* [RFC][PATCH] x86 transition to 4k stacks (2/3)
@ 2002-10-15 6:00 Dave Hansen
0 siblings, 0 replies; only message in thread
From: Dave Hansen @ 2002-10-15 6:00 UTC (permalink / raw)
To: linux-kernel
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* stack checking (2/3)
- 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.
--
Dave Hansen
haveblue@us.ibm.com
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# 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 1.851 -> 1.852
# arch/i386/kernel/process.c 1.32 -> 1.33
# arch/i386/Config.help 1.21 -> 1.22
# Makefile 1.320 -> 1.321
# arch/i386/kernel/entry.S 1.38 -> 1.39
# arch/i386/config.in 1.56 -> 1.57
# arch/i386/Makefile 1.21 -> 1.22
# arch/i386/boot/compressed/misc.c 1.9 -> 1.10
# arch/i386/kernel/init_task.c 1.6 -> 1.7
# arch/i386/kernel/i386_ksyms.c 1.34 -> 1.35
#
# The following is the BitKeeper ChangeSet Log
# --------------------------------------------
# 02/10/14 haveblue@elm3b96.(none) 1.852
# stack_usage_check-2.5.42+bk-1.patch
# --------------------------------------------
#
diff -Nru a/Makefile b/Makefile
--- a/Makefile Mon Oct 14 19:54:47 2002
+++ b/Makefile Mon Oct 14 19:54:47 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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/Config.help Mon Oct 14 19:54:47 2002
@@ -1044,6 +1044,10 @@
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.
+
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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/Makefile Mon Oct 14 19:54:47 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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/boot/compressed/misc.c Mon Oct 14 19:54:47 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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/config.in Mon Oct 14 19:54:47 2002
@@ -458,6 +458,11 @@
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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/kernel/entry.S Mon Oct 14 19:54:47 2002
@@ -481,6 +481,67 @@
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 $0x200,%eax /* 512 byte danger zone */
+ jle 1f /* this wil panic */
+ cmpl $0x1000,%eax /* 4k stack would have overflowed */
+ jle 2f /* this will just warn */
+3:
+ popl %eax
+ ret
+2:
+ call stack_overflow_warn
+ jc 3b
+1:
+ lock; btsl $0,stack_overflowed /* Prevent reentry via printk */
+ jc 3b
+
+ # 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
+
+ # never neverland
+ call stack_overflow_panic
+
+ addl $8,%esp
+
+ popf
+ popl %eax
+ 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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/kernel/i386_ksyms.c Mon Oct 14 19:54:47 2002
@@ -182,3 +182,8 @@
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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/kernel/init_task.c Mon Oct 14 19:54:47 2002
@@ -13,6 +13,11 @@
static struct signal_struct init_signals = INIT_SIGNALS(init_signals);
struct mm_struct init_mm = INIT_MM(init_mm);
+#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 Mon Oct 14 19:54:47 2002
+++ b/arch/i386/kernel/process.c Mon Oct 14 19:54:47 2002
@@ -156,7 +156,21 @@
__setup("idle=", idle_setup);
-void show_regs(struct pt_regs * regs)
+void stack_overflow_warn(void *esp, unsigned long eip)
+{
+ print_symbol("excessive stack use from %s\n", eip);
+ printk("esp: %p\n", esp);
+ show_trace(esp);
+}
+
+void stack_overflow_panic(void *esp, void *eip)
+{
+ printk("stack overflow from %p. esp: %p\n", eip, esp);
+ show_trace(esp);
+ panic("stack overflow\n");
+}
+
+asmlinkage void show_regs(struct pt_regs * regs)
{
unsigned long cr0 = 0L, cr2 = 0L, cr3 = 0L, cr4 = 0L;
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2002-10-15 6:00 [RFC][PATCH] x86 transition to 4k stacks (2/3) Dave Hansen
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