From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f201.google.com (mail-yw1-f201.google.com [209.85.128.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9E03A7E for ; Tue, 31 May 2022 17:59:16 +0000 (UTC) Received: by mail-yw1-f201.google.com with SMTP id 00721157ae682-30974094b5cso87658307b3.20 for ; Tue, 31 May 2022 10:59:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:message-id:mime-version:subject:from:to:cc; bh=43It4tY6rrOkbTtcYBE6N6l07cvQ+0q2w708BzUCfdQ=; b=cXZh0iB2YUeKYWSq/DnFCdl8EfWrduss4aKiLDcCamYQxpSehyBOr4Mc2Id9+hCYIK pk3kI/d2LS9MbBzExeYMvn/w+d4BmVB0YXSZ+skDu8gCDQ3DefzaGupJW4tsBoH/0Tg+ itlbwwf2hGrxNFki2bplHtgCS3/hLVA8ID0F6auJlQRpeiZQCF8S7rUif4r9upjflXJL tta6rNIuKi3PgSzLcLV7gdpXYPxvnG4I6+k00Zk93DDHs0fuyQHXktG7wVbOX3zpHbqC rMlQDftQ/vo1M9BEP+YAucYerbdaEQaRjqsL2EpO/thbKjx2KFc7UlCDU1haZRZ2U9Vu luaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=43It4tY6rrOkbTtcYBE6N6l07cvQ+0q2w708BzUCfdQ=; b=fT9M8VS73udVqEBiaYN1aek7exlYN8/Wi5yY2QVbYycAAiQW/XCbTwY2597/ev0PYE dGcwpoUh7M9ntbd745L/eifIsCcvNexD9FpJso4SqCezw3Pw+cs73+t90x28STVltME0 mroOqBg1yyygKk+7VqkAEv3BRX6Q5IqtMugt+v31NDNpnI2V/l6Ou8dWqB2dp+sd+Fe4 KZ0mK2H4Eti1zcmM6spU7zWEr4puRfDqM+YMwmCvTaF2ZoeJz3WWdujBkCZrGt3FROKm +ordZuM8roJWg2ca9xc6dBIr6q3SCK0cnNH4dqL4TwahC4a6ABbT6lONn0n0Mo8AclJS dOpQ== X-Gm-Message-State: AOAM533yVMV/fMKRBNHSuxxj0WYia3K72gMcmOY4CZaP2PIWGVUN8ENT CA2+f4hobmF8qMpxYEP1U0gwXG9YVhFs+MlP5BY= X-Google-Smtp-Source: ABdhPJzYg2PfrP7VAcOIhffi51zcFsynl9sjjnou+I9ggql8TYO0BMoIPH151gDfL/0kxSkXR0y1Lgi6goCkxQD9zNE= X-Received: from samitolvanen1.mtv.corp.google.com ([2620:15c:201:2:1067:12fc:51e8:95dc]) (user=samitolvanen job=sendgmr) by 2002:a05:6902:13c2:b0:641:b6d:a151 with SMTP id y2-20020a05690213c200b006410b6da151mr59039298ybu.348.1654019955516; Tue, 31 May 2022 10:59:15 -0700 (PDT) Date: Tue, 31 May 2022 10:59:10 -0700 Message-Id: <20220531175910.890307-1-samitolvanen@google.com> Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Developer-Key: i=samitolvanen@google.com; a=openpgp; fpr=35CCFB63B283D6D3AEB783944CB5F6848BBC56EE X-Developer-Signature: v=1; a=openpgp-sha256; l=1904; h=from:subject; bh=3APPK7JF94JGhsLYsP/k0BDbTWmcKvSdC5cUDwc7HEc=; b=owEB7QES/pANAwAKAUy19oSLvFbuAcsmYgBilldu8L6b8RrGC/uxYEv0Gt9ac9FJ70jAIdFrFvYx EHOOhWyJAbMEAAEKAB0WIQQ1zPtjsoPW0663g5RMtfaEi7xW7gUCYpZXbgAKCRBMtfaEi7xW7kl4C/ sGCz2eKwsUVqQBfjgycK9T1O2Q00Tu+HFofNAQbx4mkHJHNeWBFRwG6hwpCmtJsW1AQhMexHawitij pRuOxuW5Ao3CKRsq7h1iSypEEHTZS/6XWLZ4UxwcSb92I77OqdviGLpbXPcLemLi/A9xHEY8qGF59K 1I/dRgW2S2WNN/JKkJAmD2dGFd5o5rQ7VNSzkyE1DKve/bllIIPEenvR5Wep0d8UsmTmIlGzgIeceM e/ChPrDIOk5qG+Wu+IU8w7j3qutB0PEBfQ4q87dg2S1ig0AuZM+26vIplp3oRylAQXIVPDgFkRntua HCXqLh35oofnfgIshwTLivkIn6qKnQLkl0QTxTR0yaCSodf/LxrbqP2rMFFHKW4/Ez8KfYrbyTYKIi oYTzkdFvZILF1O7dNfDPlCfOWVDM8lu6KcdQjRJxGi88gu/WOymYVreOEvQCadOf161KxVBiPmrsba XlOq1MdW5ZjjeDMHq020MIhgpTiSklSjuh41GqNOyeM/w= X-Mailer: git-send-email 2.36.1.255.ge46751e96f-goog Subject: [PATCH] cfi: Fix __cfi_slowpath_diag RCU usage with cpuidle From: Sami Tolvanen To: Kees Cook Cc: "Paul E. McKenney" , Nathan Chancellor , Nick Desaulniers , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Sami Tolvanen Content-Type: text/plain; charset="UTF-8" RCU_NONIDLE usage during __cfi_slowpath_diag can result in an invalid RCU state in the cpuidle code path: WARNING: CPU: 1 PID: 0 at kernel/rcu/tree.c:613 rcu_eqs_enter+0xe4/0x138 ... Call trace: rcu_eqs_enter+0xe4/0x138 rcu_idle_enter+0xa8/0x100 cpuidle_enter_state+0x154/0x3a8 cpuidle_enter+0x3c/0x58 do_idle.llvm.6590768638138871020+0x1f4/0x2ec cpu_startup_entry+0x28/0x2c secondary_start_kernel+0x1b8/0x220 __secondary_switched+0x94/0x98 Instead, call rcu_irq_enter/exit to wake up RCU only when needed and disable interrupts for the entire CFI shadow/module check when we do. Signed-off-by: Sami Tolvanen --- kernel/cfi.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/kernel/cfi.c b/kernel/cfi.c index 9594cfd1cf2c..08102d19ec15 100644 --- a/kernel/cfi.c +++ b/kernel/cfi.c @@ -281,6 +281,8 @@ static inline cfi_check_fn find_module_check_fn(unsigned long ptr) static inline cfi_check_fn find_check_fn(unsigned long ptr) { cfi_check_fn fn = NULL; + unsigned long flags; + bool rcu_idle; if (is_kernel_text(ptr)) return __cfi_check; @@ -290,13 +292,21 @@ static inline cfi_check_fn find_check_fn(unsigned long ptr) * the shadow and __module_address use RCU, so we need to wake it * up if necessary. */ - RCU_NONIDLE({ - if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) - fn = find_shadow_check_fn(ptr); + rcu_idle = !rcu_is_watching(); + if (rcu_idle) { + local_irq_save(flags); + rcu_irq_enter(); + } + + if (IS_ENABLED(CONFIG_CFI_CLANG_SHADOW)) + fn = find_shadow_check_fn(ptr); + if (!fn) + fn = find_module_check_fn(ptr); - if (!fn) - fn = find_module_check_fn(ptr); - }); + if (rcu_idle) { + rcu_irq_exit(); + local_irq_restore(flags); + } return fn; } -- 2.36.1.255.ge46751e96f-goog