From 034dd340b08be1f2f0477ad16131d609f9dbd53c Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 30 Aug 2026 09:22:00 -0700 Subject: Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace Pull tracing fixes from Steven Rostedt: - Fix error output of boot instance creation failure Currently if a boot instance creation fails, instead of printing out the name of the instance that failed, it prints "(null)". That is because it prints "cur_str" that had already been processed by strsep(). Print the saved name instead. While at it, print the error code of the failure. - Fix use-after-free for same named historgrams Histograms can be named so that they can be used in multiple events. But if the named histogram has a variable attached, the second event that uses the named histogram which duplicates it and needs to free the original after duplication leaves the old variable in place and still visible. If another histogram uses than variable, it will use the stale one which will try to reference the freed duplicate histogram and crash the kernel. Free the duplicate variables along with the duplicated histogram data. - Check return value of kthread_run() in event self test The events self tests uses a kthread for testing but does not check if it succeeded in creating a kthread. If the kthread creation were to fail, the code will still try to call kthread_stop() on the error returned. - Fix race between reading trace_pipe and updating subbuffer size If a user is reading the trace_pipe file at the same time they update the ring buffer sub-buffer size, can cause the trace_pipe read to read stale data. Add trace_access_lock() around updating the ring buffer sub-buffer size. - Fix eventfs_inode on failure path in creation of the events directory In the creation of the "events" directory, if after allocating the eventfs_inode a failure is detected, it calls cleanup_ei() which calls free_ei(). The free_ei() will test if eventfs_inode being freed has no children. It is a bug if it does. But on the failure case of the creation of the "events" directory, the children lists have not yet been initialized and the free will trigger a warning because list_empty() on an uninitialized list returns false. Move the initialization into init_ei() where it makes more sense and makes sure that a created eventfs_inode has its lists initialized upon creation. - Check return value of kthread_run() in ftrace direct sample code The sample code that shows how to use the ftrace direct calls does not test the return of kthread_run() to see if it succeeds. Return a failure if the kthread_run() doesn't succeed. - Clear user events state on fork in case of alloc failure On fork, the child gets a pointer to the parent's user events state. It makes a copy of it then updates the child's pointer to it. But if the allocation fails, the duplication function leaves the child with a pointer to its parent's descriptor. When the child cleans up its data, it will free the parent's descriptor while the parent is still using it. In the duplication function, set the child's user_event_mm to NULL before testing if the allocation succeeded, and when it exits it will not free the parent's descriptor. - Fix retry exhaustion in simple ring buffer reader swap simple_ring_buffer_swap_reader_page() starts with retry set to 8 and post-decrements it only after a failed link replacement. On the final attempt, a successful replacement leaves retry at zero, while a failed replacement leaves it at -1. But the check for success expects the retry value to be non-zero and exits with an error on zero. This is the opposite result. Fix it. - Fail nicely when the remote swap_reader_page() returns an error Currently, if the swap_reader_page() of a remote buffer fails, it triggers a WARN_ON_ONCE() and continues normally. Instead, have it exit with an error and a pr_warn() print instead of a full WARNING. * tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: ring-buffer: Stop remote reader update when page swap fails tracing: Fix retry exhaustion in simple ring buffer reader swap tracing/user_events: Clear copied tracing state before fork duplication samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify eventfs: Initialize ei->children and ei->list in init_ei() tracing: Fix use-after-free in trace_pipe read on sub-buffer order change tracing: Fix crash passing ERR_PTR to kthread_stop() tracing: Fix use-after-free with same-name named triggers tracing: Fix logged instance name on creation failure --- drivers/char/nvram.c | 536 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 536 insertions(+) create mode 100644 drivers/char/nvram.c (limited to 'drivers/char/nvram.c') diff --git a/drivers/char/nvram.c b/drivers/char/nvram.c new file mode 100644 index 000000000..e89cc1f1c --- /dev/null +++ b/drivers/char/nvram.c @@ -0,0 +1,536 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * CMOS/NV-RAM driver for Linux + * + * Copyright (C) 1997 Roman Hodek + * idea by and with help from Richard Jelinek + * Portions copyright (c) 2001,2002 Sun Microsystems (thockin@sun.com) + * + * This driver allows you to access the contents of the non-volatile memory in + * the mc146818rtc.h real-time clock. This chip is built into all PCs and into + * many Atari machines. In the former it's called "CMOS-RAM", in the latter + * "NVRAM" (NV stands for non-volatile). + * + * The data are supplied as a (seekable) character device, /dev/nvram. The + * size of this file is dependent on the controller. The usual size is 114, + * the number of freely available bytes in the memory (i.e., not used by the + * RTC itself). + * + * Checksums over the NVRAM contents are managed by this driver. In case of a + * bad checksum, reads and writes return -EIO. The checksum can be initialized + * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or + * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid + * again; use with care!) + * + * 1.1 Cesar Barros: SMP locking fixes + * added changelog + * 1.2 Erik Gilling: Cobalt Networks support + * Tim Hockin: general cleanup, Cobalt support + * 1.3 Wim Van Sebroeck: convert PRINT_PROC to seq_file + */ + +#define NVRAM_VERSION "1.3" + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifdef CONFIG_PPC +#include +#endif + +static DEFINE_SPINLOCK(nvram_state_lock); +static int nvram_open_cnt; /* #times opened */ +static int nvram_open_mode; /* special open modes */ +static ssize_t nvram_size; +#define NVRAM_WRITE 1 /* opened for writing (exclusive) */ +#define NVRAM_EXCL 2 /* opened with O_EXCL */ + +#ifdef CONFIG_X86 +/* + * These functions are provided to be called internally or by other parts of + * the kernel. It's up to the caller to ensure correct checksum before reading + * or after writing (needs to be done only once). + * + * It is worth noting that these functions all access bytes of general + * purpose memory in the NVRAM - that is to say, they all add the + * NVRAM_FIRST_BYTE offset. Pass them offsets into NVRAM as if you did not + * know about the RTC cruft. + */ + +#define NVRAM_BYTES (128 - NVRAM_FIRST_BYTE) + +/* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with + * rtc_lock held. Due to the index-port/data-port design of the RTC, we + * don't want two different things trying to get to it at once. (e.g. the + * periodic 11 min sync from kernel/time/ntp.c vs. this driver.) + */ + +static unsigned char __nvram_read_byte(int i) +{ + return CMOS_READ(NVRAM_FIRST_BYTE + i); +} + +static unsigned char pc_nvram_read_byte(int i) +{ + unsigned long flags; + unsigned char c; + + spin_lock_irqsave(&rtc_lock, flags); + c = __nvram_read_byte(i); + spin_unlock_irqrestore(&rtc_lock, flags); + return c; +} + +/* This races nicely with trying to read with checksum checking (nvram_read) */ +static void __nvram_write_byte(unsigned char c, int i) +{ + CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); +} + +static void pc_nvram_write_byte(unsigned char c, int i) +{ + unsigned long flags; + + spin_lock_irqsave(&rtc_lock, flags); + __nvram_write_byte(c, i); + spin_unlock_irqrestore(&rtc_lock, flags); +} + +/* On PCs, the checksum is built only over bytes 2..31 */ +#define PC_CKS_RANGE_START 2 +#define PC_CKS_RANGE_END 31 +#define PC_CKS_LOC 32 + +static int __nvram_check_checksum(void) +{ + int i; + unsigned short sum = 0; + unsigned short expect; + + for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) + sum += __nvram_read_byte(i); + expect = __nvram_read_byte(PC_CKS_LOC)<<8 | + __nvram_read_byte(PC_CKS_LOC+1); + return (sum & 0xffff) == expect; +} + +static void __nvram_set_checksum(void) +{ + int i; + unsigned short sum = 0; + + for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i) + sum += __nvram_read_byte(i); + __nvram_write_byte(sum >> 8, PC_CKS_LOC); + __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1); +} + +static long pc_nvram_set_checksum(void) +{ + spin_lock_irq(&rtc_lock); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + return 0; +} + +static long pc_nvram_initialize(void) +{ + ssize_t i; + + spin_lock_irq(&rtc_lock); + for (i = 0; i < NVRAM_BYTES; ++i) + __nvram_write_byte(0, i); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + return 0; +} + +static ssize_t pc_nvram_get_size(void) +{ + return NVRAM_BYTES; +} + +static ssize_t pc_nvram_read(char *buf, size_t count, loff_t *ppos) +{ + char *p = buf; + loff_t i; + + spin_lock_irq(&rtc_lock); + if (!__nvram_check_checksum()) { + spin_unlock_irq(&rtc_lock); + return -EIO; + } + for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) + *p = __nvram_read_byte(i); + spin_unlock_irq(&rtc_lock); + + *ppos = i; + return p - buf; +} + +static ssize_t pc_nvram_write(char *buf, size_t count, loff_t *ppos) +{ + char *p = buf; + loff_t i; + + spin_lock_irq(&rtc_lock); + if (!__nvram_check_checksum()) { + spin_unlock_irq(&rtc_lock); + return -EIO; + } + for (i = *ppos; count > 0 && i < NVRAM_BYTES; --count, ++i, ++p) + __nvram_write_byte(*p, i); + __nvram_set_checksum(); + spin_unlock_irq(&rtc_lock); + + *ppos = i; + return p - buf; +} + +const struct nvram_ops arch_nvram_ops = { + .read = pc_nvram_read, + .write = pc_nvram_write, + .read_byte = pc_nvram_read_byte, + .write_byte = pc_nvram_write_byte, + .get_size = pc_nvram_get_size, + .set_checksum = pc_nvram_set_checksum, + .initialize = pc_nvram_initialize, +}; +EXPORT_SYMBOL(arch_nvram_ops); +#endif /* CONFIG_X86 */ + +/* + * The are the file operation function for user access to /dev/nvram + */ + +static loff_t nvram_misc_llseek(struct file *file, loff_t offset, int origin) +{ + return generic_file_llseek_size(file, offset, origin, MAX_LFS_FILESIZE, + nvram_size); +} + +static ssize_t nvram_misc_read(struct file *file, char __user *buf, + size_t count, loff_t *ppos) +{ + char *tmp; + ssize_t ret; + + + if (*ppos >= nvram_size) + return 0; + + count = min_t(size_t, count, nvram_size - *ppos); + count = min_t(size_t, count, PAGE_SIZE); + + tmp = kmalloc(count, GFP_KERNEL); + if (!tmp) + return -ENOMEM; + + ret = nvram_read(tmp, count, ppos); + if (ret <= 0) + goto out; + + if (copy_to_user(buf, tmp, ret)) { + *ppos -= ret; + ret = -EFAULT; + } + +out: + kfree(tmp); + return ret; +} + +static ssize_t nvram_misc_write(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + char *tmp; + ssize_t ret; + + if (*ppos >= nvram_size) + return 0; + + count = min_t(size_t, count, nvram_size - *ppos); + count = min_t(size_t, count, PAGE_SIZE); + + tmp = memdup_user(buf, count); + if (IS_ERR(tmp)) + return PTR_ERR(tmp); + + ret = nvram_write(tmp, count, ppos); + kfree(tmp); + return ret; +} + +static long nvram_misc_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + long ret = -ENOTTY; + + switch (cmd) { +#ifdef CONFIG_PPC + case OBSOLETE_PMAC_NVRAM_GET_OFFSET: + pr_warn("nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n"); + fallthrough; + case IOC_NVRAM_GET_OFFSET: + ret = -EINVAL; +#ifdef CONFIG_PPC_PMAC + if (machine_is(powermac)) { + int part, offset; + + if (copy_from_user(&part, (void __user *)arg, + sizeof(part)) != 0) + return -EFAULT; + if (part < pmac_nvram_OF || part > pmac_nvram_NR) + return -EINVAL; + offset = pmac_get_partition(part); + if (offset < 0) + return -EINVAL; + if (copy_to_user((void __user *)arg, + &offset, sizeof(offset)) != 0) + return -EFAULT; + ret = 0; + } +#endif + break; +#ifdef CONFIG_PPC32 + case IOC_NVRAM_SYNC: + if (ppc_md.nvram_sync) + ppc_md.nvram_sync(); + ret = 0; + break; +#endif +#elif defined(CONFIG_X86) || defined(CONFIG_M68K) + case NVRAM_INIT: + /* initialize NVRAM contents and checksum */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (arch_nvram_ops.initialize) + ret = arch_nvram_ops.initialize(); + break; + case NVRAM_SETCKS: + /* just set checksum, contents unchanged (maybe useful after + * checksum garbaged somehow...) */ + if (!capable(CAP_SYS_ADMIN)) + return -EACCES; + + if (arch_nvram_ops.set_checksum) + ret = arch_nvram_ops.set_checksum(); + break; +#endif /* CONFIG_X86 || CONFIG_M68K */ + } + return ret; +} + +static int nvram_misc_open(struct inode *inode, struct file *file) +{ + spin_lock(&nvram_state_lock); + + /* Prevent multiple readers/writers if desired. */ + if ((nvram_open_cnt && (file->f_flags & O_EXCL)) || + (nvram_open_mode & NVRAM_EXCL)) { + spin_unlock(&nvram_state_lock); + return -EBUSY; + } + +#if defined(CONFIG_X86) || defined(CONFIG_M68K) + /* Prevent multiple writers if the set_checksum ioctl is implemented. */ + if ((arch_nvram_ops.set_checksum != NULL) && + (file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE)) { + spin_unlock(&nvram_state_lock); + return -EBUSY; + } +#endif + + if (file->f_flags & O_EXCL) + nvram_open_mode |= NVRAM_EXCL; + if (file->f_mode & FMODE_WRITE) + nvram_open_mode |= NVRAM_WRITE; + nvram_open_cnt++; + + spin_unlock(&nvram_state_lock); + + return 0; +} + +static int nvram_misc_release(struct inode *inode, struct file *file) +{ + spin_lock(&nvram_state_lock); + + nvram_open_cnt--; + + /* if only one instance is open, clear the EXCL bit */ + if (nvram_open_mode & NVRAM_EXCL) + nvram_open_mode &= ~NVRAM_EXCL; + if (file->f_mode & FMODE_WRITE) + nvram_open_mode &= ~NVRAM_WRITE; + + spin_unlock(&nvram_state_lock); + + return 0; +} + +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) +static const char * const floppy_types[] = { + "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M", + "3.5'' 2.88M", "3.5'' 2.88M" +}; + +static const char * const gfx_types[] = { + "EGA, VGA, ... (with BIOS)", + "CGA (40 cols)", + "CGA (80 cols)", + "monochrome", +}; + +static void pc_nvram_proc_read(unsigned char *nvram, struct seq_file *seq, + void *offset) +{ + int checksum; + int type; + + spin_lock_irq(&rtc_lock); + checksum = __nvram_check_checksum(); + spin_unlock_irq(&rtc_lock); + + seq_printf(seq, "Checksum status: %svalid\n", checksum ? "" : "not "); + + seq_printf(seq, "# floppies : %d\n", + (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0); + seq_printf(seq, "Floppy 0 type : "); + type = nvram[2] >> 4; + if (type < ARRAY_SIZE(floppy_types)) + seq_printf(seq, "%s\n", floppy_types[type]); + else + seq_printf(seq, "%d (unknown)\n", type); + seq_printf(seq, "Floppy 1 type : "); + type = nvram[2] & 0x0f; + if (type < ARRAY_SIZE(floppy_types)) + seq_printf(seq, "%s\n", floppy_types[type]); + else + seq_printf(seq, "%d (unknown)\n", type); + + seq_printf(seq, "HD 0 type : "); + type = nvram[4] >> 4; + if (type) + seq_printf(seq, "%02x\n", type == 0x0f ? nvram[11] : type); + else + seq_printf(seq, "none\n"); + + seq_printf(seq, "HD 1 type : "); + type = nvram[4] & 0x0f; + if (type) + seq_printf(seq, "%02x\n", type == 0x0f ? nvram[12] : type); + else + seq_printf(seq, "none\n"); + + seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", + nvram[18] | (nvram[19] << 8), + nvram[20], nvram[25], + nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8)); + seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n", + nvram[39] | (nvram[40] << 8), + nvram[41], nvram[46], + nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8)); + + seq_printf(seq, "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8)); + seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)\n", + nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8)); + + seq_printf(seq, "Gfx adapter : %s\n", + gfx_types[(nvram[6] >> 4) & 3]); + + seq_printf(seq, "FPU : %sinstalled\n", + (nvram[6] & 2) ? "" : "not "); + + return; +} + +static int nvram_proc_read(struct seq_file *seq, void *offset) +{ + unsigned char contents[NVRAM_BYTES]; + int i = 0; + + spin_lock_irq(&rtc_lock); + for (i = 0; i < NVRAM_BYTES; ++i) + contents[i] = __nvram_read_byte(i); + spin_unlock_irq(&rtc_lock); + + pc_nvram_proc_read(contents, seq, offset); + + return 0; +} +#endif /* CONFIG_X86 && CONFIG_PROC_FS */ + +static const struct file_operations nvram_misc_fops = { + .owner = THIS_MODULE, + .llseek = nvram_misc_llseek, + .read = nvram_misc_read, + .write = nvram_misc_write, + .unlocked_ioctl = nvram_misc_ioctl, + .open = nvram_misc_open, + .release = nvram_misc_release, +}; + +static struct miscdevice nvram_misc = { + NVRAM_MINOR, + "nvram", + &nvram_misc_fops, +}; + +static int __init nvram_module_init(void) +{ + int ret; + + nvram_size = nvram_get_size(); + if (nvram_size < 0) + return nvram_size; + + ret = misc_register(&nvram_misc); + if (ret) { + pr_err("nvram: can't misc_register on minor=%d\n", NVRAM_MINOR); + return ret; + } + +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) + if (!proc_create_single("driver/nvram", 0, NULL, nvram_proc_read)) { + pr_err("nvram: can't create /proc/driver/nvram\n"); + misc_deregister(&nvram_misc); + return -ENOMEM; + } +#endif + + pr_info("Non-volatile memory driver v" NVRAM_VERSION "\n"); + return 0; +} + +static void __exit nvram_module_exit(void) +{ +#if defined(CONFIG_X86) && defined(CONFIG_PROC_FS) + remove_proc_entry("driver/nvram", NULL); +#endif + misc_deregister(&nvram_misc); +} + +module_init(nvram_module_init); +module_exit(nvram_module_exit); + +MODULE_DESCRIPTION("CMOS/NV-RAM driver for Linux"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS_MISCDEV(NVRAM_MINOR); +MODULE_ALIAS("devname:nvram"); -- cgit v1.3.1