[PATCH] i386: get rid of the use of KPROBE_ENTRY / KPROBE_END

entry_32.S is now the only user of KPROBE_ENTRY / KPROBE_END,
treewide. This patch reorders entry_64.S and explicitly generates
a separate section for functions that need the protection. The
generated code before and after the patch is equal.

The KPROBE_ENTRY and KPROBE_END macro's are removed too.

Signed-off-by: Alexander van Heukelum <heukelum@xxxxxxxxxxx>
---
arch/x86/kernel/entry_32.S | 438 ++++++++++++++++++++++---------------------
include/linux/linkage.h | 8 -
2 files changed, 224 insertions(+), 222 deletions(-)

On Mon, Nov 24, 2008 at 01:33:49PM +0000, Jan Beulich wrote:
I like things being done this way (including the goal of doing away with
KPROBE_{ENTRY,END} altogether). Thanks a lot! Jan

Thanks for the comment. Here is the i386-side of the patch, including
the removal of the KPROBE_ENTRY and KPROBE_END macro's.

Greetings,
Alexander

diff --git a/arch/x86/kernel/entry_32.S b/arch/x86/kernel/entry_32.S
index bd02ec7..6e96028 100644
--- a/arch/x86/kernel/entry_32.S
+++ b/arch/x86/kernel/entry_32.S
@@ -688,65 +688,6 @@ ENDPROC(name)
/* The include is where all of the SMP etc. interrupts come from */
#include "entry_arch.h"

-KPROBE_ENTRY(page_fault)
- RING0_EC_FRAME
- pushl $do_page_fault
- CFI_ADJUST_CFA_OFFSET 4
- ALIGN
-error_code:
- /* the function address is in %fs's slot on the stack */
- pushl %es
- CFI_ADJUST_CFA_OFFSET 4
- /*CFI_REL_OFFSET es, 0*/
- pushl %ds
- CFI_ADJUST_CFA_OFFSET 4
- /*CFI_REL_OFFSET ds, 0*/
- pushl %eax
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET eax, 0
- pushl %ebp
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET ebp, 0
- pushl %edi
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET edi, 0
- pushl %esi
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET esi, 0
- pushl %edx
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET edx, 0
- pushl %ecx
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET ecx, 0
- pushl %ebx
- CFI_ADJUST_CFA_OFFSET 4
- CFI_REL_OFFSET ebx, 0
- cld
- pushl %fs
- CFI_ADJUST_CFA_OFFSET 4
- /*CFI_REL_OFFSET fs, 0*/
- movl $(__KERNEL_PERCPU), %ecx
- movl %ecx, %fs
- UNWIND_ESPFIX_STACK
- popl %ecx
- CFI_ADJUST_CFA_OFFSET -4
- /*CFI_REGISTER es, ecx*/
- movl PT_FS(%esp), %edi # get the function address
- movl PT_ORIG_EAX(%esp), %edx # get the error code
- movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
- mov %ecx, PT_FS(%esp)
- /*CFI_REL_OFFSET fs, ES*/
- movl $(__USER_DS), %ecx
- movl %ecx, %ds
- movl %ecx, %es
- TRACE_IRQS_OFF
- movl %esp,%eax # pt_regs pointer
- call *%edi
- jmp ret_from_exception
- CFI_ENDPROC
-KPROBE_END(page_fault)
-
ENTRY(coprocessor_error)
RING0_INT_FRAME
pushl $0
@@ -777,140 +718,6 @@ ENTRY(device_not_available)
CFI_ENDPROC
END(device_not_available)

-/*
- * Debug traps and NMI can happen at the one SYSENTER instruction
- * that sets up the real kernel stack. Check here, since we can't
- * allow the wrong stack to be used.
- *
- * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
- * already pushed 3 words if it hits on the sysenter instruction:
- * eflags, cs and eip.
- *
- * We just load the right stack, and push the three (known) values
- * by hand onto the new stack - while updating the return eip past
- * the instruction that would have done it for sysenter.
- */
-#define FIX_STACK(offset, ok, label) \
- cmpw $__KERNEL_CS,4(%esp); \
- jne ok; \
-label: \
- movl TSS_sysenter_sp0+offset(%esp),%esp; \
- CFI_DEF_CFA esp, 0; \
- CFI_UNDEFINED eip; \
- pushfl; \
- CFI_ADJUST_CFA_OFFSET 4; \
- pushl $__KERNEL_CS; \
- CFI_ADJUST_CFA_OFFSET 4; \
- pushl $sysenter_past_esp; \
- CFI_ADJUST_CFA_OFFSET 4; \
- CFI_REL_OFFSET eip, 0
-
-KPROBE_ENTRY(debug)
- RING0_INT_FRAME
- cmpl $ia32_sysenter_target,(%esp)
- jne debug_stack_correct
- FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
-debug_stack_correct:
- pushl $-1 # mark this as an int
- CFI_ADJUST_CFA_OFFSET 4
- SAVE_ALL
- TRACE_IRQS_OFF
- xorl %edx,%edx # error code 0
- movl %esp,%eax # pt_regs pointer
- call do_debug
- jmp ret_from_exception
- CFI_ENDPROC
-KPROBE_END(debug)
-
-/*
- * NMI is doubly nasty. It can happen _while_ we're handling
- * a debug fault, and the debug fault hasn't yet been able to
- * clear up the stack. So we first check whether we got an
- * NMI on the sysenter entry path, but after that we need to
- * check whether we got an NMI on the debug path where the debug
- * fault happened on the sysenter path.
- */
-KPROBE_ENTRY(nmi)
- RING0_INT_FRAME
- pushl %eax
- CFI_ADJUST_CFA_OFFSET 4
- movl %ss, %eax
- cmpw $__ESPFIX_SS, %ax
- popl %eax
- CFI_ADJUST_CFA_OFFSET -4
- je nmi_espfix_stack
- cmpl $ia32_sysenter_target,(%esp)
- je nmi_stack_fixup
- pushl %eax
- CFI_ADJUST_CFA_OFFSET 4
- movl %esp,%eax
- /* Do not access memory above the end of our stack page,
- * it might not exist.
- */
- andl $(THREAD_SIZE-1),%eax
- cmpl $(THREAD_SIZE-20),%eax
- popl %eax
- CFI_ADJUST_CFA_OFFSET -4
- jae nmi_stack_correct
- cmpl $ia32_sysenter_target,12(%esp)
- je nmi_debug_stack_check
-nmi_stack_correct:
- /* We have a RING0_INT_FRAME here */
- pushl %eax
- CFI_ADJUST_CFA_OFFSET 4
- SAVE_ALL
- TRACE_IRQS_OFF
- xorl %edx,%edx # zero error code
- movl %esp,%eax # pt_regs pointer
- call do_nmi
- jmp restore_nocheck_notrace
- CFI_ENDPROC
-
-nmi_stack_fixup:
- RING0_INT_FRAME
- FIX_STACK(12,nmi_stack_correct, 1)
- jmp nmi_stack_correct
-
-nmi_debug_stack_check:
- /* We have a RING0_INT_FRAME here */
- cmpw $__KERNEL_CS,16(%esp)
- jne nmi_stack_correct
- cmpl $debug,(%esp)
- jb nmi_stack_correct
- cmpl $debug_esp_fix_insn,(%esp)
- ja nmi_stack_correct
- FIX_STACK(24,nmi_stack_correct, 1)
- jmp nmi_stack_correct
-
-nmi_espfix_stack:
- /* We have a RING0_INT_FRAME here.
- *
- * create the pointer to lss back
- */
- pushl %ss
- CFI_ADJUST_CFA_OFFSET 4
- pushl %esp
- CFI_ADJUST_CFA_OFFSET 4
- addw $4, (%esp)
- /* copy the iret frame of 12 bytes */
- .rept 3
- pushl 16(%esp)
- CFI_ADJUST_CFA_OFFSET 4
- .endr
- pushl %eax
- CFI_ADJUST_CFA_OFFSET 4
- SAVE_ALL
- TRACE_IRQS_OFF
- FIXUP_ESPFIX_STACK # %eax == %esp
- xorl %edx,%edx # zero error code
- call do_nmi
- RESTORE_REGS
- lss 12+4(%esp), %esp # back to espfix stack
- CFI_ADJUST_CFA_OFFSET -24
- jmp irq_return
- CFI_ENDPROC
-KPROBE_END(nmi)
-
#ifdef CONFIG_PARAVIRT
ENTRY(native_iret)
iret
@@ -926,19 +733,6 @@ ENTRY(native_irq_enable_sysexit)
END(native_irq_enable_sysexit)
#endif

-KPROBE_ENTRY(int3)
- RING0_INT_FRAME
- pushl $-1 # mark this as an int
- CFI_ADJUST_CFA_OFFSET 4
- SAVE_ALL
- TRACE_IRQS_OFF
- xorl %edx,%edx # zero error code
- movl %esp,%eax # pt_regs pointer
- call do_int3
- jmp ret_from_exception
- CFI_ENDPROC
-KPROBE_END(int3)
-
ENTRY(overflow)
RING0_INT_FRAME
pushl $0
@@ -1003,14 +797,6 @@ ENTRY(stack_segment)
CFI_ENDPROC
END(stack_segment)

-KPROBE_ENTRY(general_protection)
- RING0_EC_FRAME
- pushl $do_general_protection
- CFI_ADJUST_CFA_OFFSET 4
- jmp error_code
- CFI_ENDPROC
-KPROBE_END(general_protection)
-
ENTRY(alignment_check)
RING0_EC_FRAME
pushl $do_alignment_check
@@ -1220,3 +1006,227 @@ END(mcount)
#include "syscall_table_32.S"

syscall_table_size=(.-sys_call_table)
+
+/*
+ * Some functions should be protected against kprobes
+ */
+ .pushsection .kprobes.text, "ax"
+
+ENTRY(page_fault)
+ RING0_EC_FRAME
+ pushl $do_page_fault
+ CFI_ADJUST_CFA_OFFSET 4
+ ALIGN
+error_code:
+ /* the function address is in %fs's slot on the stack */
+ pushl %es
+ CFI_ADJUST_CFA_OFFSET 4
+ /*CFI_REL_OFFSET es, 0*/
+ pushl %ds
+ CFI_ADJUST_CFA_OFFSET 4
+ /*CFI_REL_OFFSET ds, 0*/
+ pushl %eax
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET eax, 0
+ pushl %ebp
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ebp, 0
+ pushl %edi
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edi, 0
+ pushl %esi
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET esi, 0
+ pushl %edx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET edx, 0
+ pushl %ecx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ecx, 0
+ pushl %ebx
+ CFI_ADJUST_CFA_OFFSET 4
+ CFI_REL_OFFSET ebx, 0
+ cld
+ pushl %fs
+ CFI_ADJUST_CFA_OFFSET 4
+ /*CFI_REL_OFFSET fs, 0*/
+ movl $(__KERNEL_PERCPU), %ecx
+ movl %ecx, %fs
+ UNWIND_ESPFIX_STACK
+ popl %ecx
+ CFI_ADJUST_CFA_OFFSET -4
+ /*CFI_REGISTER es, ecx*/
+ movl PT_FS(%esp), %edi # get the function address
+ movl PT_ORIG_EAX(%esp), %edx # get the error code
+ movl $-1, PT_ORIG_EAX(%esp) # no syscall to restart
+ mov %ecx, PT_FS(%esp)
+ /*CFI_REL_OFFSET fs, ES*/
+ movl $(__USER_DS), %ecx
+ movl %ecx, %ds
+ movl %ecx, %es
+ TRACE_IRQS_OFF
+ movl %esp,%eax # pt_regs pointer
+ call *%edi
+ jmp ret_from_exception
+ CFI_ENDPROC
+END(page_fault)
+
+/*
+ * Debug traps and NMI can happen at the one SYSENTER instruction
+ * that sets up the real kernel stack. Check here, since we can't
+ * allow the wrong stack to be used.
+ *
+ * "TSS_sysenter_sp0+12" is because the NMI/debug handler will have
+ * already pushed 3 words if it hits on the sysenter instruction:
+ * eflags, cs and eip.
+ *
+ * We just load the right stack, and push the three (known) values
+ * by hand onto the new stack - while updating the return eip past
+ * the instruction that would have done it for sysenter.
+ */
+#define FIX_STACK(offset, ok, label) \
+ cmpw $__KERNEL_CS,4(%esp); \
+ jne ok; \
+label: \
+ movl TSS_sysenter_sp0+offset(%esp),%esp; \
+ CFI_DEF_CFA esp, 0; \
+ CFI_UNDEFINED eip; \
+ pushfl; \
+ CFI_ADJUST_CFA_OFFSET 4; \
+ pushl $__KERNEL_CS; \
+ CFI_ADJUST_CFA_OFFSET 4; \
+ pushl $sysenter_past_esp; \
+ CFI_ADJUST_CFA_OFFSET 4; \
+ CFI_REL_OFFSET eip, 0
+
+ENTRY(debug)
+ RING0_INT_FRAME
+ cmpl $ia32_sysenter_target,(%esp)
+ jne debug_stack_correct
+ FIX_STACK(12, debug_stack_correct, debug_esp_fix_insn)
+debug_stack_correct:
+ pushl $-1 # mark this as an int
+ CFI_ADJUST_CFA_OFFSET 4
+ SAVE_ALL
+ TRACE_IRQS_OFF
+ xorl %edx,%edx # error code 0
+ movl %esp,%eax # pt_regs pointer
+ call do_debug
+ jmp ret_from_exception
+ CFI_ENDPROC
+END(debug)
+
+/*
+ * NMI is doubly nasty. It can happen _while_ we're handling
+ * a debug fault, and the debug fault hasn't yet been able to
+ * clear up the stack. So we first check whether we got an
+ * NMI on the sysenter entry path, but after that we need to
+ * check whether we got an NMI on the debug path where the debug
+ * fault happened on the sysenter path.
+ */
+ENTRY(nmi)
+ RING0_INT_FRAME
+ pushl %eax
+ CFI_ADJUST_CFA_OFFSET 4
+ movl %ss, %eax
+ cmpw $__ESPFIX_SS, %ax
+ popl %eax
+ CFI_ADJUST_CFA_OFFSET -4
+ je nmi_espfix_stack
+ cmpl $ia32_sysenter_target,(%esp)
+ je nmi_stack_fixup
+ pushl %eax
+ CFI_ADJUST_CFA_OFFSET 4
+ movl %esp,%eax
+ /* Do not access memory above the end of our stack page,
+ * it might not exist.
+ */
+ andl $(THREAD_SIZE-1),%eax
+ cmpl $(THREAD_SIZE-20),%eax
+ popl %eax
+ CFI_ADJUST_CFA_OFFSET -4
+ jae nmi_stack_correct
+ cmpl $ia32_sysenter_target,12(%esp)
+ je nmi_debug_stack_check
+nmi_stack_correct:
+ /* We have a RING0_INT_FRAME here */
+ pushl %eax
+ CFI_ADJUST_CFA_OFFSET 4
+ SAVE_ALL
+ TRACE_IRQS_OFF
+ xorl %edx,%edx # zero error code
+ movl %esp,%eax # pt_regs pointer
+ call do_nmi
+ jmp restore_nocheck_notrace
+ CFI_ENDPROC
+
+nmi_stack_fixup:
+ RING0_INT_FRAME
+ FIX_STACK(12,nmi_stack_correct, 1)
+ jmp nmi_stack_correct
+
+nmi_debug_stack_check:
+ /* We have a RING0_INT_FRAME here */
+ cmpw $__KERNEL_CS,16(%esp)
+ jne nmi_stack_correct
+ cmpl $debug,(%esp)
+ jb nmi_stack_correct
+ cmpl $debug_esp_fix_insn,(%esp)
+ ja nmi_stack_correct
+ FIX_STACK(24,nmi_stack_correct, 1)
+ jmp nmi_stack_correct
+
+nmi_espfix_stack:
+ /* We have a RING0_INT_FRAME here.
+ *
+ * create the pointer to lss back
+ */
+ pushl %ss
+ CFI_ADJUST_CFA_OFFSET 4
+ pushl %esp
+ CFI_ADJUST_CFA_OFFSET 4
+ addw $4, (%esp)
+ /* copy the iret frame of 12 bytes */
+ .rept 3
+ pushl 16(%esp)
+ CFI_ADJUST_CFA_OFFSET 4
+ .endr
+ pushl %eax
+ CFI_ADJUST_CFA_OFFSET 4
+ SAVE_ALL
+ TRACE_IRQS_OFF
+ FIXUP_ESPFIX_STACK # %eax == %esp
+ xorl %edx,%edx # zero error code
+ call do_nmi
+ RESTORE_REGS
+ lss 12+4(%esp), %esp # back to espfix stack
+ CFI_ADJUST_CFA_OFFSET -24
+ jmp irq_return
+ CFI_ENDPROC
+END(nmi)
+
+ENTRY(int3)
+ RING0_INT_FRAME
+ pushl $-1 # mark this as an int
+ CFI_ADJUST_CFA_OFFSET 4
+ SAVE_ALL
+ TRACE_IRQS_OFF
+ xorl %edx,%edx # zero error code
+ movl %esp,%eax # pt_regs pointer
+ call do_int3
+ jmp ret_from_exception
+ CFI_ENDPROC
+END(int3)
+
+ENTRY(general_protection)
+ RING0_EC_FRAME
+ pushl $do_general_protection
+ CFI_ADJUST_CFA_OFFSET 4
+ jmp error_code
+ CFI_ENDPROC
+END(general_protection)
+
+/*
+ * End of kprobes section
+ */
+ .popsection
diff --git a/include/linux/linkage.h b/include/linux/linkage.h
index 9fd1f85..fee9e59 100644
--- a/include/linux/linkage.h
+++ b/include/linux/linkage.h
@@ -64,14 +64,6 @@
name:
#endif

-#define KPROBE_ENTRY(name) \
- .pushsection .kprobes.text, "ax"; \
- ENTRY(name)
-
-#define KPROBE_END(name) \
- END(name); \
- .popsection
-
#ifndef END
#define END(name) \
.size name, .-name
--
1.5.4.3

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