kgdb: fix optional arch functions and probe_kernel_*

Fix two regressions dealing with the kgdb core. 1) kgdb_skipexception and kgdb_post_primary_code are optional functions that are only required on archs that need special exception fixups. 2) The kernel address space scope must be set on any probe_kernel_* function or archs such as ARCH=arm will not allow access to the kernel memory space. As an example, it is required to allow the full kernel address space is when you the kernel debugger to inspect a system call. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>

kgdb: fix optional arch functions and probe_kernel_*
Fix two regressions dealing with the kgdb core. 1) kgdb_skipexception and kgdb_post_primary_code are optional functions that are only required on archs that need special exception fixups. 2) The kernel address space scope must be set on any probe_kernel_* function or archs such as ARCH=arm will not allow access to the kernel memory space. As an example, it is required to allow the full kernel address space is when you the kernel debugger to inspect a system call. Signed-off-by: Jason Wessel <jason.wessel@windriver.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Jason Wessel · Ingo Molnar
1 parent 64e9ee3095
Showing 2 changed files with 17 additions and 0 deletions Side-by-side Diff
kernel/kgdb.c
mm/maccess.c
@@ -200,6 +200,17 @@
 	return 0;
 }
  
+int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
+{
+	return 0;
+}
+
+void __weak
+kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
+{
+	return;
+}
+
 /**
  *	kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
  *	@regs: Current &struct pt_regs.
@@ -17,11 +17,14 @@
 long probe_kernel_read(void *dst, void *src, size_t size)
 {
 	long ret;
+	mm_segment_t old_fs = get_fs();
  
+	set_fs(KERNEL_DS);
 	pagefault_disable();
 	ret = __copy_from_user_inatomic(dst,
 			(__force const void __user *)src, size);
 	pagefault_enable();
+	set_fs(old_fs);
  
 	return ret ? -EFAULT : 0;
 }
  
  
@@ -39,10 +42,13 @@
 long probe_kernel_write(void *dst, void *src, size_t size)
 {
 	long ret;
+	mm_segment_t old_fs = get_fs();
  
+	set_fs(KERNEL_DS);
 	pagefault_disable();
 	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
 	pagefault_enable();
+	set_fs(old_fs);
  
 	return ret ? -EFAULT : 0;
 }
...	...	@@ -200,6 +200,17 @@
200	200	return 0;
201	201	}
202	202
	203	+int __weak kgdb_skipexception(int exception, struct pt_regs *regs)
	204	+{
	205	+ return 0;
	206	+}
	207	+
	208	+void __weak
	209	+kgdb_post_primary_code(struct pt_regs *regs, int e_vector, int err_code)
	210	+{
	211	+ return;
	212	+}
	213	+
203	214	/**
204	215	* kgdb_disable_hw_debug - Disable hardware debugging while we in kgdb.
205	216	* @regs: Current &struct pt_regs.
...	...	@@ -17,11 +17,14 @@
17	17	long probe_kernel_read(void dst, void src, size_t size)
18	18	{
19	19	long ret;
	20	+ mm_segment_t old_fs = get_fs();
20	21
	22	+ set_fs(KERNEL_DS);
21	23	pagefault_disable();
22	24	ret = __copy_from_user_inatomic(dst,
23	25	(__force const void __user *)src, size);
24	26	pagefault_enable();
	27	+ set_fs(old_fs);
25	28
26	29	return ret ? -EFAULT : 0;
27	30	}
28	31
29	32
...	...	@@ -39,10 +42,13 @@
39	42	long probe_kernel_write(void dst, void src, size_t size)
40	43	{
41	44	long ret;
	45	+ mm_segment_t old_fs = get_fs();
42	46
	47	+ set_fs(KERNEL_DS);
43	48	pagefault_disable();
44	49	ret = __copy_to_user_inatomic((__force void __user *)dst, src, size);
45	50	pagefault_enable();
	51	+ set_fs(old_fs);
46	52
47	53	return ret ? -EFAULT : 0;
48	54	}