From fd07f802a70935fbbfb9cc2d11e1d8ac95f28e44 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 29 Jun 2020 15:48:45 +0100 Subject: x86/dumpstack: Add log_lvl to show_iret_regs() show_trace_log_lvl() provides x86 platform-specific way to unwind backtrace with a given log level. Unfortunately, registers dump(s) are not printed with the same log level - instead, KERN_DEFAULT is always used. Arista's switches uses quite common setup with rsyslog, where only urgent messages goes to console (console_log_level=KERN_ERR), everything else goes into /var/log/ as the console baud-rate often is indecently slow (9600 bps). Backtrace dumps without registers printed have proven to be as useful as morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED (which I believe is still the most elegant way to fix raciness of sysrq[1]) the log level should be passed down the stack to register dumping functions. Besides, there is a potential use-case for printing traces with KERN_DEBUG level [2] (where registers dump shouldn't appear with higher log level). Add log_lvl parameter to show_iret_regs() as a preparation to add it to __show_regs() and show_regs_if_on_stack(). [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/ [2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/ Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Acked-by: Petr Mladek Link: https://lkml.kernel.org/r/20200629144847.492794-2-dima@arista.com --- arch/x86/include/asm/kdebug.h | 2 +- arch/x86/kernel/dumpstack.c | 8 ++++---- arch/x86/kernel/process_64.c | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) (limited to 'arch') diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h index 247ab14c6309..da024bbda6f4 100644 --- a/arch/x86/include/asm/kdebug.h +++ b/arch/x86/include/asm/kdebug.h @@ -37,7 +37,7 @@ void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr); extern int __must_check __die(const char *, struct pt_regs *, long); extern void show_stack_regs(struct pt_regs *regs); extern void __show_regs(struct pt_regs *regs, enum show_regs_mode); -extern void show_iret_regs(struct pt_regs *regs); +extern void show_iret_regs(struct pt_regs *regs, const char *log_lvl); extern unsigned long oops_begin(void); extern void oops_end(unsigned long, struct pt_regs *, int signr); diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index b037cfa7c0c5..c36d629a25a8 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -126,10 +126,10 @@ void show_ip(struct pt_regs *regs, const char *loglvl) show_opcodes(regs, loglvl); } -void show_iret_regs(struct pt_regs *regs) +void show_iret_regs(struct pt_regs *regs, const char *log_lvl) { - show_ip(regs, KERN_DEFAULT); - printk(KERN_DEFAULT "RSP: %04x:%016lx EFLAGS: %08lx", (int)regs->ss, + show_ip(regs, log_lvl); + printk("%sRSP: %04x:%016lx EFLAGS: %08lx", log_lvl, (int)regs->ss, regs->sp, regs->flags); } @@ -155,7 +155,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * full pt_regs might not have been saved yet. In that case * just print the iret frame. */ - show_iret_regs(regs); + show_iret_regs(regs, KERN_DEFAULT); } } diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 9a97415b2139..09bcb296cda6 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -69,7 +69,7 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) unsigned int fsindex, gsindex; unsigned int ds, es; - show_iret_regs(regs); + show_iret_regs(regs, KERN_DEFAULT); if (regs->orig_ax != -1) pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax); -- cgit v1.2.3-70-g09d2 From 44e215352cf17333992d56941b5bf4af60a67609 Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 29 Jun 2020 15:48:46 +0100 Subject: x86/dumpstack: Add log_lvl to __show_regs() show_trace_log_lvl() provides x86 platform-specific way to unwind backtrace with a given log level. Unfortunately, registers dump(s) are not printed with the same log level - instead, KERN_DEFAULT is always used. Arista's switches uses quite common setup with rsyslog, where only urgent messages goes to console (console_log_level=KERN_ERR), everything else goes into /var/log/ as the console baud-rate often is indecently slow (9600 bps). Backtrace dumps without registers printed have proven to be as useful as morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED (which I believe is still the most elegant way to fix raciness of sysrq[1]) the log level should be passed down the stack to register dumping functions. Besides, there is a potential use-case for printing traces with KERN_DEBUG level [2] (where registers dump shouldn't appear with higher log level). Add log_lvl parameter to __show_regs(). Keep the used log level intact to separate visible change. [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/ [2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/ Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Acked-by: Petr Mladek Link: https://lkml.kernel.org/r/20200629144847.492794-3-dima@arista.com --- arch/x86/include/asm/kdebug.h | 3 ++- arch/x86/kernel/dumpstack.c | 9 +++++--- arch/x86/kernel/process_32.c | 29 ++++++++++++------------ arch/x86/kernel/process_64.c | 51 ++++++++++++++++++++++--------------------- 4 files changed, 49 insertions(+), 43 deletions(-) (limited to 'arch') diff --git a/arch/x86/include/asm/kdebug.h b/arch/x86/include/asm/kdebug.h index da024bbda6f4..d1514e70477b 100644 --- a/arch/x86/include/asm/kdebug.h +++ b/arch/x86/include/asm/kdebug.h @@ -36,7 +36,8 @@ extern void die(const char *, struct pt_regs *,long); void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr); extern int __must_check __die(const char *, struct pt_regs *, long); extern void show_stack_regs(struct pt_regs *regs); -extern void __show_regs(struct pt_regs *regs, enum show_regs_mode); +extern void __show_regs(struct pt_regs *regs, enum show_regs_mode, + const char *log_lvl); extern void show_iret_regs(struct pt_regs *regs, const char *log_lvl); extern unsigned long oops_begin(void); extern void oops_end(unsigned long, struct pt_regs *, int signr); diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index c36d629a25a8..4954d6678cef 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -146,7 +146,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * they can be printed in the right context. */ if (!partial && on_stack(info, regs, sizeof(*regs))) { - __show_regs(regs, SHOW_REGS_SHORT); + __show_regs(regs, SHOW_REGS_SHORT, KERN_DEFAULT); } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET, IRET_FRAME_SIZE)) { @@ -345,7 +345,7 @@ void oops_end(unsigned long flags, struct pt_regs *regs, int signr) oops_exit(); /* Executive summary in case the oops scrolled away */ - __show_regs(&exec_summary_regs, SHOW_REGS_ALL); + __show_regs(&exec_summary_regs, SHOW_REGS_ALL, KERN_DEFAULT); if (!signr) return; @@ -437,9 +437,12 @@ void die_addr(const char *str, struct pt_regs *regs, long err, long gp_addr) void show_regs(struct pt_regs *regs) { + enum show_regs_mode print_kernel_regs; + show_regs_print_info(KERN_DEFAULT); - __show_regs(regs, user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL); + print_kernel_regs = user_mode(regs) ? SHOW_REGS_USER : SHOW_REGS_ALL; + __show_regs(regs, print_kernel_regs, KERN_DEFAULT); /* * When in-kernel, we also print out the stack at the time of the fault.. diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c index acfd6d2a0cbf..4f2f54e1281c 100644 --- a/arch/x86/kernel/process_32.c +++ b/arch/x86/kernel/process_32.c @@ -56,7 +56,8 @@ #include "process.h" -void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) +void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, + const char *log_lvl) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; unsigned long d0, d1, d2, d3, d6, d7; @@ -67,14 +68,14 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) else savesegment(gs, gs); - show_ip(regs, KERN_DEFAULT); + show_ip(regs, log_lvl); - printk(KERN_DEFAULT "EAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", - regs->ax, regs->bx, regs->cx, regs->dx); - printk(KERN_DEFAULT "ESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", - regs->si, regs->di, regs->bp, regs->sp); - printk(KERN_DEFAULT "DS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n", - (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, regs->ss, regs->flags); + printk("%sEAX: %08lx EBX: %08lx ECX: %08lx EDX: %08lx\n", + log_lvl, regs->ax, regs->bx, regs->cx, regs->dx); + printk("%sESI: %08lx EDI: %08lx EBP: %08lx ESP: %08lx\n", + log_lvl, regs->si, regs->di, regs->bp, regs->sp); + printk("%sDS: %04x ES: %04x FS: %04x GS: %04x SS: %04x EFLAGS: %08lx\n", + log_lvl, (u16)regs->ds, (u16)regs->es, (u16)regs->fs, gs, regs->ss, regs->flags); if (mode != SHOW_REGS_ALL) return; @@ -83,8 +84,8 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) cr2 = read_cr2(); cr3 = __read_cr3(); cr4 = __read_cr4(); - printk(KERN_DEFAULT "CR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", - cr0, cr2, cr3, cr4); + printk("%sCR0: %08lx CR2: %08lx CR3: %08lx CR4: %08lx\n", + log_lvl, cr0, cr2, cr3, cr4); get_debugreg(d0, 0); get_debugreg(d1, 1); @@ -98,10 +99,10 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) (d6 == DR6_RESERVED) && (d7 == 0x400)) return; - printk(KERN_DEFAULT "DR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", - d0, d1, d2, d3); - printk(KERN_DEFAULT "DR6: %08lx DR7: %08lx\n", - d6, d7); + printk("%sDR0: %08lx DR1: %08lx DR2: %08lx DR3: %08lx\n", + log_lvl, d0, d1, d2, d3); + printk("%sDR6: %08lx DR7: %08lx\n", + log_lvl, d6, d7); } void release_thread(struct task_struct *dead_task) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 09bcb296cda6..04d201ad3a1e 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -62,30 +62,31 @@ #include "process.h" /* Prints also some state that isn't saved in the pt_regs */ -void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) +void __show_regs(struct pt_regs *regs, enum show_regs_mode mode, + const char *log_lvl) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L, fs, gs, shadowgs; unsigned long d0, d1, d2, d3, d6, d7; unsigned int fsindex, gsindex; unsigned int ds, es; - show_iret_regs(regs, KERN_DEFAULT); + show_iret_regs(regs, log_lvl); if (regs->orig_ax != -1) pr_cont(" ORIG_RAX: %016lx\n", regs->orig_ax); else pr_cont("\n"); - printk(KERN_DEFAULT "RAX: %016lx RBX: %016lx RCX: %016lx\n", - regs->ax, regs->bx, regs->cx); - printk(KERN_DEFAULT "RDX: %016lx RSI: %016lx RDI: %016lx\n", - regs->dx, regs->si, regs->di); - printk(KERN_DEFAULT "RBP: %016lx R08: %016lx R09: %016lx\n", - regs->bp, regs->r8, regs->r9); - printk(KERN_DEFAULT "R10: %016lx R11: %016lx R12: %016lx\n", - regs->r10, regs->r11, regs->r12); - printk(KERN_DEFAULT "R13: %016lx R14: %016lx R15: %016lx\n", - regs->r13, regs->r14, regs->r15); + printk("%sRAX: %016lx RBX: %016lx RCX: %016lx\n", + log_lvl, regs->ax, regs->bx, regs->cx); + printk("%sRDX: %016lx RSI: %016lx RDI: %016lx\n", + log_lvl, regs->dx, regs->si, regs->di); + printk("%sRBP: %016lx R08: %016lx R09: %016lx\n", + log_lvl, regs->bp, regs->r8, regs->r9); + printk("%sR10: %016lx R11: %016lx R12: %016lx\n", + log_lvl, regs->r10, regs->r11, regs->r12); + printk("%sR13: %016lx R14: %016lx R15: %016lx\n", + log_lvl, regs->r13, regs->r14, regs->r15); if (mode == SHOW_REGS_SHORT) return; @@ -93,8 +94,8 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) if (mode == SHOW_REGS_USER) { rdmsrl(MSR_FS_BASE, fs); rdmsrl(MSR_KERNEL_GS_BASE, shadowgs); - printk(KERN_DEFAULT "FS: %016lx GS: %016lx\n", - fs, shadowgs); + printk("%sFS: %016lx GS: %016lx\n", + log_lvl, fs, shadowgs); return; } @@ -112,12 +113,12 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) cr3 = __read_cr3(); cr4 = __read_cr4(); - printk(KERN_DEFAULT "FS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", - fs, fsindex, gs, gsindex, shadowgs); - printk(KERN_DEFAULT "CS: %04lx DS: %04x ES: %04x CR0: %016lx\n", regs->cs, ds, - es, cr0); - printk(KERN_DEFAULT "CR2: %016lx CR3: %016lx CR4: %016lx\n", cr2, cr3, - cr4); + printk("%sFS: %016lx(%04x) GS:%016lx(%04x) knlGS:%016lx\n", + log_lvl, fs, fsindex, gs, gsindex, shadowgs); + printk("%sCS: %04lx DS: %04x ES: %04x CR0: %016lx\n", + log_lvl, regs->cs, ds, es, cr0); + printk("%sCR2: %016lx CR3: %016lx CR4: %016lx\n", + log_lvl, cr2, cr3, cr4); get_debugreg(d0, 0); get_debugreg(d1, 1); @@ -129,14 +130,14 @@ void __show_regs(struct pt_regs *regs, enum show_regs_mode mode) /* Only print out debug registers if they are in their non-default state. */ if (!((d0 == 0) && (d1 == 0) && (d2 == 0) && (d3 == 0) && (d6 == DR6_RESERVED) && (d7 == 0x400))) { - printk(KERN_DEFAULT "DR0: %016lx DR1: %016lx DR2: %016lx\n", - d0, d1, d2); - printk(KERN_DEFAULT "DR3: %016lx DR6: %016lx DR7: %016lx\n", - d3, d6, d7); + printk("%sDR0: %016lx DR1: %016lx DR2: %016lx\n", + log_lvl, d0, d1, d2); + printk("%sDR3: %016lx DR6: %016lx DR7: %016lx\n", + log_lvl, d3, d6, d7); } if (boot_cpu_has(X86_FEATURE_OSPKE)) - printk(KERN_DEFAULT "PKRU: %08x\n", read_pkru()); + printk("%sPKRU: %08x\n", log_lvl, read_pkru()); } void release_thread(struct task_struct *dead_task) -- cgit v1.2.3-70-g09d2 From ef2ff0f5d6008d325c9a068e20981c0d0acc4d6b Mon Sep 17 00:00:00 2001 From: Dmitry Safonov Date: Mon, 29 Jun 2020 15:48:47 +0100 Subject: x86/dumpstack: Show registers dump with trace's log level show_trace_log_lvl() provides x86 platform-specific way to unwind backtrace with a given log level. Unfortunately, registers dump(s) are not printed with the same log level - instead, KERN_DEFAULT is always used. Arista's switches uses quite common setup with rsyslog, where only urgent messages goes to console (console_log_level=KERN_ERR), everything else goes into /var/log/ as the console baud-rate often is indecently slow (9600 bps). Backtrace dumps without registers printed have proven to be as useful as morning standups. Furthermore, in order to introduce KERN_UNSUPPRESSED (which I believe is still the most elegant way to fix raciness of sysrq[1]) the log level should be passed down the stack to register dumping functions. Besides, there is a potential use-case for printing traces with KERN_DEBUG level [2] (where registers dump shouldn't appear with higher log level). After all preparations are done, provide log_lvl parameter for show_regs_if_on_stack() and wire up to actual log level used as an argument for show_trace_log_lvl(). [1]: https://lore.kernel.org/lkml/20190528002412.1625-1-dima@arista.com/ [2]: https://lore.kernel.org/linux-doc/20190724170249.9644-1-dima@arista.com/ Signed-off-by: Dmitry Safonov Signed-off-by: Thomas Gleixner Acked-by: Petr Mladek Link: https://lkml.kernel.org/r/20200629144847.492794-4-dima@arista.com --- arch/x86/kernel/dumpstack.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'arch') diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c index 4954d6678cef..f9a3526af15d 100644 --- a/arch/x86/kernel/dumpstack.c +++ b/arch/x86/kernel/dumpstack.c @@ -134,7 +134,7 @@ void show_iret_regs(struct pt_regs *regs, const char *log_lvl) } static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, - bool partial) + bool partial, const char *log_lvl) { /* * These on_stack() checks aren't strictly necessary: the unwind code @@ -146,7 +146,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * they can be printed in the right context. */ if (!partial && on_stack(info, regs, sizeof(*regs))) { - __show_regs(regs, SHOW_REGS_SHORT, KERN_DEFAULT); + __show_regs(regs, SHOW_REGS_SHORT, log_lvl); } else if (partial && on_stack(info, (void *)regs + IRET_FRAME_OFFSET, IRET_FRAME_SIZE)) { @@ -155,7 +155,7 @@ static void show_regs_if_on_stack(struct stack_info *info, struct pt_regs *regs, * full pt_regs might not have been saved yet. In that case * just print the iret frame. */ - show_iret_regs(regs, KERN_DEFAULT); + show_iret_regs(regs, log_lvl); } } @@ -210,7 +210,7 @@ void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs, printk("%s <%s>\n", log_lvl, stack_name); if (regs) - show_regs_if_on_stack(&stack_info, regs, partial); + show_regs_if_on_stack(&stack_info, regs, partial, log_lvl); /* * Scan the stack, printing any text addresses we find. At the @@ -271,7 +271,7 @@ next: /* if the frame has entry regs, print them */ regs = unwind_get_entry_regs(&state, &partial); if (regs) - show_regs_if_on_stack(&stack_info, regs, partial); + show_regs_if_on_stack(&stack_info, regs, partial, log_lvl); } if (stack_name) -- cgit v1.2.3-70-g09d2