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authorJason Wessel <jason.wessel@windriver.com>2012-03-23 09:35:05 -0500
committerJason Wessel <jason.wessel@windriver.com>2012-03-29 17:41:25 -0500
commit3751d3e85cf693e10e2c47c03c8caa65e171099b (patch)
tree65d123dac17103f6862831bcb4271b263805fd9f /drivers/misc
parent98b54aa1a2241b59372468bd1e9c2d207bdba54b (diff)
x86,kgdb: Fix DEBUG_RODATA limitation using text_poke()
There has long been a limitation using software breakpoints with a kernel compiled with CONFIG_DEBUG_RODATA going back to 2.6.26. For this particular patch, it will apply cleanly and has been tested all the way back to 2.6.36. The kprobes code uses the text_poke() function which accommodates writing a breakpoint into a read-only page. The x86 kgdb code can solve the problem similarly by overriding the default breakpoint set/remove routines and using text_poke() directly. The x86 kgdb code will first attempt to use the traditional probe_kernel_write(), and next try using a the text_poke() function. The break point install method is tracked such that the correct break point removal routine will get called later on. Cc: x86@kernel.org Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: stable@vger.kernel.org # >= 2.6.36 Inspried-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/kgdbts.c17
1 files changed, 0 insertions, 17 deletions
diff --git a/drivers/misc/kgdbts.c b/drivers/misc/kgdbts.c
index d087456ba08..3aa9a969b37 100644
--- a/drivers/misc/kgdbts.c
+++ b/drivers/misc/kgdbts.c
@@ -968,22 +968,6 @@ static void run_singlestep_break_test(void)
kgdbts_break_test();
}
-static void test_debug_rodata(void)
-{
-#ifdef CONFIG_DEBUG_RODATA
- /* Until there is an api to write to read-only text segments, use
- * HW breakpoints for the remainder of any tests, else print a
- * failure message if hw breakpoints do not work.
- */
- if (!(arch_kgdb_ops.flags & KGDB_HW_BREAKPOINT && hwbreaks_ok)) {
- eprintk("kgdbts: HW breakpoints BROKEN, ending tests\n");
- return;
- }
- force_hwbrks = 1;
- v1printk("kgdbts:Using HW breakpoints for SW breakpoint tests\n");
-#endif /* CONFIG_DEBUG_RODATA */
-}
-
static void kgdbts_run_tests(void)
{
char *ptr;
@@ -1016,7 +1000,6 @@ static void kgdbts_run_tests(void)
v1printk("kgdbts:RUN access write breakpoint test\n");
run_hw_break_test(0);
}
- test_debug_rodata();
/* required internal KGDB tests */
v1printk("kgdbts:RUN plant and detach test\n");