From: Benjamin Berg <benjamin.berg@intel.com>
Date: Sun, 3 Nov 2024 15:05:02 +0000 (+0100)
Subject: um: set DONTDUMP and DONTFORK flags on KASAN shadow memory
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=fce0128863b22dd6d9a4e5383645ac70656970a7;p=users%2Fjedix%2Flinux-maple.git

um: set DONTDUMP and DONTFORK flags on KASAN shadow memory

There is no point in either dumping the KASAN shadow memory or doing
copy-on-write after a fork on these memory regions.

This considerably speeds up coredump generation.

Signed-off-by: Benjamin Berg <benjamin.berg@intel.com>
Link: https://patch.msgid.link/20241103150506.1367695-1-benjamin@sipsolutions.net
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
---

diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 857e3deab2935..72f302f4d197f 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -39,6 +39,18 @@ void kasan_map_memory(void *start, size_t len)
 			strerror(errno));
 		exit(1);
 	}
+
+	if (madvise(start, len, MADV_DONTDUMP)) {
+		os_info("Couldn't set MAD_DONTDUMP on shadow memory: %s\n.",
+			strerror(errno));
+		exit(1);
+	}
+
+	if (madvise(start, len, MADV_DONTFORK)) {
+		os_info("Couldn't set MADV_DONTFORK on shadow memory: %s\n.",
+			strerror(errno));
+		exit(1);
+	}
 }
 
 /* Set by make_tempfile() during early boot. */