From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists1p.gnu.org (lists1p.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 09E0BCD8C88 for ; Sun, 7 Jun 2026 14:05:28 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists1p.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1wWE6y-0004MX-1y; Sun, 07 Jun 2026 10:04:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists1p.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wWE6w-0004MP-Ir for qemu-devel@nongnu.org; Sun, 07 Jun 2026 10:04:22 -0400 Received: from tor.source.kernel.org ([2600:3c04:e001:324:0:1991:8:25]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1wWE6u-00087J-TF for qemu-devel@nongnu.org; Sun, 07 Jun 2026 10:04:22 -0400 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id 45E5160018; Sun, 7 Jun 2026 14:04:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5DF3C1F00893; Sun, 7 Jun 2026 14:04:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780841060; bh=7LLRWlYl4f50tTS2x2GJ/eFkVK++jmXZ/i6kKIARBlk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=i+htPQebVybQqK5/xMve51dnxXppeqheHJ0LhRbOJIfvP2/g1DeQGSmJ3Spz4KLso J7ZR48V+9re+nA2seLz1df7Q/rg1u6oNHJjRyb60q3WnACDsp9tHgZmeqMOUOi1d8g ew8YNYmEYUvbo0hZ+xAALPctEKX+ELrNwgKWpCK3DosCsr0fPdToq4dnHIflLcs9TJ X19BnA9SeQ2XxBEMAg4HEn4ofdW2CTSjJkE+OeZ1O6xOtVq+bWuKJFZex6yFy7adVl oV6SCOvNAlrOyFpaS85YnkldRsFV/I/vqATTYtuZYTBivACmTFMqAm0LgoCe1udd2O mOvnuV+7MOL/g== From: Helge Deller To: qemu-devel@nongnu.org Cc: Pierrick Bouvier , Laurent Vivier , Yoshinori Sato , Max Filippov , Helge Deller , Matt Turner Subject: [PATCH 09/10] linux-user/xtensa: restore FP rounding mode on sigreturn Date: Sun, 7 Jun 2026 16:03:55 +0200 Message-ID: <20260607140356.10702-10-deller@kernel.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260607140356.10702-1-deller@kernel.org> References: <20260607140356.10702-1-deller@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=2600:3c04:e001:324:0:1991:8:25; envelope-from=deller@kernel.org; helo=tor.source.kernel.org X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.445, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org From: Matt Turner The Xtensa FCR rounding-mode (RM) bits are not held only in env->uregs[FCR]: they are also reflected into env->fp_status via set_float_rounding_mode(). Similarly, FSR exception flags are mirrored into env->fp_status. Every write to FCR/FSR goes through helper_wur_fpu{2k,}_fcr / helper_wur_fpu_fsr which keep the two in sync. restore_sigcontext() previously wrote nothing back for xtregs, leaving env->fp_status with whatever rounding mode and exception flags the signal handler last installed. Any FP instruction in the interrupted code could then operate with the wrong mode. Add a minimal target_xtensa_xtregs sub-frame carrying FCR and FSR. setup_sigcontext() saves the current values and points sc_xtregs at the sub-frame when XTENSA_OPTION_FP_COPROCESSOR or XTENSA_OPTION_DFP_COPROCESSOR is present (both use env->fp_status driven by FCR/FSR). restore_sigcontext() reads sc_xtregs; if non-zero it restores FCR and FSR through cpu_set_fcr()/cpu_set_fsr() so fp_status round-trips correctly across signal delivery. Signed-off-by: Matt Turner Cc: Max Filippov Signed-off-by: Helge Deller --- linux-user/xtensa/signal.c | 36 +++++++++++++++++++++++++++++++----- 1 file changed, 31 insertions(+), 5 deletions(-) diff --git a/linux-user/xtensa/signal.c b/linux-user/xtensa/signal.c index ef8b0c3a27..fef23952b7 100644 --- a/linux-user/xtensa/signal.c +++ b/linux-user/xtensa/signal.c @@ -21,6 +21,7 @@ #include "user-internals.h" #include "signal-common.h" #include "linux-user/trace.h" +#include "target/xtensa/cpu.h" struct target_sigcontext { abi_ulong sc_pc; @@ -43,10 +44,15 @@ struct target_ucontext { target_sigset_t tuc_sigmask; }; +struct target_xtensa_xtregs { + uint32_t fcr; + uint32_t fsr; +}; + struct target_rt_sigframe { target_siginfo_t info; struct target_ucontext uc; - /* TODO: xtregs */ + struct target_xtensa_xtregs xtregs; uint8_t retcode[6]; abi_ulong window[4]; }; @@ -107,6 +113,7 @@ static int flush_window_regs(CPUXtensaState *env) } static int setup_sigcontext(struct target_rt_sigframe *frame, + abi_ulong frame_addr, CPUXtensaState *env) { struct target_sigcontext *sc = &frame->uc.tuc_mcontext; @@ -123,8 +130,15 @@ static int setup_sigcontext(struct target_rt_sigframe *frame, for (i = 0; i < 16; ++i) { __put_user(env->regs[i], sc->sc_a + i); } - __put_user(0, &sc->sc_xtregs); - /* TODO: xtregs */ + if (xtensa_option_enabled(env->config, XTENSA_OPTION_FP_COPROCESSOR) || + xtensa_option_enabled(env->config, XTENSA_OPTION_DFP_COPROCESSOR)) { + __put_user(env->uregs[FCR], &frame->xtregs.fcr); + __put_user(cpu_get_fsr(env), &frame->xtregs.fsr); + __put_user(frame_addr + offsetof(struct target_rt_sigframe, xtregs), + &sc->sc_xtregs); + } else { + __put_user(0, &sc->sc_xtregs); + } return 1; } @@ -190,7 +204,7 @@ void setup_rt_frame(int sig, struct target_sigaction *ka, __put_user(0, &frame->uc.tuc_flags); __put_user(0, &frame->uc.tuc_link); target_save_altstack(&frame->uc.tuc_stack, env); - if (!setup_sigcontext(frame, env)) { + if (!setup_sigcontext(frame, frame_addr, env)) { unlock_user_struct(frame, frame_addr, 0); goto give_sigsegv; } @@ -266,7 +280,19 @@ static void restore_sigcontext(CPUXtensaState *env, for (i = 0; i < 16; ++i) { __get_user(env->regs[i], sc->sc_a + i); } - /* TODO: xtregs */ + { + abi_ulong xtregs_addr; + + __get_user(xtregs_addr, &sc->sc_xtregs); + if (xtregs_addr) { + uint32_t fcr, fsr; + + __get_user(fcr, &frame->xtregs.fcr); + __get_user(fsr, &frame->xtregs.fsr); + cpu_set_fcr(env, fcr); + cpu_set_fsr(env, fsr); + } + } } long do_rt_sigreturn(CPUXtensaState *env) -- 2.54.0