Re: [RFC V2] mm: Generalize notify_page_fault()

On 06/04/2019 12:24 PM, Peter Zijlstra wrote:

On Tue, Jun 04, 2019 at 12:04:06PM +0530, Anshuman Khandual wrote:

quoted

diff --git a/mm/memory.c b/mm/memory.c
index ddf20bd..b6bae8f 100644
--- a/mm/memory.c
+++ b/mm/memory.c

@@ -52,6 +52,7 @@
 #include <linux/pagemap.h>
 #include <linux/memremap.h>
 #include <linux/ksm.h>
+#include <linux/kprobes.h>
 #include <linux/rmap.h>
 #include <linux/export.h>
 #include <linux/delayacct.h>

@@ -141,6 +142,21 @@ static int __init init_zero_pfn(void)
 core_initcall(init_zero_pfn);
 
 
+int __kprobes notify_page_fault(struct pt_regs *regs, unsigned int trap)
+{
+	int ret = 0;
+
+	/*
+	 * To be potentially processing a kprobe fault and to be allowed
+	 * to call kprobe_running(), we have to be non-preemptible.
+	 */
+	if (kprobes_built_in() && !preemptible() && !user_mode(regs)) {
+		if (kprobe_running() && kprobe_fault_handler(regs, trap))
+			ret = 1;
+	}
+	return ret;
+}

That thing should be called kprobe_page_fault() or something,
notify_page_fault() is a horribly crap name for this function.

Agreed. kprobe_page_fault() sounds good.