Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932290AbXIUWog (ORCPT ); Fri, 21 Sep 2007 18:44:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763222AbXIUWcl (ORCPT ); Fri, 21 Sep 2007 18:32:41 -0400 Received: from ns.suse.de ([195.135.220.2]:57077 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763718AbXIUWcd (ORCPT ); Fri, 21 Sep 2007 18:32:33 -0400 From: Andi Kleen References: <200709221231.836138000@suse.de> In-Reply-To: <200709221231.836138000@suse.de> To: jbeulich@novell.com, patches@x86-64.org, linux-kernel@vger.kernel.org Subject: [PATCH] [32/50] x86: Show last exception from/to register contents Message-Id: <20070921223231.DF0BA13DCD@wotan.suse.de> Date: Sat, 22 Sep 2007 00:32:31 +0200 (CEST) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10992 Lines: 353 From: "Jan Beulich" .. when dumping register state. This is particularly useful when gcc managed to tail-call optimize an indirect call which happens to hit a NULL (or otherwise invalid) pointer. The result is unreliable because interrupts happening inbetween can mess it up AK: added some warnings that the result can be unreliable Signed-off-by: Jan Beulich Signed-off-by: Andi Kleen Documentation/kernel-parameters.txt | 3 +++ arch/i386/kernel/cpu/amd.c | 4 ++++ arch/i386/kernel/cpu/common.c | 2 ++ arch/i386/kernel/cpu/intel.c | 20 ++++++++++++++------ arch/i386/kernel/traps.c | 35 +++++++++++++++++++++++++++++++++++ arch/x86_64/kernel/setup.c | 23 ++++++++++++++++++----- arch/x86_64/kernel/traps.c | 33 +++++++++++++++++++++++++++++++++ include/asm-i386/msr-index.h | 3 +++ include/asm-i386/processor.h | 4 ++++ include/asm-x86_64/msr.h | 6 ++++++ include/asm-x86_64/processor.h | 3 +++ 11 files changed, 125 insertions(+), 11 deletions(-) Index: linux/Documentation/kernel-parameters.txt =================================================================== --- linux.orig/Documentation/kernel-parameters.txt +++ linux/Documentation/kernel-parameters.txt @@ -1152,6 +1152,9 @@ and is between 256 and 4096 characters. nolapic_timer [X86-32,APIC] Do not use the local APIC timer. + noler [X86-32/X86-64] Do not print last exception records + with kernel register dumps. + noltlbs [PPC] Do not use large page/tlb entries for kernel lowmem mapping on PPC40x. Index: linux/arch/i386/kernel/cpu/amd.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/amd.c +++ linux/arch/i386/kernel/cpu/amd.c @@ -238,9 +238,13 @@ static void __cpuinit init_amd(struct cp case 0x10: case 0x11: set_bit(X86_FEATURE_K8, c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_IA32_LASTINTFROMIP; break; case 6: set_bit(X86_FEATURE_K7, c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_IA32_LASTINTFROMIP; break; } if (c->x86 >= 6) Index: linux/arch/i386/kernel/cpu/common.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/common.c +++ linux/arch/i386/kernel/cpu/common.c @@ -503,6 +503,8 @@ static void __cpuinit identify_cpu(struc /* Init Machine Check Exception if available. */ mcheck_init(c); + + ler_enable(); } void __init identify_boot_cpu(void) Index: linux/arch/i386/kernel/cpu/intel.c =================================================================== --- linux.orig/arch/i386/kernel/cpu/intel.c +++ linux/arch/i386/kernel/cpu/intel.c @@ -188,15 +188,23 @@ static void __cpuinit init_intel(struct } #endif - if (c->x86 == 15) { + switch (c->x86) { + case 15: set_bit(X86_FEATURE_P4, c->x86_capability); set_bit(X86_FEATURE_SYNC_RDTSC, c->x86_capability); - } - if (c->x86 == 6) + if (c->x86_model >= 0x03) + set_bit(X86_FEATURE_CONSTANT_TSC, c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_P4_LER_FROM_LIP; + break; + case 6: set_bit(X86_FEATURE_P3, c->x86_capability); - if ((c->x86 == 0xf && c->x86_model >= 0x03) || - (c->x86 == 0x6 && c->x86_model >= 0x0e)) - set_bit(X86_FEATURE_CONSTANT_TSC, c->x86_capability); + if (c->x86_model >= 0x0e) + set_bit(X86_FEATURE_CONSTANT_TSC, c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_IA32_LASTINTFROMIP; + break; + } if (cpu_has_ds) { unsigned int l1; Index: linux/arch/i386/kernel/traps.c =================================================================== --- linux.orig/arch/i386/kernel/traps.c +++ linux/arch/i386/kernel/traps.c @@ -374,6 +374,20 @@ void show_registers(struct pt_regs *regs unsigned int code_len = code_bytes; unsigned char c; + if (oops_in_progress && __get_cpu_var(ler_msr)) { + u32 from, to, hi; + + if (rdmsr_safe(__get_cpu_var(ler_msr), &from, &hi) == 0 + && rdmsr_safe(__get_cpu_var(ler_msr) + 1, &to, &hi) == 0) { + printk("\n" KERN_EMERG + "last branch before last exception/interrupt\n"); + printk(KERN_EMERG " from %08x", from); + print_symbol(" (%s)\n", from); + printk(KERN_EMERG " to %08x", to); + print_symbol(" (%s)", to); + } else + __get_cpu_var(ler_msr) = 0; + } printk("\n" KERN_EMERG "Stack: "); show_stack_log_lvl(NULL, regs, ®s->esp, KERN_EMERG); @@ -413,6 +427,19 @@ int is_valid_bugaddr(unsigned long eip) return ud2 == 0x0b0f; } +DEFINE_PER_CPU(u32, ler_msr); +int ler_enabled = 1; + +void ler_enable(void) { + if (__get_cpu_var(ler_msr)) { + u32 lo, hi; + + if (rdmsr_safe(MSR_IA32_DEBUGCTLMSR, &lo, &hi) < 0 + || wrmsr_safe(MSR_IA32_DEBUGCTLMSR, lo | 1, hi) < 0) + __get_cpu_var(ler_msr) = 0; + } +} + /* * This is gone through when something in the kernel has done something bad and * is about to be terminated. @@ -891,6 +918,7 @@ fastcall void __kprobes do_debug(struct struct task_struct *tsk = current; get_debugreg(condition, 6); + ler_enable(); if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, SIGTRAP) == NOTIFY_STOP) @@ -1275,6 +1303,13 @@ static int __init kstack_setup(char *s) } __setup("kstack=", kstack_setup); +static int __init ler_setup(char *s) +{ + ler_enabled = 0; + return 1; +} +__setup("noler", ler_setup); + static int __init code_bytes_setup(char *s) { code_bytes = simple_strtoul(s, NULL, 0); Index: linux/arch/x86_64/kernel/setup.c =================================================================== --- linux.orig/arch/x86_64/kernel/setup.c +++ linux/arch/x86_64/kernel/setup.c @@ -639,6 +639,9 @@ static void __cpuinit init_amd(struct cp !rdmsr_safe(MSR_VM_CR, &flags, &dummy) && (flags & 0x18)) set_bit(X86_FEATURE_VIRT_DISABLED, &c->x86_capability); + + if (ler_enabled && c->x86 <= 17) + __get_cpu_var(ler_msr) = MSR_IA32_LASTINTFROMIP; } static int enable_svm_lock(char *s) @@ -774,13 +777,22 @@ static void __cpuinit init_intel(struct c->x86_phys_bits = 36; } - if (c->x86 == 15) + switch (c->x86) { + case 15: c->x86_cache_alignment = c->x86_clflush_size * 2; - if ((c->x86 == 0xf && c->x86_model >= 0x03) || - (c->x86 == 0x6 && c->x86_model >= 0x0e)) - set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability); - if (c->x86 == 6) + if (c->x86_model >= 0x03) + set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_P4_LER_FROM_LIP; + break; + case 6: + if (c->x86_model >= 0x0e) + set_bit(X86_FEATURE_CONSTANT_TSC, &c->x86_capability); set_bit(X86_FEATURE_REP_GOOD, &c->x86_capability); + if (ler_enabled) + __get_cpu_var(ler_msr) = MSR_IA32_LASTINTFROMIP; + break; + } if (c->x86 == 15) set_bit(X86_FEATURE_SYNC_RDTSC, &c->x86_capability); else @@ -951,6 +963,7 @@ void __cpuinit identify_cpu(struct cpuin #ifdef CONFIG_NUMA numa_add_cpu(smp_processor_id()); #endif + ler_enable(); } Index: linux/arch/x86_64/kernel/traps.c =================================================================== --- linux.orig/arch/x86_64/kernel/traps.c +++ linux/arch/x86_64/kernel/traps.c @@ -492,6 +492,19 @@ void show_registers(struct pt_regs *regs * time of the fault.. */ if (in_kernel) { + if (oops_in_progress && __get_cpu_var(ler_msr)) { + u64 from, to; + + if (checking_rdmsrl(__get_cpu_var(ler_msr), from) == 0 + && checking_rdmsrl(__get_cpu_var(ler_msr) + 1, to) == 0) { + printk("last branch before last exception/interrupt\n"); + printk(" from "); + printk_address(from); + printk(" to "); + printk_address(to); + } else + __get_cpu_var(ler_msr) = 0; + } printk("Stack: "); _show_stack(NULL, regs, (unsigned long*)rsp); @@ -530,6 +543,19 @@ void out_of_line_bug(void) EXPORT_SYMBOL(out_of_line_bug); #endif +DEFINE_PER_CPU(u32, ler_msr); +int ler_enabled = 1; + +void ler_enable(void) { + if (__get_cpu_var(ler_msr)) { + u32 lo, hi; + + if (rdmsr_safe(MSR_IA32_DEBUGCTLMSR, &lo, &hi) < 0 + || wrmsr_safe(MSR_IA32_DEBUGCTLMSR, lo | 1, hi) < 0) + __get_cpu_var(ler_msr) = 0; + } +} + static DEFINE_SPINLOCK(die_lock); static int die_owner = -1; static unsigned int die_nest_count; @@ -920,6 +946,7 @@ asmlinkage void __kprobes do_debug(struc siginfo_t info; get_debugreg(condition, 6); + ler_enable(); if (notify_die(DIE_DEBUG, "debug", regs, condition, error_code, SIGTRAP) == NOTIFY_STOP) @@ -1188,6 +1215,12 @@ void __init trap_init(void) cpu_init(); } +static int __init ler_setup(char *s) +{ + ler_enabled = 0; + return 1; +} +__setup("noler", ler_setup); static int __init oops_setup(char *s) { Index: linux/include/asm-i386/msr-index.h =================================================================== --- linux.orig/include/asm-i386/msr-index.h +++ linux/include/asm-i386/msr-index.h @@ -63,6 +63,9 @@ #define MSR_IA32_LASTINTFROMIP 0x000001dd #define MSR_IA32_LASTINTTOIP 0x000001de +#define MSR_P4_LER_FROM_LIP 0x000001d7 +#define MSR_P4_LER_TO_LIP 0x000001d8 + #define MSR_IA32_MC0_CTL 0x00000400 #define MSR_IA32_MC0_STATUS 0x00000401 #define MSR_IA32_MC0_ADDR 0x00000402 Index: linux/include/asm-i386/processor.h =================================================================== --- linux.orig/include/asm-i386/processor.h +++ linux/include/asm-i386/processor.h @@ -643,6 +643,10 @@ static inline unsigned int cpuid_edx(uns return edx; } +DECLARE_PER_CPU(u32, ler_msr); +extern int ler_enabled; +void ler_enable(void); + /* generic versions from gas */ #define GENERIC_NOP1 ".byte 0x90\n" #define GENERIC_NOP2 ".byte 0x89,0xf6\n" Index: linux/include/asm-x86_64/msr.h =================================================================== --- linux.orig/include/asm-x86_64/msr.h +++ linux/include/asm-x86_64/msr.h @@ -63,6 +63,12 @@ :"c"(msr), "i"(-EIO), "0"(0)); \ ret__; }) +#define checking_rdmsrl(msr,val) ({ \ + u32 lo__, hi__; \ + int rc__ = rdmsr_safe(msr, &lo__, &hi__); \ + val = lo__ | ((u64)hi__ << 32); \ + rc__; }) + #define rdtsc(low,high) \ __asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high)) Index: linux/include/asm-x86_64/processor.h =================================================================== --- linux.orig/include/asm-x86_64/processor.h +++ linux/include/asm-x86_64/processor.h @@ -334,6 +334,9 @@ struct extended_sigtable { struct extended_signature sigs[0]; }; +DECLARE_PER_CPU(u32, ler_msr); +extern int ler_enabled; +void ler_enable(void); #define ASM_NOP1 K8_NOP1 #define ASM_NOP2 K8_NOP2 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/