linux-kernel - [PATCH] LoongArch: Ensure FP/SIMD registers in the core dump file is up to date

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-next>] [day] [month] [year] [list]

Message-Id: <20230825114224.3886577-1-chenhuacai@loongson.cn>
Date:   Fri, 25 Aug 2023 19:42:24 +0800
From:   Huacai Chen <chenhuacai@...ngson.cn>
To:     Arnd Bergmann <arnd@...db.de>, Huacai Chen <chenhuacai@...nel.org>
Cc:     loongarch@...ts.linux.dev, linux-arch@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>,
        Guo Ren <guoren@...nel.org>, Xuerui Wang <kernel@...0n.name>,
        Jiaxun Yang <jiaxun.yang@...goat.com>,
        linux-kernel@...r.kernel.org, loongson-kernel@...ts.loongnix.cn,
        Huacai Chen <chenhuacai@...ngson.cn>
Subject: [PATCH] LoongArch: Ensure FP/SIMD registers in the core dump file is up to date

This is a port of commit 379eb01c21795edb4c ("riscv: Ensure the value
of FP registers in the core dump file is up to date").

The values of FP/SIMD registers in the core dump file come from the
thread.fpu. However, kernel saves the FP/SIMD registers only before
scheduling out the process. If no process switch happens during the
exception handling, kernel will not have a chance to save the latest
values of FP/SIMD registers. So it may cause their values in the core
dump file incorrect. To solve this problem, force fpr_get()/simd_get()
to save the FP/SIMD registers into the thread.fpu if the target task
equals the current task.

Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
---
 arch/loongarch/include/asm/fpu.h | 22 ++++++++++++++++++----
 arch/loongarch/kernel/ptrace.c   |  4 ++++
 2 files changed, 22 insertions(+), 4 deletions(-)

diff --git a/arch/loongarch/include/asm/fpu.h b/arch/loongarch/include/asm/fpu.h
index b541f6248837..08a45e9fd15c 100644
--- a/arch/loongarch/include/asm/fpu.h
+++ b/arch/loongarch/include/asm/fpu.h
@@ -173,16 +173,30 @@ static inline void restore_fp(struct task_struct *tsk)
 		_restore_fp(&tsk->thread.fpu);
 }
 
-static inline union fpureg *get_fpu_regs(struct task_struct *tsk)
+static inline void get_fpu_regs(struct task_struct *tsk)
 {
+	unsigned int euen;
+
 	if (tsk == current) {
 		preempt_disable();
-		if (is_fpu_owner())
+
+		euen = csr_read32(LOONGARCH_CSR_EUEN);
+
+#ifdef CONFIG_CPU_HAS_LASX
+		if (euen & CSR_EUEN_LASXEN)
+			_save_lasx(&current->thread.fpu);
+		else
+#endif
+#ifdef CONFIG_CPU_HAS_LSX
+		if (euen & CSR_EUEN_LSXEN)
+			_save_lsx(&current->thread.fpu);
+		else
+#endif
+		if (euen & CSR_EUEN_FPEN)
 			_save_fp(&current->thread.fpu);
+
 		preempt_enable();
 	}
-
-	return tsk->thread.fpu.fpr;
 }
 
 static inline int is_simd_owner(void)
diff --git a/arch/loongarch/kernel/ptrace.c b/arch/loongarch/kernel/ptrace.c
index 2bb5ec55ae1e..209e3d29e0b2 100644
--- a/arch/loongarch/kernel/ptrace.c
+++ b/arch/loongarch/kernel/ptrace.c
@@ -148,6 +148,8 @@ static int fpr_get(struct task_struct *target,
 {
 	int r;
 
+	get_fpu_regs(target);
+
 	if (sizeof(target->thread.fpu.fpr[0]) == sizeof(elf_fpreg_t))
 		r = gfpr_get(target, &to);
 	else
@@ -279,6 +281,8 @@ static int simd_get(struct task_struct *target,
 {
 	const unsigned int wr_size = NUM_FPU_REGS * regset->size;
 
+	get_fpu_regs(target);
+
 	if (!tsk_used_math(target)) {
 		/* The task hasn't used FP or LSX, fill with 0xff */
 		copy_pad_fprs(target, regset, &to, 0);
-- 
2.39.3