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ARM: probes: avoid adding kprobes to sensitive kernel-entry/exit code

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Avoid adding kprobes to any of the kernel entry/exit or startup
assembly code, or code in the identity-mapped region.  This code does
not conform to the standard C conventions, which means that the
expectations of the kprobes code is not forfilled.

Placing kprobes at some of these locations results in the kernel trying
to return to userspace addresses while retaining the CPU in kernel mode.

Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King 2017-11-24 23:54:22 +00:00
parent 75fea300d7
commit c608906165
11 changed files with 47 additions and 45 deletions
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14
arch/arm/kernel/stacktrace.c
View file

@ -3,6 +3,7 @@
#include <linux/sched/debug.h>
#include <linux/stacktrace.h>
#include <asm/sections.h>
#include <asm/stacktrace.h>
#include <asm/traps.h>
@ -63,7 +64,6 @@ EXPORT_SYMBOL(walk_stackframe);
#ifdef CONFIG_STACKTRACE
struct stack_trace_data {
struct stack_trace *trace;
unsigned long last_pc;
unsigned int no_sched_functions;
unsigned int skip;
};
@ -87,16 +87,7 @@ static int save_trace(struct stackframe *frame, void *d)
if (trace->nr_entries >= trace->max_entries)
return 1;
/*
* in_exception_text() is designed to test if the PC is one of
* the functions which has an exception stack above it, but
* unfortunately what is in frame->pc is the return LR value,
* not the saved PC value. So, we need to track the previous
* frame PC value when doing this.
*/
addr = data->last_pc;
data->last_pc = frame->pc;
if (!in_exception_text(addr))
if (!in_entry_text(frame->pc))
return 0;
regs = (struct pt_regs *)frame->sp;
@ -114,7 +105,6 @@ static noinline void __save_stack_trace(struct task_struct *tsk,
struct stackframe frame;
data.trace = trace;
data.last_pc = ULONG_MAX;
data.skip = trace->skip;
data.no_sched_functions = nosched;