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Message-Id: <20230731063317.3720-23-xin3.li@intel.com>
Date: Sun, 30 Jul 2023 23:33:03 -0700
From: Xin Li <xin3.li@...el.com>
To: linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-edac@...r.kernel.org, linux-hyperv@...r.kernel.org,
kvm@...r.kernel.org, xen-devel@...ts.xenproject.org
Cc: Jonathan Corbet <corbet@....net>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
"H . Peter Anvin" <hpa@...or.com>,
Andy Lutomirski <luto@...nel.org>,
Oleg Nesterov <oleg@...hat.com>,
Tony Luck <tony.luck@...el.com>,
"K . Y . Srinivasan" <kys@...rosoft.com>,
Haiyang Zhang <haiyangz@...rosoft.com>,
Wei Liu <wei.liu@...nel.org>, Dexuan Cui <decui@...rosoft.com>,
Paolo Bonzini <pbonzini@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
Peter Zijlstra <peterz@...radead.org>,
Juergen Gross <jgross@...e.com>,
Stefano Stabellini <sstabellini@...nel.org>,
Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>,
Josh Poimboeuf <jpoimboe@...nel.org>,
"Paul E . McKenney" <paulmck@...nel.org>,
Catalin Marinas <catalin.marinas@....com>,
Randy Dunlap <rdunlap@...radead.org>,
Steven Rostedt <rostedt@...dmis.org>,
Kim Phillips <kim.phillips@....com>,
Xin Li <xin3.li@...el.com>,
Hyeonggon Yoo <42.hyeyoo@...il.com>,
"Liam R . Howlett" <Liam.Howlett@...cle.com>,
Sebastian Reichel <sebastian.reichel@...labora.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
Jiaxi Chen <jiaxi.chen@...ux.intel.com>,
Babu Moger <babu.moger@....com>,
Jim Mattson <jmattson@...gle.com>,
Sandipan Das <sandipan.das@....com>,
Lai Jiangshan <jiangshanlai@...il.com>,
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Andrew Morton <akpm@...ux-foundation.org>,
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"Eric W . Biederman" <ebiederm@...ssion.com>,
Kees Cook <keescook@...omium.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Masahiro Yamada <masahiroy@...nel.org>,
Ze Gao <zegao2021@...il.com>, Fei Li <fei1.li@...el.com>,
Conghui <conghui.chen@...el.com>,
Ashok Raj <ashok.raj@...el.com>,
"Jason A . Donenfeld" <Jason@...c4.com>,
Mark Rutland <mark.rutland@....com>,
Jacob Pan <jacob.jun.pan@...ux.intel.com>,
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Arnaldo Carvalho de Melo <acme@...hat.com>,
Yantengsi <siyanteng@...ngson.cn>,
Christophe Leroy <christophe.leroy@...roup.eu>,
Sathvika Vasireddy <sv@...ux.ibm.com>
Subject: [PATCH v9 22/36] x86/fred: Add a double fault entry stub for FRED
The IDT event delivery of a double fault pushes an error code into the
orig_ax member of the pt_regs structure, and the error code is passed
as the second argument of its C-handler exc_double_fault(), although
the pt_regs structure is already passed as the first argument.
The existing IDT double fault asm entry code does the following
movq ORIG_RAX(%rsp), %rsi /* get error code into 2nd argument*/
movq $-1, ORIG_RAX(%rsp) /* no syscall to restart */
to set the orig_ax member to -1 just before calling the C-handler.
X86_TRAP_TS, X86_TRAP_NP, X86_TRAP_SS, X86_TRAP_GP, X86_TRAP_AC and
X86_TRAP_CP are all handled in the same way because the IDT event
delivery pushes an error code into their stack frame for them.
The commit d99015b1abbad ("x86: move entry_64.S register saving out of
the macros") introduced the changes to set orig_ax to -1, but I can't
see why. Our tests with FRED seem fine if orig_ax is left unchanged
instead of set to -1. It's probably cleaner and simpler to remove the
second argument from exc_double_fault() while leave orig_ax unchanged
to pass the error code inside the first argument, at least on native
x86_64. That would be a separate, pre-FRED, patch.
For now just add a double fault entry stub for FRED, which simply
calls the existing exc_double_fault().
Tested-by: Shan Kang <shan.kang@...el.com>
Signed-off-by: Xin Li <xin3.li@...el.com>
---
arch/x86/include/asm/fred.h | 1 +
arch/x86/kernel/traps.c | 7 +++++++
2 files changed, 8 insertions(+)
diff --git a/arch/x86/include/asm/fred.h b/arch/x86/include/asm/fred.h
index f559dd9dc4f2..bd701ac87528 100644
--- a/arch/x86/include/asm/fred.h
+++ b/arch/x86/include/asm/fred.h
@@ -116,6 +116,7 @@ DECLARE_FRED_HANDLER(fred_exc_nmi);
DECLARE_FRED_HANDLER(fred_exc_debug);
DECLARE_FRED_HANDLER(fred_exc_page_fault);
DECLARE_FRED_HANDLER(fred_exc_machine_check);
+DECLARE_FRED_HANDLER(fred_exc_double_fault);
#endif /* __ASSEMBLY__ */
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index b10464966a81..49dd92458eb0 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -555,6 +555,13 @@ DEFINE_IDTENTRY_DF(exc_double_fault)
instrumentation_end();
}
+#ifdef CONFIG_X86_FRED
+DEFINE_FRED_HANDLER(fred_exc_double_fault)
+{
+ exc_double_fault(regs, regs->orig_ax);
+}
+#endif
+
DEFINE_IDTENTRY(exc_bounds)
{
if (notify_die(DIE_TRAP, "bounds", regs, 0,
--
2.34.1
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