* stack checking (3/3)
- use gcc's profiling features to check for stack overflows upon
entry to functions.
- Warn if the task goes over 4k.
- Panic if the stack gets within 512 bytes of overflowing.
- use kksymoops information, if available
This won't apply cleanly without the irqstack patch, but the conflict
is easy to resolve. It requires the thread_info cleanup.
-- Dave Hansen haveblue@us.ibm.com--------------000403010909030606060800 Content-Type: text/plain; name="C-stack_usage_check-2.5.43+bk-1.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="C-stack_usage_check-2.5.43+bk-1.patch"
# This is a BitKeeper generated patch for the following project: # Project Name: Linux kernel tree # This patch format is intended for GNU patch command version 2.5 or higher. # This patch includes the following deltas: # ChangeSet 1.858.1.2 -> 1.863 # arch/i386/kernel/process.c 1.32.1.1 -> 1.36 # arch/i386/Config.help 1.21.1.2 -> 1.24 # Makefile 1.320.1.1 -> 1.322 # include/asm-i386/thread_info.h 1.10 -> 1.11 # arch/i386/kernel/entry.S 1.38.1.2 -> 1.45 # arch/i386/config.in 1.56.1.4 -> 1.59 # arch/i386/Makefile 1.21.1.1 -> 1.23 # arch/i386/boot/compressed/misc.c 1.9 -> 1.10 # arch/i386/kernel/init_task.c 1.6.1.1 -> 1.8 # arch/i386/kernel/i386_ksyms.c 1.34.1.2 -> 1.36 # # The following is the BitKeeper ChangeSet Log # -------------------------------------------- # 02/10/16 haveblue@elm3b96.(none) 1.861 # change warning semantics # -------------------------------------------- # 02/10/16 haveblue@elm3b96.(none) 1.862 # entry.S: # don't need stack_warn_lock anymore # -------------------------------------------- # 02/10/16 haveblue@elm3b96.(none) 1.863 # merge # -------------------------------------------- # diff -Nru a/Makefile b/Makefile --- a/Makefile Wed Oct 16 14:14:00 2002 +++ b/Makefile Wed Oct 16 14:14:00 2002 @@ -156,7 +156,8 @@ CPPFLAGS := -D__KERNEL__ -Iinclude CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes -Wno-trigraphs -O2 \ - -fomit-frame-pointer -fno-strict-aliasing -fno-common + -fno-strict-aliasing -fno-common + AFLAGS := -D__ASSEMBLY__ $(CPPFLAGS) export VERSION PATCHLEVEL SUBLEVEL EXTRAVERSION KERNELRELEASE ARCH \ @@ -255,6 +256,10 @@ ifdef CONFIG_MODULES export EXPORT_FLAGS := -DEXPORT_SYMTAB +endif + +ifneq ($(CONFIG_FRAME_POINTER),y) +CFLAGS += -fomit-frame-pointer endif # diff -Nru a/arch/i386/Config.help b/arch/i386/Config.help --- a/arch/i386/Config.help Wed Oct 16 14:14:00 2002 +++ b/arch/i386/Config.help Wed Oct 16 14:14:00 2002 @@ -1050,6 +1050,20 @@ symbolic stack backtraces. This increases the size of the kernel somewhat, as all symbols have to be loaded into the kernel image. +CONFIG_X86_STACK_CHECK + Say Y here to have the kernel attempt to detect when the per-task + kernel stack overflows. + + Some older versions of gcc don't handle the -p option correctly. + Kernprof is affected by the same problem, which is described here: + http://oss.sgi.com/projects/kernprof/faq.html#Q9 + + Basically, if you get oopses in __free_pages_ok during boot when + you have this turned on, you need to fix gcc. The Redhat 2.96 + version and gcc-3.x seem to work. + + If not debugging a stack overflow problem, say N + CONFIG_DEBUG_OBSOLETE Say Y here if you want to reduce the chances of the tree compiling, and are prepared to dig into driver internals to fix compile errors. diff -Nru a/arch/i386/Makefile b/arch/i386/Makefile --- a/arch/i386/Makefile Wed Oct 16 14:14:00 2002 +++ b/arch/i386/Makefile Wed Oct 16 14:14:00 2002 @@ -49,6 +49,10 @@ MACHINE := mach-generic endif +ifdef CONFIG_X86_STACK_CHECK +CFLAGS += -p +endif + HEAD := arch/i386/kernel/head.o arch/i386/kernel/init_task.o libs-y += arch/i386/lib/ diff -Nru a/arch/i386/boot/compressed/misc.c b/arch/i386/boot/compressed/misc.c --- a/arch/i386/boot/compressed/misc.c Wed Oct 16 14:14:00 2002 +++ b/arch/i386/boot/compressed/misc.c Wed Oct 16 14:14:00 2002 @@ -377,3 +377,7 @@ if (high_loaded) close_output_buffer_if_we_run_high(mv); return high_loaded; } + +/* We don't actually check for stack overflows this early. */ +__asm__(".globl mcount ; mcount: ret\n"); + diff -Nru a/arch/i386/config.in b/arch/i386/config.in --- a/arch/i386/config.in Wed Oct 16 14:14:00 2002 +++ b/arch/i386/config.in Wed Oct 16 14:14:00 2002 @@ -467,6 +467,11 @@ bool ' Highmem debugging' CONFIG_DEBUG_HIGHMEM fi bool ' Load all symbols for debugging/kksymoops' CONFIG_KALLSYMS + bool ' Check for stack overflows' CONFIG_X86_STACK_CHECK + if [ "$CONFIG_X86_STACK_CHECK" = "y" ]; then + define_bool CONFIG_FRAME_POINTER y + fi + fi if [ "$CONFIG_X86_LOCAL_APIC" = "y" ]; then diff -Nru a/arch/i386/kernel/entry.S b/arch/i386/kernel/entry.S --- a/arch/i386/kernel/entry.S Wed Oct 16 14:14:00 2002 +++ b/arch/i386/kernel/entry.S Wed Oct 16 14:14:00 2002 @@ -519,6 +519,61 @@ pushl $do_spurious_interrupt_bug jmp error_code + +#ifdef CONFIG_X86_STACK_CHECK +.data + .globl stack_overflowed +stack_overflowed: + .long 0 +.text + +ENTRY(mcount) + push %eax + movl $(THREAD_SIZE - 1),%eax + andl %esp,%eax + cmpl $STACK_WARN,%eax /* more than half the stack is used*/ + jle 1f +2: + popl %eax + ret +1: + lock; btsl $0,stack_overflowed + jc 2b + + # switch to overflow stack + movl %esp,%eax + movl $(stack_overflow_stack + THREAD_SIZE - 4),%esp + + pushf + cli + pushl %eax + + # push eip then esp of error for stack_overflow_panic + pushl 4(%eax) + pushl %eax + + # update the task pointer and cpu in the overflow stack's thread_info. + GET_THREAD_INFO_WITH_ESP(%eax) + movl TI_TASK(%eax),%ebx + movl %ebx,stack_overflow_stack+TI_TASK + movl TI_CPU(%eax),%ebx + movl %ebx,stack_overflow_stack+TI_CPU + + call stack_overflow + + # pop off call arguments + addl $8,%esp + + popl %eax + popf + movl %eax,%esp + popl %eax + movl $0,stack_overflowed + ret + +#warning stack check enabled +#endif + .data ENTRY(sys_call_table) .long sys_ni_syscall /* 0 - old "setup()" system call*/ diff -Nru a/arch/i386/kernel/i386_ksyms.c b/arch/i386/kernel/i386_ksyms.c --- a/arch/i386/kernel/i386_ksyms.c Wed Oct 16 14:14:00 2002 +++ b/arch/i386/kernel/i386_ksyms.c Wed Oct 16 14:14:00 2002 @@ -192,3 +192,8 @@ EXPORT_SYMBOL(is_sony_vaio_laptop); EXPORT_SYMBOL(__PAGE_KERNEL); + +#ifdef CONFIG_X86_STACK_CHECK +extern void mcount(void); +EXPORT_SYMBOL(mcount); +#endif diff -Nru a/arch/i386/kernel/init_task.c b/arch/i386/kernel/init_task.c --- a/arch/i386/kernel/init_task.c Wed Oct 16 14:14:00 2002 +++ b/arch/i386/kernel/init_task.c Wed Oct 16 14:14:00 2002 @@ -16,6 +16,10 @@ union thread_union init_irq_union __attribute__((__section__(".data.init_task"))); +#ifdef CONFIG_X86_STACK_CHECK +union thread_union stack_overflow_stack + __attribute__((__section__(".data.init_task"))); +#endif /* * Initial thread structure. diff -Nru a/arch/i386/kernel/process.c b/arch/i386/kernel/process.c --- a/arch/i386/kernel/process.c Wed Oct 16 14:14:00 2002 +++ b/arch/i386/kernel/process.c Wed Oct 16 14:14:00 2002 @@ -156,7 +156,25 @@ __setup("idle=", idle_setup); -void show_regs(struct pt_regs * regs) +void stack_overflow(unsigned long esp, unsigned long eip) +{ + int panicing = ((esp&(THREAD_SIZE-1)) <= STACK_PANIC); + + printk( "esp: 0x%x masked: 0x%x STACK_PANIC:0x%x %d %d\n", + esp, (esp&(THREAD_SIZE-1)), STACK_PANIC, (((esp&(THREAD_SIZE-1)) <= STACK_PANIC)), panicing ); + + if (panicing) + print_symbol("stack overflow from %s\n", eip); + else + print_symbol("excessive stack use from %s\n", eip); + printk("esp: %p\n", (void*)esp); + show_trace((void*)esp); + + if (panicing) + panic("stack overflow\n"); +} + +asmlinkage void show_regs(struct pt_regs * regs) { unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L; diff -Nru a/include/asm-i386/thread_info.h b/include/asm-i386/thread_info.h --- a/include/asm-i386/thread_info.h Wed Oct 16 14:14:00 2002 +++ b/include/asm-i386/thread_info.h Wed Oct 16 14:14:00 2002 @@ -60,6 +60,8 @@ */ #define THREAD_ORDER 1 #define INIT_THREAD_SIZE THREAD_SIZE +#define STACK_PANIC 0x200ul +#define STACK_WARN ((THREAD_SIZE)>>1) #ifndef __ASSEMBLY__ #define INIT_THREAD_INFO(tsk) \
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