From: Peter Zijlstra <peterz@infradead.org>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Kai Huang <kai.huang@intel.com>,
tglx@linutronix.de, bp@alien8.de, mingo@redhat.com,
hpa@zytor.com, kirill.shutemov@linux.intel.com,
rick.p.edgecombe@intel.com, x86@kernel.org,
samitolvanen@google.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86/virt/tdx: Add ENDBR for low level SEAMCALL assembly functions
Date: Thu, 5 Jun 2025 16:59:14 +0200 [thread overview]
Message-ID: <20250605145914.GW39944@noisy.programming.kicks-ass.net> (raw)
In-Reply-To: <ae0adccd-25d2-4dd3-b1b9-f7ba0c13367c@intel.com>
On Thu, Jun 05, 2025 at 07:54:48AM -0700, Dave Hansen wrote:
> On 6/5/25 07:21, Peter Zijlstra wrote:
> > -static inline u64 sc_retry(sc_func_t func, u64 fn,
> > - struct tdx_module_args *args)
> > +static __always_inline u64 sc_retry(const sc_func_t func, u64 fn,
> > + struct tdx_module_args *args)
> > {
> > int retry = RDRAND_RETRY_LOOPS;
>
> Practically, I can see how this works. If the compiler doesn't inline
> sc_retry(), it stops being able to guarantee that the function pointer
> value is known.
>
> My only worry is that the compiler decides to be stupid for some other
> reason, it could start generating indirect calls again.
>
> Are we confident that __always_inline will keep the compiler from
> generating indirect calls?
Fairly sure. I've used this elsewhere too.
Also, if it ever decides to be that stupid, I'm going to log a bug and
call it broken.
next prev parent reply other threads:[~2025-06-05 14:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-04 0:38 Kai Huang
2025-06-04 19:46 ` Dave Hansen
2025-06-04 23:16 ` Huang, Kai
2025-06-04 23:23 ` Dave Hansen
2025-06-04 23:27 ` Huang, Kai
2025-06-04 23:57 ` Huang, Kai
2025-06-05 13:12 ` Huang, Kai
2025-06-05 13:10 ` [PATCH v2] x86/virt/tdx: Annotate TDX assembly to allow indirect calls Kai Huang
2025-06-05 14:07 ` [PATCH] x86/virt/tdx: Add ENDBR for low level SEAMCALL assembly functions Peter Zijlstra
2025-06-05 14:21 ` Peter Zijlstra
2025-06-05 14:54 ` Dave Hansen
2025-06-05 14:59 ` Peter Zijlstra [this message]
2025-06-05 23:20 ` Huang, Kai
2025-06-05 23:23 ` Dave Hansen
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