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([2a01:e0a:999:a3a0:9474:8d75:5115:42cb]) by smtp.gmail.com with ESMTPSA id i2-20020a05600c290200b00402f7b50517sm1768764wmd.40.2023.10.04.08.14.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Oct 2023 08:14:31 -0700 (PDT) From: =?UTF-8?q?Cl=C3=A9ment=20L=C3=A9ger?= To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: =?UTF-8?q?Cl=C3=A9ment=20L=C3=A9ger?= , Atish Patra , Andrew Jones , Evan Green , =?UTF-8?q?Bj=C3=B6rn=20Topel?= , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Ron Minnich , Daniel Maslowski , Conor Dooley Subject: [PATCH v2 8/8] riscv: add support for PR_SET_UNALIGN and PR_GET_UNALIGN Date: Wed, 4 Oct 2023 17:14:05 +0200 Message-ID: <20231004151405.521596-9-cleger@rivosinc.com> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231004151405.521596-1-cleger@rivosinc.com> References: <20231004151405.521596-1-cleger@rivosinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Now that trap support is ready to handle misalignment errors in S-mode, allow the user to control the behavior of misaligned accesses using prctl(PR_SET_UNALIGN). Add an align_ctl flag in thread_struct which will be used to determine if we should SIGBUS the process or not on such fault. Signed-off-by: Cl=C3=A9ment L=C3=A9ger Reviewed-by: Bj=C3=B6rn T=C3=B6pel --- arch/riscv/include/asm/processor.h | 9 +++++++++ arch/riscv/kernel/process.c | 18 ++++++++++++++++++ arch/riscv/kernel/traps_misaligned.c | 6 ++++++ 3 files changed, 33 insertions(+) diff --git a/arch/riscv/include/asm/processor.h b/arch/riscv/include/asm/pr= ocessor.h index 3e23e1786d05..adbe520d07c5 100644 --- a/arch/riscv/include/asm/processor.h +++ b/arch/riscv/include/asm/processor.h @@ -8,6 +8,7 @@ =20 #include #include +#include =20 #include =20 @@ -82,6 +83,7 @@ struct thread_struct { unsigned long bad_cause; unsigned long vstate_ctrl; struct __riscv_v_ext_state vstate; + unsigned long align_ctl; }; =20 /* Whitelist the fstate from the task_struct for hardened usercopy */ @@ -94,6 +96,7 @@ static inline void arch_thread_struct_whitelist(unsigned = long *offset, =20 #define INIT_THREAD { \ .sp =3D sizeof(init_stack) + (long)&init_stack, \ + .align_ctl =3D PR_UNALIGN_NOPRINT, \ } =20 #define task_pt_regs(tsk) \ @@ -134,6 +137,12 @@ extern long riscv_v_vstate_ctrl_set_current(unsigned l= ong arg); extern long riscv_v_vstate_ctrl_get_current(void); #endif /* CONFIG_RISCV_ISA_V */ =20 +extern int get_unalign_ctl(struct task_struct *tsk, unsigned long addr); +extern int set_unalign_ctl(struct task_struct *tsk, unsigned int val); + +#define GET_UNALIGN_CTL(tsk, addr) get_unalign_ctl((tsk), (addr)) +#define SET_UNALIGN_CTL(tsk, val) set_unalign_ctl((tsk), (val)) + #endif /* __ASSEMBLY__ */ =20 #endif /* _ASM_RISCV_PROCESSOR_H */ diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index e32d737e039f..4f21d970a129 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -25,6 +25,7 @@ #include #include #include +#include =20 register unsigned long gp_in_global __asm__("gp"); =20 @@ -41,6 +42,23 @@ void arch_cpu_idle(void) cpu_do_idle(); } =20 +int set_unalign_ctl(struct task_struct *tsk, unsigned int val) +{ + if (!unaligned_ctl_available()) + return -EINVAL; + + tsk->thread.align_ctl =3D val; + return 0; +} + +int get_unalign_ctl(struct task_struct *tsk, unsigned long adr) +{ + if (!unaligned_ctl_available()) + return -EINVAL; + + return put_user(tsk->thread.align_ctl, (unsigned long __user *)adr); +} + void __show_regs(struct pt_regs *regs) { show_regs_print_info(KERN_DEFAULT); diff --git a/arch/riscv/kernel/traps_misaligned.c b/arch/riscv/kernel/traps= _misaligned.c index d99b95084b6c..bba301b5194d 100644 --- a/arch/riscv/kernel/traps_misaligned.c +++ b/arch/riscv/kernel/traps_misaligned.c @@ -418,6 +418,9 @@ int handle_misaligned_load(struct pt_regs *regs) if (!unaligned_enabled) return -1; =20 + if (user_mode(regs) && (current->thread.align_ctl & PR_UNALIGN_SIGBUS)) + return -1; + if (get_insn(regs, epc, &insn)) return -1; =20 @@ -517,6 +520,9 @@ int handle_misaligned_store(struct pt_regs *regs) if (!unaligned_enabled) return -1; =20 + if (user_mode(regs) && (current->thread.align_ctl & PR_UNALIGN_SIGBUS)) + return -1; + if (get_insn(regs, epc, &insn)) return -1; =20 --=20 2.42.0