diff options
Diffstat (limited to 'arch/riscv/kernel/process.c')
| -rw-r--r-- | arch/riscv/kernel/process.c | 196 |
1 files changed, 190 insertions, 6 deletions
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c index e4bc61c4e58a..a0a40889d79a 100644 --- a/arch/riscv/kernel/process.c +++ b/arch/riscv/kernel/process.c @@ -7,6 +7,7 @@ * Copyright (C) 2017 SiFive */ +#include <linux/bitfield.h> #include <linux/cpu.h> #include <linux/kernel.h> #include <linux/sched.h> @@ -15,7 +16,10 @@ #include <linux/tick.h> #include <linux/ptrace.h> #include <linux/uaccess.h> +#include <linux/personality.h> +#include <linux/entry-common.h> +#include <asm/asm-prototypes.h> #include <asm/unistd.h> #include <asm/processor.h> #include <asm/csr.h> @@ -26,6 +30,7 @@ #include <asm/cpuidle.h> #include <asm/vector.h> #include <asm/cpufeature.h> +#include <asm/exec.h> #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK) #include <linux/stackprotector.h> @@ -33,7 +38,8 @@ unsigned long __stack_chk_guard __read_mostly; EXPORT_SYMBOL(__stack_chk_guard); #endif -extern asmlinkage void ret_from_fork(void); +extern asmlinkage void ret_from_fork_kernel_asm(void); +extern asmlinkage void ret_from_fork_user_asm(void); void noinstr arch_cpu_idle(void) { @@ -54,7 +60,7 @@ 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); + return put_user(tsk->thread.align_ctl, (unsigned int __user *)adr); } void __show_regs(struct pt_regs *regs) @@ -99,6 +105,13 @@ void show_regs(struct pt_regs *regs) dump_backtrace(regs, NULL, KERN_DEFAULT); } +unsigned long arch_align_stack(unsigned long sp) +{ + if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space) + sp -= get_random_u32_below(PAGE_SIZE); + return sp & ~0xf; +} + #ifdef CONFIG_COMPAT static bool compat_mode_supported __read_mostly; @@ -171,12 +184,16 @@ void flush_thread(void) memset(¤t->thread.vstate, 0, sizeof(struct __riscv_v_ext_state)); clear_tsk_thread_flag(current, TIF_RISCV_V_DEFER_RESTORE); #endif +#ifdef CONFIG_RISCV_ISA_SUPM + if (riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM)) + envcfg_update_bits(current, ENVCFG_PMM, ENVCFG_PMM_PMLEN_0); +#endif } void arch_release_task_struct(struct task_struct *tsk) { /* Free the vector context of datap. */ - if (has_vector()) + if (has_vector() || has_xtheadvector()) riscv_v_thread_free(tsk); } @@ -192,6 +209,18 @@ int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) return 0; } +asmlinkage void ret_from_fork_kernel(void *fn_arg, int (*fn)(void *), struct pt_regs *regs) +{ + fn(fn_arg); + + syscall_exit_to_user_mode(regs); +} + +asmlinkage void ret_from_fork_user(struct pt_regs *regs) +{ + syscall_exit_to_user_mode(regs); +} + int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) { unsigned long clone_flags = args->flags; @@ -199,6 +228,10 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) unsigned long tls = args->tls; struct pt_regs *childregs = task_pt_regs(p); + /* Ensure all threads in this mm have the same pointer masking mode. */ + if (IS_ENABLED(CONFIG_RISCV_ISA_SUPM) && p->mm && (clone_flags & CLONE_VM)) + set_bit(MM_CONTEXT_LOCK_PMLEN, &p->mm->context.flags); + memset(&p->thread.s, 0, sizeof(p->thread.s)); /* p->thread holds context to be restored by __switch_to() */ @@ -210,6 +243,7 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) p->thread.s[0] = (unsigned long)args->fn; p->thread.s[1] = (unsigned long)args->fn_arg; + p->thread.ra = (unsigned long)ret_from_fork_kernel_asm; } else { *childregs = *(current_pt_regs()); /* Turn off status.VS */ @@ -219,12 +253,11 @@ int copy_thread(struct task_struct *p, const struct kernel_clone_args *args) if (clone_flags & CLONE_SETTLS) childregs->tp = tls; childregs->a0 = 0; /* Return value of fork() */ - p->thread.s[0] = 0; + p->thread.ra = (unsigned long)ret_from_fork_user_asm; } p->thread.riscv_v_flags = 0; - if (has_vector()) + if (has_vector() || has_xtheadvector()) riscv_v_thread_alloc(p); - p->thread.ra = (unsigned long)ret_from_fork; p->thread.sp = (unsigned long)childregs; /* kernel sp */ return 0; } @@ -233,3 +266,154 @@ void __init arch_task_cache_init(void) { riscv_v_setup_ctx_cache(); } + +#ifdef CONFIG_RISCV_ISA_SUPM +enum { + PMLEN_0 = 0, + PMLEN_7 = 7, + PMLEN_16 = 16, +}; + +static bool have_user_pmlen_7; +static bool have_user_pmlen_16; + +/* + * Control the relaxed ABI allowing tagged user addresses into the kernel. + */ +static unsigned int tagged_addr_disabled; + +long set_tagged_addr_ctrl(struct task_struct *task, unsigned long arg) +{ + unsigned long valid_mask = PR_PMLEN_MASK | PR_TAGGED_ADDR_ENABLE; + struct thread_info *ti = task_thread_info(task); + struct mm_struct *mm = task->mm; + unsigned long pmm; + u8 pmlen; + + if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM)) + return -EINVAL; + + if (is_compat_thread(ti)) + return -EINVAL; + + if (arg & ~valid_mask) + return -EINVAL; + + /* + * Prefer the smallest PMLEN that satisfies the user's request, + * in case choosing a larger PMLEN has a performance impact. + */ + pmlen = FIELD_GET(PR_PMLEN_MASK, arg); + if (pmlen == PMLEN_0) { + pmm = ENVCFG_PMM_PMLEN_0; + } else if (pmlen <= PMLEN_7 && have_user_pmlen_7) { + pmlen = PMLEN_7; + pmm = ENVCFG_PMM_PMLEN_7; + } else if (pmlen <= PMLEN_16 && have_user_pmlen_16) { + pmlen = PMLEN_16; + pmm = ENVCFG_PMM_PMLEN_16; + } else { + return -EINVAL; + } + + /* + * Do not allow the enabling of the tagged address ABI if globally + * disabled via sysctl abi.tagged_addr_disabled, if pointer masking + * is disabled for userspace. + */ + if (arg & PR_TAGGED_ADDR_ENABLE && (tagged_addr_disabled || !pmlen)) + return -EINVAL; + + if (!(arg & PR_TAGGED_ADDR_ENABLE)) + pmlen = PMLEN_0; + + if (mmap_write_lock_killable(mm)) + return -EINTR; + + if (test_bit(MM_CONTEXT_LOCK_PMLEN, &mm->context.flags) && mm->context.pmlen != pmlen) { + mmap_write_unlock(mm); + return -EBUSY; + } + + envcfg_update_bits(task, ENVCFG_PMM, pmm); + mm->context.pmlen = pmlen; + + mmap_write_unlock(mm); + + return 0; +} + +long get_tagged_addr_ctrl(struct task_struct *task) +{ + struct thread_info *ti = task_thread_info(task); + long ret = 0; + + if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM)) + return -EINVAL; + + if (is_compat_thread(ti)) + return -EINVAL; + + /* + * The mm context's pmlen is set only when the tagged address ABI is + * enabled, so the effective PMLEN must be extracted from envcfg.PMM. + */ + switch (task->thread.envcfg & ENVCFG_PMM) { + case ENVCFG_PMM_PMLEN_7: + ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_7); + break; + case ENVCFG_PMM_PMLEN_16: + ret = FIELD_PREP(PR_PMLEN_MASK, PMLEN_16); + break; + } + + if (task->mm->context.pmlen) + ret |= PR_TAGGED_ADDR_ENABLE; + + return ret; +} + +static bool try_to_set_pmm(unsigned long value) +{ + csr_set(CSR_ENVCFG, value); + return (csr_read_clear(CSR_ENVCFG, ENVCFG_PMM) & ENVCFG_PMM) == value; +} + +/* + * Global sysctl to disable the tagged user addresses support. This control + * only prevents the tagged address ABI enabling via prctl() and does not + * disable it for tasks that already opted in to the relaxed ABI. + */ + +static const struct ctl_table tagged_addr_sysctl_table[] = { + { + .procname = "tagged_addr_disabled", + .mode = 0644, + .data = &tagged_addr_disabled, + .maxlen = sizeof(int), + .proc_handler = proc_dointvec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, +}; + +static int __init tagged_addr_init(void) +{ + if (!riscv_has_extension_unlikely(RISCV_ISA_EXT_SUPM)) + return 0; + + /* + * envcfg.PMM is a WARL field. Detect which values are supported. + * Assume the supported PMLEN values are the same on all harts. + */ + csr_clear(CSR_ENVCFG, ENVCFG_PMM); + have_user_pmlen_7 = try_to_set_pmm(ENVCFG_PMM_PMLEN_7); + have_user_pmlen_16 = try_to_set_pmm(ENVCFG_PMM_PMLEN_16); + + if (!register_sysctl("abi", tagged_addr_sysctl_table)) + return -EINVAL; + + return 0; +} +core_initcall(tagged_addr_init); +#endif /* CONFIG_RISCV_ISA_SUPM */ |