
  vmlinux.o: warning: objtool: __sev_es_ist_enter+0x60: relocation to !ENDBR: entry_SYSCALL_64+0x15c
  vmlinux.o: warning: objtool: __sev_es_ist_enter+0x6c: relocation to !ENDBR: .entry.text+0x162
  vmlinux.o: warning: objtool: __sev_es_ist_enter+0x8a: relocation to !ENDBR: entry_SYSCALL_compat+0xa5
  vmlinux.o: warning: objtool: __sev_es_ist_enter+0xc1: relocation to !ENDBR: .entry.text+0x21ea

Since these text references are used to compare against IP, and are not
an indirect call target, they don't need ENDBR so annotate them away.

Fixes: 47f33de4aafb ("x86/sev: Mark the code returning to user space as syscall gap")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 arch/x86/entry/entry_64.S        | 3 +++
 arch/x86/entry/entry_64_compat.S | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 5ec42bf86a61..221f82b4abc2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -215,9 +215,12 @@ syscall_return_via_sysret:
 	popq	%rdi
 	popq	%rsp
 SYM_INNER_LABEL(entry_SYSRETQ_unsafe_stack, SYM_L_GLOBAL)
+	ANNOTATE_NOENDBR
 	swapgs
 	sysretq
 SYM_INNER_LABEL(entry_SYSRETQ_end, SYM_L_GLOBAL)
+	ANNOTATE_NOENDBR
+	int3
 SYM_CODE_END(entry_SYSCALL_64)

 /*
diff --git a/arch/x86/entry/entry_64_compat.S b/arch/x86/entry/entry_64_compat.S
index 84ffcf504554..95d23364a131 100644
--- a/arch/x86/entry/entry_64_compat.S
+++ b/arch/x86/entry/entry_64_compat.S
@@ -245,6 +245,7 @@ sysret32_from_system_call:
          */
 	movq	RSP-ORIG_RAX(%rsp), %rsp
 SYM_INNER_LABEL(entry_SYSRETL_compat_unsafe_stack, SYM_L_GLOBAL)
+	ANNOTATE_NOENDBR

 	/*
 	 * The original userspace %rsp (RSP-ORIG_RAX(%rsp)) is stored
@@ -263,6 +264,8 @@ SYM_INNER_LABEL(entry_SYSRETL_compat_unsafe_stack, SYM_L_GLOBAL)
 	swapgs
 	sysretl
 SYM_INNER_LABEL(entry_SYSRETL_compat_end, SYM_L_GLOBAL)
+	ANNOTATE_NOENDBR
+	int3
 SYM_CODE_END(entry_SYSCALL_compat)

 /*


      reply	other threads:[~2022-05-20  8:26 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-05-20  7:49 linux-next: build warnings after merge of the tip tree Stephen Rothwell
2022-05-20  8:26 ` Peter Zijlstra [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220520082604.GQ2578@worktop.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=bp@suse.de \
    --cc=hpa@zytor.com \
    --cc=jiangshan.ljs@antgroup.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-next@vger.kernel.org \
    --cc=mingo@redhat.com \
    --cc=sfr@canb.auug.org.au \
    --cc=tglx@linutronix.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).