From 4d067d8e056d76a3327f0517c7722db55e7888fc Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Thu, 9 May 2013 12:02:29 +0200 Subject: x86: Extend #DF debugging aid to 64-bit It is sometimes very helpful to be able to pinpoint the location which causes a double fault before it turns into a triple fault and the machine reboots. We have this for 32-bit already so extend it to 64-bit. On 64-bit we get the register snapshot at #DF time and not from the first exception which actually causes the #DF. It should be close enough, though. [ hpa: and definitely better than nothing, which is what we have now. ] Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/1368093749-31296-1-git-send-email-bp@alien8.de Signed-off-by: H. Peter Anvin --- arch/x86/Kconfig.debug | 1 - arch/x86/include/asm/processor.h | 2 +- arch/x86/kernel/Makefile | 2 +- arch/x86/kernel/doublefault.c | 84 ++++++++++++++++++++++++++++++++++++++++ arch/x86/kernel/doublefault_32.c | 69 --------------------------------- arch/x86/kernel/traps.c | 3 ++ 6 files changed, 89 insertions(+), 72 deletions(-) create mode 100644 arch/x86/kernel/doublefault.c delete mode 100644 arch/x86/kernel/doublefault_32.c diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug index c198b7e13e7b..b6a770132b67 100644 --- a/arch/x86/Kconfig.debug +++ b/arch/x86/Kconfig.debug @@ -122,7 +122,6 @@ config DEBUG_NX_TEST config DOUBLEFAULT default y bool "Enable doublefault exception handler" if EXPERT - depends on X86_32 ---help--- This option allows trapping of rare doublefault exceptions that would otherwise cause a system to silently reboot. Disabling this diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 22224b3b43bb..5b87d52eed0b 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -981,5 +981,5 @@ bool xen_set_default_idle(void); #endif void stop_this_cpu(void *dummy); - +void df_debug(struct pt_regs *regs, long error_code); #endif /* _ASM_X86_PROCESSOR_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 7bd3bd310106..4ce822ed58f5 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -67,7 +67,7 @@ obj-$(CONFIG_KEXEC) += relocate_kernel_$(BITS).o crash.o obj-$(CONFIG_CRASH_DUMP) += crash_dump_$(BITS).o obj-y += kprobes/ obj-$(CONFIG_MODULES) += module.o -obj-$(CONFIG_DOUBLEFAULT) += doublefault_32.o +obj-$(CONFIG_DOUBLEFAULT) += doublefault.o obj-$(CONFIG_KGDB) += kgdb.o obj-$(CONFIG_VM86) += vm86_32.o obj-$(CONFIG_EARLY_PRINTK) += early_printk.o diff --git a/arch/x86/kernel/doublefault.c b/arch/x86/kernel/doublefault.c new file mode 100644 index 000000000000..5d3fe8d36e4a --- /dev/null +++ b/arch/x86/kernel/doublefault.c @@ -0,0 +1,84 @@ +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#ifdef CONFIG_X86_32 + +#define DOUBLEFAULT_STACKSIZE (1024) +static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE]; +#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE) + +#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM) + +static void doublefault_fn(void) +{ + struct desc_ptr gdt_desc = {0, 0}; + unsigned long gdt, tss; + + native_store_gdt(&gdt_desc); + gdt = gdt_desc.address; + + printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); + + if (ptr_ok(gdt)) { + gdt += GDT_ENTRY_TSS << 3; + tss = get_desc_base((struct desc_struct *)gdt); + printk(KERN_EMERG "double fault, tss at %08lx\n", tss); + + if (ptr_ok(tss)) { + struct x86_hw_tss *t = (struct x86_hw_tss *)tss; + + printk(KERN_EMERG "eip = %08lx, esp = %08lx\n", + t->ip, t->sp); + + printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", + t->ax, t->bx, t->cx, t->dx); + printk(KERN_EMERG "esi = %08lx, edi = %08lx\n", + t->si, t->di); + } + } + + for (;;) + cpu_relax(); +} + +struct tss_struct doublefault_tss __cacheline_aligned = { + .x86_tss = { + .sp0 = STACK_START, + .ss0 = __KERNEL_DS, + .ldt = 0, + .io_bitmap_base = INVALID_IO_BITMAP_OFFSET, + + .ip = (unsigned long) doublefault_fn, + /* 0x2 bit is always set */ + .flags = X86_EFLAGS_SF | 0x2, + .sp = STACK_START, + .es = __USER_DS, + .cs = __KERNEL_CS, + .ss = __KERNEL_DS, + .ds = __USER_DS, + .fs = __KERNEL_PERCPU, + + .__cr3 = __pa_nodebug(swapper_pg_dir), + } +}; + +/* dummy for do_double_fault() call */ +void df_debug(struct pt_regs *regs, long error_code) {} + +#else /* !CONFIG_X86_32 */ + +void df_debug(struct pt_regs *regs, long error_code) +{ + pr_emerg("PANIC: double fault, error_code: 0x%lx\n", error_code); + show_regs(regs); + panic("Machine halted."); +} +#endif diff --git a/arch/x86/kernel/doublefault_32.c b/arch/x86/kernel/doublefault_32.c deleted file mode 100644 index 155a13f33ed8..000000000000 --- a/arch/x86/kernel/doublefault_32.c +++ /dev/null @@ -1,69 +0,0 @@ -#include -#include -#include -#include -#include - -#include -#include -#include -#include - -#define DOUBLEFAULT_STACKSIZE (1024) -static unsigned long doublefault_stack[DOUBLEFAULT_STACKSIZE]; -#define STACK_START (unsigned long)(doublefault_stack+DOUBLEFAULT_STACKSIZE) - -#define ptr_ok(x) ((x) > PAGE_OFFSET && (x) < PAGE_OFFSET + MAXMEM) - -static void doublefault_fn(void) -{ - struct desc_ptr gdt_desc = {0, 0}; - unsigned long gdt, tss; - - native_store_gdt(&gdt_desc); - gdt = gdt_desc.address; - - printk(KERN_EMERG "PANIC: double fault, gdt at %08lx [%d bytes]\n", gdt, gdt_desc.size); - - if (ptr_ok(gdt)) { - gdt += GDT_ENTRY_TSS << 3; - tss = get_desc_base((struct desc_struct *)gdt); - printk(KERN_EMERG "double fault, tss at %08lx\n", tss); - - if (ptr_ok(tss)) { - struct x86_hw_tss *t = (struct x86_hw_tss *)tss; - - printk(KERN_EMERG "eip = %08lx, esp = %08lx\n", - t->ip, t->sp); - - printk(KERN_EMERG "eax = %08lx, ebx = %08lx, ecx = %08lx, edx = %08lx\n", - t->ax, t->bx, t->cx, t->dx); - printk(KERN_EMERG "esi = %08lx, edi = %08lx\n", - t->si, t->di); - } - } - - for (;;) - cpu_relax(); -} - -struct tss_struct doublefault_tss __cacheline_aligned = { - .x86_tss = { - .sp0 = STACK_START, - .ss0 = __KERNEL_DS, - .ldt = 0, - .io_bitmap_base = INVALID_IO_BITMAP_OFFSET, - - .ip = (unsigned long) doublefault_fn, - /* 0x2 bit is always set */ - .flags = X86_EFLAGS_SF | 0x2, - .sp = STACK_START, - .es = __USER_DS, - .cs = __KERNEL_CS, - .ss = __KERNEL_DS, - .ds = __USER_DS, - .fs = __KERNEL_PERCPU, - - .__cr3 = __pa_nodebug(swapper_pg_dir), - } -}; diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c index 772e2a846dec..167d481c5fd3 100644 --- a/arch/x86/kernel/traps.c +++ b/arch/x86/kernel/traps.c @@ -254,6 +254,9 @@ dotraplinkage void do_double_fault(struct pt_regs *regs, long error_code) tsk->thread.error_code = error_code; tsk->thread.trap_nr = X86_TRAP_DF; +#ifdef CONFIG_DOUBLEFAULT + df_debug(regs, error_code); +#endif /* * This is always a kernel trap and never fixable (and thus must * never return). -- cgit v1.2.3 From 719038de98bc8479b771c582a1e4a1e86079da22 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Sat, 8 Jun 2013 18:48:15 +0200 Subject: x86/intel/cacheinfo: Shut up last long-standing warning MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit arch/x86/kernel/cpu/intel_cacheinfo.c: In function ‘init_intel_cacheinfo’: arch/x86/kernel/cpu/intel_cacheinfo.c:642:28: warning: ‘this_leaf.size’ may be used uninitialized in this function [-Wmaybe-uninitialized] arch/x86/kernel/cpu/intel_cacheinfo.c:643:29: warning: ‘this_leaf.eax.split.num_threads_sharing’ may be used uninitialized in this function [-Wmaybe-uninitialized] This keeps on happening during randbuilds and the compiler is wrong here: In the case where cpuid4_cache_lookup_regs() returns 0, both this_leaf.size and this_leaf.eax get initialized. In the case where the CPUID leaf doesn't contain valid cache info, we error out which init_intel_cacheinfo() handles correctly without touching the abovementioned fields. So shut up the warning by clearing out the struct which we hand down. While at it, reverse error handling and gain one indentation level. Signed-off-by: Borislav Petkov Link: http://lkml.kernel.org/r/1370710095-20547-1-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/kernel/cpu/intel_cacheinfo.c | 52 +++++++++++++++++------------------ 1 file changed, 25 insertions(+), 27 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_cacheinfo.c b/arch/x86/kernel/cpu/intel_cacheinfo.c index 7c6f7d548c0f..8dc72dda66fe 100644 --- a/arch/x86/kernel/cpu/intel_cacheinfo.c +++ b/arch/x86/kernel/cpu/intel_cacheinfo.c @@ -618,36 +618,34 @@ unsigned int __cpuinit init_intel_cacheinfo(struct cpuinfo_x86 *c) * parameters cpuid leaf to find the cache details */ for (i = 0; i < num_cache_leaves; i++) { - struct _cpuid4_info_regs this_leaf; + struct _cpuid4_info_regs this_leaf = {}; int retval; retval = cpuid4_cache_lookup_regs(i, &this_leaf); - if (retval >= 0) { - switch (this_leaf.eax.split.level) { - case 1: - if (this_leaf.eax.split.type == - CACHE_TYPE_DATA) - new_l1d = this_leaf.size/1024; - else if (this_leaf.eax.split.type == - CACHE_TYPE_INST) - new_l1i = this_leaf.size/1024; - break; - case 2: - new_l2 = this_leaf.size/1024; - num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; - index_msb = get_count_order(num_threads_sharing); - l2_id = c->apicid & ~((1 << index_msb) - 1); - break; - case 3: - new_l3 = this_leaf.size/1024; - num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; - index_msb = get_count_order( - num_threads_sharing); - l3_id = c->apicid & ~((1 << index_msb) - 1); - break; - default: - break; - } + if (retval < 0) + continue; + + switch (this_leaf.eax.split.level) { + case 1: + if (this_leaf.eax.split.type == CACHE_TYPE_DATA) + new_l1d = this_leaf.size/1024; + else if (this_leaf.eax.split.type == CACHE_TYPE_INST) + new_l1i = this_leaf.size/1024; + break; + case 2: + new_l2 = this_leaf.size/1024; + num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; + index_msb = get_count_order(num_threads_sharing); + l2_id = c->apicid & ~((1 << index_msb) - 1); + break; + case 3: + new_l3 = this_leaf.size/1024; + num_threads_sharing = 1 + this_leaf.eax.split.num_threads_sharing; + index_msb = get_count_order(num_threads_sharing); + l3_id = c->apicid & ~((1 << index_msb) - 1); + break; + default: + break; } } } -- cgit v1.2.3