linux-kernel - [PATCH v3 2/7] riscv: smp: fail booting up smp if inconsistent vlen is detected

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20240318-zve-detection-v3-2-e12d42107fa8@sifive.com>
Date: Mon, 18 Mar 2024 18:39:55 +0800
From: Andy Chiu <andy.chiu@...ive.com>
To: Paul Walmsley <paul.walmsley@...ive.com>, 
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, 
 Andy Chiu <andy.chiu@...ive.com>, Vincent Chen <vincent.chen@...ive.com>, 
 Heiko Stuebner <heiko@...ech.de>, Conor Dooley <conor.dooley@...rochip.com>, 
 Conor Dooley <conor@...nel.org>, Rob Herring <robh+dt@...nel.org>, 
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>, 
 Jonathan Corbet <corbet@....net>
Cc: linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Palmer Dabbelt <palmer@...osinc.com>, 
 Greentime Hu <greentime.hu@...ive.com>, Guo Ren <guoren@...nel.org>, 
 devicetree@...r.kernel.org, linux-doc@...r.kernel.org
Subject: [PATCH v3 2/7] riscv: smp: fail booting up smp if inconsistent
 vlen is detected

Currently we only support Vector for SMP platforms, that is, all SMP
cores have the same vlenb. If we happen to detect a mismatching vlen, it
is better to just fail bootting it up to prevent further race/scheduling
issues.

Also, move .Lsecondary_park forward and chage `tail smp_callin` into a
regular call in the early assembly. So a core would be parked right
after a return from smp_callin. Note that a successful smp_callin
does not return.

Fixes: 7017858eb2d7 ("riscv: Introduce riscv_v_vsize to record size of Vector context")
Reported-by: Conor Dooley <conor.dooley@...rochip.com>
Closes: https://lore.kernel.org/linux-riscv/20240228-vicinity-cornstalk-4b8eb5fe5730@spud/
Signed-off-by: Andy Chiu <andy.chiu@...ive.com>
---
Changelog v2:
 - update commit message to explain asm code change (Conor)
---
 arch/riscv/kernel/head.S    | 14 +++++++-------
 arch/riscv/kernel/smpboot.c | 14 +++++++++-----
 2 files changed, 16 insertions(+), 12 deletions(-)

diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
index 4236a69c35cb..a158fa9f2656 100644
--- a/arch/riscv/kernel/head.S
+++ b/arch/riscv/kernel/head.S
@@ -165,9 +165,15 @@ secondary_start_sbi:
 #endif
 	call .Lsetup_trap_vector
 	scs_load_current
-	tail smp_callin
+	call smp_callin
 #endif /* CONFIG_SMP */
 
+.align 2
+.Lsecondary_park:
+	/* We lack SMP support or have too many harts, so park this hart */
+	wfi
+	j .Lsecondary_park
+
 .align 2
 .Lsetup_trap_vector:
 	/* Set trap vector to exception handler */
@@ -181,12 +187,6 @@ secondary_start_sbi:
 	csrw CSR_SCRATCH, zero
 	ret
 
-.align 2
-.Lsecondary_park:
-	/* We lack SMP support or have too many harts, so park this hart */
-	wfi
-	j .Lsecondary_park
-
 SYM_CODE_END(_start)
 
 SYM_CODE_START(_start_kernel)
diff --git a/arch/riscv/kernel/smpboot.c b/arch/riscv/kernel/smpboot.c
index cfbe4b840d42..1f86ee10192f 100644
--- a/arch/riscv/kernel/smpboot.c
+++ b/arch/riscv/kernel/smpboot.c
@@ -218,6 +218,15 @@ asmlinkage __visible void smp_callin(void)
 	struct mm_struct *mm = &init_mm;
 	unsigned int curr_cpuid = smp_processor_id();
 
+	if (has_vector()) {
+		/*
+		 * Return as early as possible so the hart with a mismatching
+		 * vlen won't boot.
+		 */
+		if (riscv_v_setup_vsize())
+			return;
+	}
+
 	/* All kernel threads share the same mm context.  */
 	mmgrab(mm);
 	current->active_mm = mm;
@@ -230,11 +239,6 @@ asmlinkage __visible void smp_callin(void)
 	numa_add_cpu(curr_cpuid);
 	set_cpu_online(curr_cpuid, 1);
 
-	if (has_vector()) {
-		if (riscv_v_setup_vsize())
-			elf_hwcap &= ~COMPAT_HWCAP_ISA_V;
-	}
-
 	riscv_user_isa_enable();
 
 	/*

-- 
2.44.0.rc2