From 6909e29fdefbb7aa643021279daef6ed10c81528 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Thu, 12 Oct 2017 16:06:11 +0200 Subject: kdb: use __ktime_get_real_seconds instead of __current_kernel_time kdb is the only user of the __current_kernel_time() interface, which is not y2038 safe and should be removed at some point. The kdb code also goes to great lengths to print the time in a human-readable format from 'struct timespec', again using a non-y2038-safe re-implementation of the generic time_to_tm() code. Using __current_kernel_time() here is necessary since the regular accessors that require a sequence lock might hang when called during the xtime update. However, this is safe in the particular case since kdb is only interested in the tv_sec field that is updated atomically. In order to make this y2038-safe, I'm converting the code to the generic time64_to_tm helper, but that introduces the problem that we have no interface like __current_kernel_time() that provides a 64-bit timestamp in a lockless, safe and architecture-independent way. I have multiple ideas for how to solve that: - __ktime_get_real_seconds() is lockless, but can return incorrect results on 32-bit architectures in the special case that we are in the process of changing the time across the epoch, either during the timer tick that overflows the seconds in 2038, or while calling settimeofday. - ktime_get_real_fast_ns() would work in this context, but does require a call into the clocksource driver to return a high-resolution timestamp. This may have undesired side-effects in the debugger, since we want to limit the interactions with the rest of the kernel. - Adding a ktime_get_real_fast_seconds() based on tk_fast_mono plus tkr->base_real without the tk_clock_read() delta. Not sure about the value of adding yet another interface here. - Changing the existing ktime_get_real_seconds() to use tk_fast_mono on 32-bit architectures rather than xtime_sec. I think this could work, but am not entirely sure if this is an improvement. I picked the first of those for simplicity here. It's technically not correct but probably good enough as the time is only used for the debugging output and the race will likely never be hit in practice. Another downside is having to move the declaration into a public header file. Let me know if anyone has a different preference. Cc: Andy Shevchenko Link: https://patchwork.kernel.org/patch/9775309/ Signed-off-by: Arnd Bergmann Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_main.c | 45 +++++---------------------------------------- 1 file changed, 5 insertions(+), 40 deletions(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index c8146d53ca67..69e70f4021fe 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -2479,41 +2479,6 @@ static int kdb_kill(int argc, const char **argv) return 0; } -struct kdb_tm { - int tm_sec; /* seconds */ - int tm_min; /* minutes */ - int tm_hour; /* hours */ - int tm_mday; /* day of the month */ - int tm_mon; /* month */ - int tm_year; /* year */ -}; - -static void kdb_gmtime(struct timespec *tv, struct kdb_tm *tm) -{ - /* This will work from 1970-2099, 2100 is not a leap year */ - static int mon_day[] = { 31, 29, 31, 30, 31, 30, 31, - 31, 30, 31, 30, 31 }; - memset(tm, 0, sizeof(*tm)); - tm->tm_sec = tv->tv_sec % (24 * 60 * 60); - tm->tm_mday = tv->tv_sec / (24 * 60 * 60) + - (2 * 365 + 1); /* shift base from 1970 to 1968 */ - tm->tm_min = tm->tm_sec / 60 % 60; - tm->tm_hour = tm->tm_sec / 60 / 60; - tm->tm_sec = tm->tm_sec % 60; - tm->tm_year = 68 + 4*(tm->tm_mday / (4*365+1)); - tm->tm_mday %= (4*365+1); - mon_day[1] = 29; - while (tm->tm_mday >= mon_day[tm->tm_mon]) { - tm->tm_mday -= mon_day[tm->tm_mon]; - if (++tm->tm_mon == 12) { - tm->tm_mon = 0; - ++tm->tm_year; - mon_day[1] = 28; - } - } - ++tm->tm_mday; -} - /* * Most of this code has been lifted from kernel/timer.c::sys_sysinfo(). * I cannot call that code directly from kdb, it has an unconditional @@ -2539,8 +2504,8 @@ static void kdb_sysinfo(struct sysinfo *val) */ static int kdb_summary(int argc, const char **argv) { - struct timespec now; - struct kdb_tm tm; + time64_t now; + struct tm tm; struct sysinfo val; if (argc) @@ -2554,9 +2519,9 @@ static int kdb_summary(int argc, const char **argv) kdb_printf("domainname %s\n", init_uts_ns.name.domainname); kdb_printf("ccversion %s\n", __stringify(CCVERSION)); - now = __current_kernel_time(); - kdb_gmtime(&now, &tm); - kdb_printf("date %04d-%02d-%02d %02d:%02d:%02d " + now = __ktime_get_real_seconds(); + time64_to_tm(now, 0, &tm); + kdb_printf("date %04ld-%02d-%02d %02d:%02d:%02d " "tz_minuteswest %d\n", 1900+tm.tm_year, tm.tm_mon+1, tm.tm_mday, tm.tm_hour, tm.tm_min, tm.tm_sec, -- cgit v1.2.3 From 1e0ce03bf142454f38a5fc050bf4fd698d2d36d8 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 8 Dec 2017 10:19:19 -0800 Subject: kdb: make "mdr" command repeat The "mdr" command should repeat (continue) when only Enter/Return is pressed, so make it do so. Signed-off-by: Randy Dunlap Cc: Daniel Thompson Cc: Jason Wessel Cc: kgdb-bugreport@lists.sourceforge.net Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_main.c | 27 +++++++++++++++++++++------ 1 file changed, 21 insertions(+), 6 deletions(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 69e70f4021fe..ff6047d3b73f 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -1566,6 +1566,7 @@ static int kdb_md(int argc, const char **argv) int symbolic = 0; int valid = 0; int phys = 0; + int raw = 0; kdbgetintenv("MDCOUNT", &mdcount); kdbgetintenv("RADIX", &radix); @@ -1575,9 +1576,10 @@ static int kdb_md(int argc, const char **argv) repeat = mdcount * 16 / bytesperword; if (strcmp(argv[0], "mdr") == 0) { - if (argc != 2) + if (argc == 2 || (argc == 0 && last_addr != 0)) + valid = raw = 1; + else return KDB_ARGCOUNT; - valid = 1; } else if (isdigit(argv[0][2])) { bytesperword = (int)(argv[0][2] - '0'); if (bytesperword == 0) { @@ -1613,7 +1615,10 @@ static int kdb_md(int argc, const char **argv) radix = last_radix; bytesperword = last_bytesperword; repeat = last_repeat; - mdcount = ((repeat * bytesperword) + 15) / 16; + if (raw) + mdcount = repeat; + else + mdcount = ((repeat * bytesperword) + 15) / 16; } if (argc) { @@ -1630,7 +1635,10 @@ static int kdb_md(int argc, const char **argv) diag = kdbgetularg(argv[nextarg], &val); if (!diag) { mdcount = (int) val; - repeat = mdcount * 16 / bytesperword; + if (raw) + repeat = mdcount; + else + repeat = mdcount * 16 / bytesperword; } } if (argc >= nextarg+1) { @@ -1640,8 +1648,15 @@ static int kdb_md(int argc, const char **argv) } } - if (strcmp(argv[0], "mdr") == 0) - return kdb_mdr(addr, mdcount); + if (strcmp(argv[0], "mdr") == 0) { + int ret; + last_addr = addr; + ret = kdb_mdr(addr, mdcount); + last_addr += mdcount; + last_repeat = mdcount; + last_bytesperword = bytesperword; // to make REPEAT happy + return ret; + } switch (radix) { case 10: -- cgit v1.2.3 From b0f73bc7f1793997eb48bd14e3db51c3c95e2098 Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 8 Dec 2017 10:19:23 -0800 Subject: kdb: drop newline in unknown command output When an unknown command is entered, kdb prints "Unknown kdb command:" and then the unknown text, including the newline character. This causes the ending single-quote mark to be printed on the next line by itself, so just change the ending newline character to a null character (end of string) so that it won't be "printed." Signed-off-by: Randy Dunlap Cc: Daniel Thompson Cc: Jason Wessel Cc: kgdb-bugreport@lists.sourceforge.net Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_main.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index ff6047d3b73f..6055231544a0 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -1150,6 +1150,16 @@ void kdb_set_current_task(struct task_struct *p) kdb_current_regs = NULL; } +static void drop_newline(char *buf) +{ + size_t len = strlen(buf); + + if (len == 0) + return; + if (*(buf + len - 1) == '\n') + *(buf + len - 1) = '\0'; +} + /* * kdb_local - The main code for kdb. This routine is invoked on a * specific processor, it is not global. The main kdb() routine @@ -1327,6 +1337,7 @@ do_full_getstr: cmdptr = cmd_head; diag = kdb_parse(cmdbuf); if (diag == KDB_NOTFOUND) { + drop_newline(cmdbuf); kdb_printf("Unknown kdb command: '%s'\n", cmdbuf); diag = 0; } -- cgit v1.2.3 From 33f765f698895527acd69faf5d54ab07f02683ff Mon Sep 17 00:00:00 2001 From: Randy Dunlap Date: Fri, 8 Dec 2017 10:19:28 -0800 Subject: kdb: bl: don't use tab character in output The "bl" (list breakpoints) command prints a '\t' (tab) character in its output, but on a console (video device), that just prints some odd graphics character. Instead of printing a tab character, just align the output with spaces. Signed-off-by: Randy Dunlap Cc: Daniel Thompson Cc: Jason Wessel Cc: kgdb-bugreport@lists.sourceforge.net Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_bp.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_bp.c b/kernel/debug/kdb/kdb_bp.c index 90ff129c88a2..62c301ad0773 100644 --- a/kernel/debug/kdb/kdb_bp.c +++ b/kernel/debug/kdb/kdb_bp.c @@ -242,11 +242,11 @@ static void kdb_printbp(kdb_bp_t *bp, int i) kdb_symbol_print(bp->bp_addr, NULL, KDB_SP_DEFAULT); if (bp->bp_enabled) - kdb_printf("\n is enabled"); + kdb_printf("\n is enabled "); else kdb_printf("\n is disabled"); - kdb_printf("\taddr at %016lx, hardtype=%d installed=%d\n", + kdb_printf(" addr at %016lx, hardtype=%d installed=%d\n", bp->bp_addr, bp->bp_type, bp->bp_installed); kdb_printf("\n"); -- cgit v1.2.3 From 40b90efeae9be8702d387dbcbb3aadc57033d4db Mon Sep 17 00:00:00 2001 From: Baolin Wang Date: Mon, 29 Jan 2018 10:22:51 +0800 Subject: kdb: use ktime_get_mono_fast_ns() instead of ktime_get_ts() The kdb code will print the monotonic time by ktime_get_ts(), but the ktime_get_ts() will be protected by a sequence lock, that will introduce one deadlock risk if the lock was already held in the context from which we entered the debugger. Thus we can use the ktime_get_mono_fast_ns() to get the monotonic time, which is NMI safe access to clock monotonic. Moreover we can remove the 'struct timespec', which is not y2038 safe. Signed-off-by: Baolin Wang Reviewed-by: Daniel Thompson Reviewed-by: Arnd Bergmann Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c index 6055231544a0..16140d1aa0c3 100644 --- a/kernel/debug/kdb/kdb_main.c +++ b/kernel/debug/kdb/kdb_main.c @@ -2512,10 +2512,10 @@ static int kdb_kill(int argc, const char **argv) */ static void kdb_sysinfo(struct sysinfo *val) { - struct timespec uptime; - ktime_get_ts(&uptime); + u64 uptime = ktime_get_mono_fast_ns(); + memset(val, 0, sizeof(*val)); - val->uptime = uptime.tv_sec; + val->uptime = div_u64(uptime, NSEC_PER_SEC); val->loads[0] = avenrun[0]; val->loads[1] = avenrun[1]; val->loads[2] = avenrun[2]; -- cgit v1.2.3 From 2cf2f0d5b91fd1b06a6ae260462fc7945ea84add Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 2 Feb 2018 15:59:40 +0100 Subject: kdb: use memmove instead of overlapping memcpy gcc discovered that the memcpy() arguments in kdbnearsym() overlap, so we should really use memmove(), which is defined to handle that correctly: In function 'memcpy', inlined from 'kdbnearsym' at /git/arm-soc/kernel/debug/kdb/kdb_support.c:132:4: /git/arm-soc/include/linux/string.h:353:9: error: '__builtin_memcpy' accessing 792 bytes at offsets 0 and 8 overlaps 784 bytes at offset 8 [-Werror=restrict] return __builtin_memcpy(p, q, size); Signed-off-by: Arnd Bergmann Signed-off-by: Jason Wessel --- kernel/debug/kdb/kdb_support.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/debug') diff --git a/kernel/debug/kdb/kdb_support.c b/kernel/debug/kdb/kdb_support.c index d35cc2d3a4cc..990b3cc526c8 100644 --- a/kernel/debug/kdb/kdb_support.c +++ b/kernel/debug/kdb/kdb_support.c @@ -129,13 +129,13 @@ int kdbnearsym(unsigned long addr, kdb_symtab_t *symtab) } if (i >= ARRAY_SIZE(kdb_name_table)) { debug_kfree(kdb_name_table[0]); - memcpy(kdb_name_table, kdb_name_table+1, + memmove(kdb_name_table, kdb_name_table+1, sizeof(kdb_name_table[0]) * (ARRAY_SIZE(kdb_name_table)-1)); } else { debug_kfree(knt1); knt1 = kdb_name_table[i]; - memcpy(kdb_name_table+i, kdb_name_table+i+1, + memmove(kdb_name_table+i, kdb_name_table+i+1, sizeof(kdb_name_table[0]) * (ARRAY_SIZE(kdb_name_table)-i-1)); } -- cgit v1.2.3