From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A7AC1D27AF for ; Tue, 5 Nov 2024 10:40:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730803229; cv=none; b=Z6VL8uFXVA1Cd7ka5a5y3PNCIx6sAUepu5R11m66XgdXzOp5s13uh3/YIwsnO9+Yenf9JPFg8ZoNdIcEjqbNRMIXV5k+chH84Z7yNmFZkm1nrnDw6QTm/Ol9V+JOLmRHnGPeL3dtWSN5DgsoKsbvhAs80YMOsecTpDAaneto/QI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730803229; c=relaxed/simple; bh=lPVvusvKe75N4H8WC79obt8DA6iLji14EOgIcIUKPZE=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=tAtDN8gpbpFMHRqVOcsMP732RVr0Es/V2DsdWScMfrV+PJV1QhqGa9WjNzhTt5TkR2v5bdaEd/ByQffWsmYbOwu3h+VB783lc9aGIYNueMMrdNfG1MfyUQJpedCjpP7o4HRr4CeYU9f1rCCzJ6ypxKRhCUNMeeVyp9X1NFtBa+o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=bJh4qlmL; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="bJh4qlmL" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=t3NDHAEOvBkB05lX8OeacuHHWaOcStiYW+e4UMOvUlM=; b=bJh4qlmLR1mo5ftmOnCjDCwYLF 2hPKn/FuRwkrr9FJNpd1AHgzLGmlofM4gUfskSFZraFEZtFBHO6DfqVjtGmr2A6C+2oIydqW2Wq2G MOOYasntQzgrygSO8WgY2EPlP+tRAB0cF+g/9RkoCSlcbNLa4h089fnsYtKHw+j1WrpawSnlMIo3h yfSMNZV+WxLwb+PFHELENsOfd3eXyGVe6zhuiWOXNA7pj11oul1Qk2Kuhw6wZqahhdNDn0qQvdLDT 7plslLUrVF84Qa1/3/FKcI59Ht9wxJcuY69mHseak4uZctX2Sa2OXFPNsh/EPg6ztMj0KFbMoFJ1L R6lI8Tlw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98 #2 (Red Hat Linux)) id 1t8Gyy-0000000Bj09-3t63; Tue, 05 Nov 2024 10:40:21 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 15BD0300324; Tue, 5 Nov 2024 11:40:20 +0100 (CET) Date: Tue, 5 Nov 2024 11:40:20 +0100 From: Peter Zijlstra To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, alyssa.milburn@intel.com, scott.d.constable@intel.com, joao@overdrivepizza.com, andrew.cooper3@citrix.com, jpoimboe@kernel.org, jose.marchesi@oracle.com, hjl.tools@gmail.com, ndesaulniers@google.com, samitolvanen@google.com, nathan@kernel.org, ojeda@kernel.org, kees@kernel.org, alexei.starovoitov@gmail.com Subject: Re: [PATCH 09/14] x86/ibt: Implement IBT+ Message-ID: <20241105104020.GC10375@noisy.programming.kicks-ass.net> References: <20240927194856.096003183@infradead.org> <20240927194925.283644921@infradead.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240927194925.283644921@infradead.org> On Fri, Sep 27, 2024 at 09:49:05PM +0200, Peter Zijlstra wrote: > +#ifdef CONFIG_X86_KERNEL_IBT_PLUS > +__init_or_module void apply_direct_call_offset(s32 *start, s32 *end) > +{ > + s32 *s; > + > + /* > + * incompatible with call depth tracking > + */ > + if (cpu_feature_enabled(X86_FEATURE_CALL_DEPTH)) > + return; > + > + for (s = start; s < end; s++) { > + void *dest, *addr = (void *)s + *s; > + struct insn insn; > + int ret; > + > + ret = insn_decode_kernel(&insn, addr); > + if (WARN_ON_ONCE(ret < 0)) > + continue; > + > + dest = addr + insn.length + insn.immediate.value; > + if (!is_endbr(dest)) > + continue; > + > + switch (insn.opcode.bytes[0]) { > + case CALL_INSN_OPCODE: > + case JMP32_INSN_OPCODE: > + apply_reloc(4, addr+1, 4); > + continue; > + > + case JMP8_INSN_OPCODE: > + case 0x70 ... 0x7f: /* Jcc.d8 */ > + apply_reloc(1, addr+1, 4); > + continue; *sigh*... I have a clang-19 build (thanks 0day) that uses a jmp.d8 +0x7e as a tail-call, guess how well it goes adding 4 to that :-( Luckily the next instruction is a giant (alignment) NOP, so I *could* go fix that up, but perhaps this is pushing things too far ... > + > + case 0x0f: > + switch (insn.opcode.bytes[1]) { > + case 0x80 ... 0x8f: > + apply_reloc(4, addr+2, 4); > + continue; > + > + default: > + break; > + } > + break; > + > + default: > + break; > + } > + > + printk("at: %pS, instruction: %*ph\n", addr, insn.length, addr); > + BUG(); > + } > +} > +#else > +__init_or_module void apply_direct_call_offset(s32 *start, s32 *end) { } > +#endif