From 89b74cac7834734d6b2733204c639917d3826083 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu Date: Tue, 3 Mar 2020 20:24:50 +0900 Subject: tools/bootconfig: Show line and column in parse error Show line and column when we got a parse error in bootconfig tool. Current lib/bootconfig shows the parse error with byte offset, but that is not human readable. This makes xbc_init() not showing error message itself but able to pass the error message and position to caller, so that the caller can decode it and show the error message with line number and columns. With this patch, bootconfig tool shows an error with line:column as below. $ cat samples/bad-dotword.bconf # do not start keyword with . key { .word = 1 } $ ./bootconfig -a samples/bad-dotword.bconf initrd Parse Error: Invalid keyword at 3:3 Link: http://lkml.kernel.org/r/158323469002.10560.4023923847704522760.stgit@devnote2 Signed-off-by: Masami Hiramatsu Signed-off-by: Steven Rostedt (VMware) --- init/main.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) (limited to 'init/main.c') diff --git a/init/main.c b/init/main.c index ee4947af823f..e488213857e2 100644 --- a/init/main.c +++ b/init/main.c @@ -353,6 +353,8 @@ static int __init bootconfig_params(char *param, char *val, static void __init setup_boot_config(const char *cmdline) { static char tmp_cmdline[COMMAND_LINE_SIZE] __initdata; + const char *msg; + int pos; u32 size, csum; char *data, *copy; u32 *hdr; @@ -400,10 +402,14 @@ static void __init setup_boot_config(const char *cmdline) memcpy(copy, data, size); copy[size] = '\0'; - ret = xbc_init(copy); - if (ret < 0) - pr_err("Failed to parse bootconfig\n"); - else { + ret = xbc_init(copy, &msg, &pos); + if (ret < 0) { + if (pos < 0) + pr_err("Failed to init bootconfig: %s.\n", msg); + else + pr_err("Failed to parse bootconfig: %s at %d.\n", + msg, pos); + } else { pr_info("Load bootconfig: %d bytes %d nodes\n", size, ret); /* keys starting with "kernel." are passed via cmdline */ extra_command_line = xbc_make_cmdline("kernel"); -- cgit v1.2.3 From ab6f762f0f53162d41497708b33c9a3236d3609e Mon Sep 17 00:00:00 2001 From: Sergey Senozhatsky Date: Tue, 3 Mar 2020 20:30:02 +0900 Subject: printk: queue wake_up_klogd irq_work only if per-CPU areas are ready printk_deferred(), similarly to printk_safe/printk_nmi, does not immediately attempt to print a new message on the consoles, avoiding calls into non-reentrant kernel paths, e.g. scheduler or timekeeping, which potentially can deadlock the system. Those printk() flavors, instead, rely on per-CPU flush irq_work to print messages from safer contexts. For same reasons (recursive scheduler or timekeeping calls) printk() uses per-CPU irq_work in order to wake up user space syslog/kmsg readers. However, only printk_safe/printk_nmi do make sure that per-CPU areas have been initialised and that it's safe to modify per-CPU irq_work. This means that, for instance, should printk_deferred() be invoked "too early", that is before per-CPU areas are initialised, printk_deferred() will perform illegal per-CPU access. Lech Perczak [0] reports that after commit 1b710b1b10ef ("char/random: silence a lockdep splat with printk()") user-space syslog/kmsg readers are not able to read new kernel messages. The reason is printk_deferred() being called too early (as was pointed out by Petr and John). Fix printk_deferred() and do not queue per-CPU irq_work before per-CPU areas are initialized. Link: https://lore.kernel.org/lkml/aa0732c6-5c4e-8a8b-a1c1-75ebe3dca05b@camlintechnologies.com/ Reported-by: Lech Perczak Signed-off-by: Sergey Senozhatsky Tested-by: Jann Horn Reviewed-by: Petr Mladek Cc: Greg Kroah-Hartman Cc: Theodore Ts'o Cc: John Ogness Signed-off-by: Linus Torvalds --- include/linux/printk.h | 5 ----- init/main.c | 1 - kernel/printk/internal.h | 5 +++++ kernel/printk/printk.c | 34 ++++++++++++++++++++++++++++++++++ kernel/printk/printk_safe.c | 11 +---------- 5 files changed, 40 insertions(+), 16 deletions(-) (limited to 'init/main.c') diff --git a/include/linux/printk.h b/include/linux/printk.h index 1e6108b8d15f..e061635e0409 100644 --- a/include/linux/printk.h +++ b/include/linux/printk.h @@ -202,7 +202,6 @@ __printf(1, 2) void dump_stack_set_arch_desc(const char *fmt, ...); void dump_stack_print_info(const char *log_lvl); void show_regs_print_info(const char *log_lvl); extern asmlinkage void dump_stack(void) __cold; -extern void printk_safe_init(void); extern void printk_safe_flush(void); extern void printk_safe_flush_on_panic(void); #else @@ -269,10 +268,6 @@ static inline void dump_stack(void) { } -static inline void printk_safe_init(void) -{ -} - static inline void printk_safe_flush(void) { } diff --git a/init/main.c b/init/main.c index e488213857e2..a48617f2e5e5 100644 --- a/init/main.c +++ b/init/main.c @@ -913,7 +913,6 @@ asmlinkage __visible void __init start_kernel(void) boot_init_stack_canary(); time_init(); - printk_safe_init(); perf_event_init(); profile_init(); call_function_init(); diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h index c8e6ab689d42..b2b0f526f249 100644 --- a/kernel/printk/internal.h +++ b/kernel/printk/internal.h @@ -23,6 +23,9 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args); void __printk_safe_enter(void); void __printk_safe_exit(void); +void printk_safe_init(void); +bool printk_percpu_data_ready(void); + #define printk_safe_enter_irqsave(flags) \ do { \ local_irq_save(flags); \ @@ -64,4 +67,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; } #define printk_safe_enter_irq() local_irq_disable() #define printk_safe_exit_irq() local_irq_enable() +static inline void printk_safe_init(void) { } +static inline bool printk_percpu_data_ready(void) { return false; } #endif /* CONFIG_PRINTK */ diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 633f41a11d75..9a9b6156270b 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -460,6 +460,18 @@ static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); static char *log_buf = __log_buf; static u32 log_buf_len = __LOG_BUF_LEN; +/* + * We cannot access per-CPU data (e.g. per-CPU flush irq_work) before + * per_cpu_areas are initialised. This variable is set to true when + * it's safe to access per-CPU data. + */ +static bool __printk_percpu_data_ready __read_mostly; + +bool printk_percpu_data_ready(void) +{ + return __printk_percpu_data_ready; +} + /* Return log buffer address */ char *log_buf_addr_get(void) { @@ -1146,12 +1158,28 @@ static void __init log_buf_add_cpu(void) static inline void log_buf_add_cpu(void) {} #endif /* CONFIG_SMP */ +static void __init set_percpu_data_ready(void) +{ + printk_safe_init(); + /* Make sure we set this flag only after printk_safe() init is done */ + barrier(); + __printk_percpu_data_ready = true; +} + void __init setup_log_buf(int early) { unsigned long flags; char *new_log_buf; unsigned int free; + /* + * Some archs call setup_log_buf() multiple times - first is very + * early, e.g. from setup_arch(), and second - when percpu_areas + * are initialised. + */ + if (!early) + set_percpu_data_ready(); + if (log_buf != __log_buf) return; @@ -2975,6 +3003,9 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = { void wake_up_klogd(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); if (waitqueue_active(&log_wait)) { this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP); @@ -2985,6 +3016,9 @@ void wake_up_klogd(void) void defer_console_output(void) { + if (!printk_percpu_data_ready()) + return; + preempt_disable(); __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT); irq_work_queue(this_cpu_ptr(&wake_up_klogd_work)); diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c index b4045e782743..d9a659a686f3 100644 --- a/kernel/printk/printk_safe.c +++ b/kernel/printk/printk_safe.c @@ -27,7 +27,6 @@ * There are situations when we want to make sure that all buffers * were handled or when IRQs are blocked. */ -static int printk_safe_irq_ready __read_mostly; #define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \ sizeof(atomic_t) - \ @@ -51,7 +50,7 @@ static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq); /* Get flushed in a more safe context. */ static void queue_flush_work(struct printk_safe_seq_buf *s) { - if (printk_safe_irq_ready) + if (printk_percpu_data_ready()) irq_work_queue(&s->work); } @@ -402,14 +401,6 @@ void __init printk_safe_init(void) #endif } - /* - * In the highly unlikely event that a NMI were to trigger at - * this moment. Make sure IRQ work is set up before this - * variable is set. - */ - barrier(); - printk_safe_irq_ready = 1; - /* Flush pending messages that did not have scheduled IRQ works. */ printk_safe_flush(); } -- cgit v1.2.3