From nobody Sun Feb 8 18:49:47 2026 Received: from mail-lf1-f50.google.com (mail-lf1-f50.google.com [209.85.167.50]) (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 3743F207A17 for ; Tue, 29 Oct 2024 10:53:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.50 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199190; cv=none; b=Ki2tW35FDc0OsPCeMwaB4yUNUfUrWRpsBQXvTua1/a5QDbImzahM8j2+1kvBFHmeAI1PZIHmHMVdJG8x4cFhquIoodAYPmiZ1qVikj7KSIsWGBjOI1JDRGXD6bhfG9oqiV8+qrd7wcjoaiCxPSbg9f65i8XKnDAf/i5Veu7mH7g= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730199190; c=relaxed/simple; bh=Xo+V1CZRSvq8YRy8tU8+41AjinOUKFVT3YCYSnKFWvk=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=fkUkRY7k+pRs5BXV8CuByoEee30Zg1oW2AmZ8SOEMfoTlNZYBHmE8AZr0Y+raYip0XeKWIgrnxqatVI4KwgZVCpYff+lS/xeC5ULSGJ/FQkNGnc5/NiucTwqgbWk4yHyPPuxcSJgHxi7MFKHkK1ikQYqnF6ebZfL1EVdzxDA6Nc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org; spf=pass smtp.mailfrom=linaro.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b=mCXQFpnw; arc=none smtp.client-ip=209.85.167.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linaro.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linaro.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=linaro.org header.i=@linaro.org header.b="mCXQFpnw" Received: by mail-lf1-f50.google.com with SMTP id 2adb3069b0e04-53a0c160b94so5892395e87.2 for ; Tue, 29 Oct 2024 03:53:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; t=1730199186; x=1730803986; darn=vger.kernel.org; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:from:to:cc:subject:date:message-id :reply-to; bh=+Ojsf1FDD3J/q7BWA6tzk7mG2LcyH7oHP8nC2ES9d2U=; b=mCXQFpnww5d0GTztfQ48K7FTPQEV4DAcHqDCNguo4J8ZLFTakNvWsMujP6mTMx1hq3 jo0X2W9gItdYYZzFdVX8mPcImjHTBCNre0k7wh2ylRIYvBrRzcbX+vGUY5qwSDzbgPq3 goYIr4iNbIBZFanWqpKKEfsPTfIlsE4TKoDzECT3ZBhAAnlieBygatZ+xiij8zfeBpKp M4xbCMk9zPf3i9xcqVJaV9+4VOalM7ryypsOOoUS/IkXcnqn3PLaK9zGLRu6VHBQgMgj ytTKuGCww9ijKC9sa8YS92thCsbfmXPez7z4p8ijRw05QqbkVKV/K9jfq2vn6mvRZkXp AxCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730199186; x=1730803986; h=cc:to:in-reply-to:references:message-id:content-transfer-encoding :mime-version:subject:date:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=+Ojsf1FDD3J/q7BWA6tzk7mG2LcyH7oHP8nC2ES9d2U=; b=JYKkJxQVbTRzQf50OYXlqWRhwur+2PeXmCXXQGOShFMoJhIVwXMKxKqQk8JqXax73X NCmFyOWcZ2fhvp+CkppufmM/W6lRESJKXM4sk0COlDaFssHeSFl5t4RlFOGv//6nu0DM 4gsRxxMCyB0tY5vz93Y8163AZmMMmyrENAWja9olHkBRPoDiogvHIO+azS+ZE3+VgKtu wKoNiNI1K6HkwEYybHJYXP9G4Rs6N6WlOLjYDSmAvASoYZPCGFmUhlO56f0Rz8MHt9Gn KMBg8ZLBidMFZ2dVh4Uduin0/zho709iQrWD3FzqT1x/iSejOAWDRB9woiSh+81hh8um 3/kg== X-Forwarded-Encrypted: i=1; AJvYcCXQIXa0dF6QPqp6KuOawD7oO8M9Ap2GW7ioIWnCQPPVCuqbJuDGWQOfS+/N9ZCzXOiVchWDEl4Ebr9lXPw=@vger.kernel.org X-Gm-Message-State: AOJu0Yx4OEGHUC7204eHi/M26U5bnv88CZfCzR1g9zcUKGRxNfR6lcWb c6jTTiTBkGS5aMel5YYQyO2DdieGGZJftcOTY4CISIWEHbZblj9JL+Q2fVibz6Y= X-Google-Smtp-Source: AGHT+IFXG4+qFOLuZpZcmM1Lay+S0Jgq0PH3SGHMivCPOmdGtmS+4HV+qVrZtyBne6W8UBHPMqEfcA== X-Received: by 2002:ac2:4e0b:0:b0:536:741a:6bad with SMTP id 2adb3069b0e04-53b348c1086mr5244851e87.12.1730199186296; Tue, 29 Oct 2024 03:53:06 -0700 (PDT) Received: from lino.lan ([85.235.12.238]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-53b2e12452fsm1351307e87.73.2024.10.29.03.53.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Oct 2024 03:53:04 -0700 (PDT) From: Linus Walleij Date: Tue, 29 Oct 2024 11:52:51 +0100 Subject: [PATCH RFC v2 11/28] ARM: entry: Merge the common and trace entry code 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="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20241029-arm-generic-entry-v2-11-573519abef38@linaro.org> References: <20241029-arm-generic-entry-v2-0-573519abef38@linaro.org> In-Reply-To: <20241029-arm-generic-entry-v2-0-573519abef38@linaro.org> To: Oleg Nesterov , Russell King , Kees Cook , Andy Lutomirski , Will Drewry , Frederic Weisbecker , "Paul E. McKenney" , Jinjie Ruan , Arnd Bergmann , Ard Biesheuvel , Al Viro Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Linus Walleij X-Mailer: b4 0.14.0 The trace entry code now can handle recursive and complex calls in C using stack. Move the common code over to using that approach. We now use the ret_fast_syscall return path also when tracing, which appears to work just fine. Signed-off-by: Linus Walleij --- arch/arm/include/asm/syscall.h | 3 +-- arch/arm/kernel/entry-common.S | 61 +++++++++-----------------------------= ---- arch/arm/kernel/syscall.c | 34 +++++++++++------------ 3 files changed, 28 insertions(+), 70 deletions(-) diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index cb0073c4151b..9c664d8c5718 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -19,8 +19,7 @@ =20 extern const unsigned long sys_call_table[]; =20 -int invoke_syscall(void *table, struct pt_regs *regs, int scno, void *retp= ); -void invoke_syscall_trace(void *table, struct pt_regs *regs); +int invoke_syscall_trace(void *table, struct pt_regs *regs, int scno); =20 static inline int syscall_get_nr(struct task_struct *task, struct pt_regs *regs) diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S index dbc947d301ec..f0f1f8723965 100644 --- a/arch/arm/kernel/entry-common.S +++ b/arch/arm/kernel/entry-common.S @@ -39,7 +39,6 @@ saved_pc .req lr * from those features make this path too inefficient. */ ret_fast_syscall: -__ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) disable_irq_notrace @ disable interrupts @@ -47,13 +46,13 @@ __ret_fast_syscall: movs r1, r1, lsl #16 bne fast_work_pending =20 - restore_user_regs fast =3D 1, offset =3D S_OFF + restore_user_regs fast =3D 0, offset =3D S_OFF UNWIND(.fnend ) ENDPROC(ret_fast_syscall) =20 /* Ok, we need to do extra processing, enter the slow path. */ fast_work_pending: - str r0, [sp, #S_R0+S_OFF]! @ returned r0 + add sp, sp, #(S_R0 + S_OFF) /* fall through to work_pending */ #else /* @@ -63,10 +62,9 @@ fast_work_pending: * call. */ ret_fast_syscall: -__ret_fast_syscall: UNWIND(.fnstart ) UNWIND(.cantunwind ) - str r0, [sp, #S_R0 + S_OFF]! @ save returned r0 + add sp, sp, #(S_R0 + S_OFF) #if IS_ENABLED(CONFIG_DEBUG_RSEQ) /* do_rseq_syscall needs interrupts enabled. */ mov r0, sp @ 'regs' @@ -83,7 +81,9 @@ ENDPROC(ret_fast_syscall) #endif =20 tst r1, #_TIF_SYSCALL_WORK - bne __sys_trace_return_nosave + beq slow_work_pending + b ret_to_user + slow_work_pending: mov r0, sp @ 'regs' bl do_work_pending @@ -257,19 +257,15 @@ ENTRY(vector_swi) str scno, [tsk, #TI_ABI_SYSCALL] #endif mov r1, sp @ put regs into r1 - ldr r10, [tsk, #TI_FLAGS] @ check for syscall tracing stmdb sp!, {r4, r5} @ push fifth and sixth args - - tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls? - bne __sys_trace - mov r0, tbl - /* r1 already contains regs */ mov r2, scno @ syscall number from r7 - /* We return here no matter what, also pass this as an argument */ - badr lr, __ret_fast_syscall - mov r3, lr - b invoke_syscall + bl invoke_syscall_trace + cmp r0, #0 + beq ret_fast_syscall + /* This path taken when tracing */ + add sp, sp, #(S_R0 + S_OFF) + b ret_to_user =20 #if defined(CONFIG_OABI_COMPAT) || !defined(CONFIG_AEABI) /* @@ -289,20 +285,6 @@ ENTRY(vector_swi) ENDPROC(vector_swi) .ltorg =20 - /* - * This is the really slow path. We're going to be doing - * context switches, and waiting for our parent to respond. - */ -__sys_trace: - add r1, sp, #S_R0 + S_OFF @ pointer to regs - mov r0, tbl - bl invoke_syscall_trace - add sp, sp, #S_OFF @ restore stack pointer - b ret_to_user - -__sys_trace_return_nosave: - b ret_to_user - .macro syscall_table_start, sym .equ __sys_nr, 0 .type \sym, #object @@ -402,25 +384,6 @@ sys_mmap2: b sys_mmap_pgoff ENDPROC(sys_mmap2) =20 -/* - * This call wants: - * r0: syscall table - * r1: regs - * r2: syscall number - * r3: pointer to return function - */ -SYM_TYPED_FUNC_START(invoke_syscall_asm) -#ifdef CONFIG_CPU_SPECTRE - csdb -#endif - mov tbl, r0 - mov scno, r2 - mov lr, r3 @ return address - ldmia r1, {r0 - r3} @ reload r0-r3 - /* Arguments 5 and 6 are (hopefully) on the stack */ - ldr pc, [tbl, scno, lsl #2] @ call sys_* routine -SYM_FUNC_END(invoke_syscall_asm) - /* * This call wants: * r0: syscall table diff --git a/arch/arm/kernel/syscall.c b/arch/arm/kernel/syscall.c index 3ee367958298..ab9e66da0a80 100644 --- a/arch/arm/kernel/syscall.c +++ b/arch/arm/kernel/syscall.c @@ -3,48 +3,44 @@ #include #include =20 -int invoke_syscall_asm(void *table, struct pt_regs *regs, int scno, void *= retp); - -__visible int invoke_syscall(void *table, struct pt_regs *regs, int scno, = void *retp) +static inline bool has_syscall_work(unsigned long flags) { - if (scno < NR_syscalls) - /* Doing this with return makes sure the stack gets pop:ed */ - return invoke_syscall_asm(table, regs, scno, retp); - - if (scno >=3D __ARM_NR_BASE) - return arm_syscall(scno, regs); - - return sys_ni_syscall(); + return unlikely(flags & _TIF_SYSCALL_WORK); } =20 int invoke_syscall_trace_asm(void *table, struct pt_regs *regs, int scno); =20 -__visible void invoke_syscall_trace(void *table, struct pt_regs *regs) +__visible int invoke_syscall_trace(void *table, struct pt_regs *regs, int = scno) { - int scno; + unsigned long flags =3D read_thread_flags(); int ret; =20 - scno =3D syscall_trace_enter(regs); - if (scno =3D=3D -1) - goto trace_exit_nosave; + if (has_syscall_work(flags)) { + scno =3D syscall_trace_enter(regs); + if (scno =3D=3D -1) + goto trace_exit_nosave; + } =20 if (scno < NR_syscalls) { ret =3D invoke_syscall_trace_asm(table, regs, scno); - goto trace_exit_save; + goto exit_save; } =20 if (scno >=3D __ARM_NR_BASE) { ret =3D arm_syscall(scno, regs); - goto trace_exit_save; + goto exit_save; } =20 ret =3D sys_ni_syscall(); =20 -trace_exit_save: +exit_save: /* Save return value from syscall */ regs->ARM_r0 =3D ret; + if (!has_syscall_work(flags)) + return 0; =20 trace_exit_nosave: local_irq_enable(); syscall_trace_exit(regs); + return 1; } --=20 2.46.2