[tip:perf/urgent] uprobes: Fix uprobes on MIPS, allow for a cache flush after ixol breakpoint creation

[tip-bot for Marcin Nowakowski <tipbot@zytor.com>]

Commit-ID:  297e765e390a2ac996000b5f7228cbd84d995174
Gitweb:     http://git.kernel.org/tip/297e765e390a2ac996000b5f7228cbd84d995174
Author:     Marcin Nowakowski <marcin.nowakowski@imgtec.com>
AuthorDate: Tue, 13 Dec 2016 11:40:57 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 18 Dec 2016 09:42:11 +0100

uprobes: Fix uprobes on MIPS, allow for a cache flush after ixol breakpoint creation

Commit:

  72e6ae285a1d ('ARM: 8043/1: uprobes need icache flush after xol write'

... has introduced an arch-specific method to ensure all caches are
flushed appropriately after an instruction is written to an XOL page.

However, when the XOL area is created and the out-of-line breakpoint
instruction is copied, caches are not flushed at all and stale data may
be found in icache.

Replace a simple copy_to_page() with arch_uprobe_copy_ixol() to allow
the arch to ensure all caches are updated accordingly.

This change fixes uprobes on MIPS InterAptiv (tested on Creator Ci40).

Signed-off-by: Marcin Nowakowski <marcin.nowakowski@imgtec.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Victor Kamensky <victor.kamensky@linaro.org>
Cc: linux-mips@linux-mips.org
Link: http://lkml.kernel.org/r/1481625657-22850-1-git-send-email-marcin.nowakowski@imgtec.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 kernel/events/uprobes.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index f9ec9ad..b5916b4 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1194,7 +1194,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
 	/* Reserve the 1st slot for get_trampoline_vaddr() */
 	set_bit(0, area->bitmap);
 	atomic_set(&area->slot_count, 1);
-	copy_to_page(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE);
+	arch_uprobe_copy_ixol(area->pages[0], 0, &insn, UPROBE_SWBP_INSN_SIZE);
 
 	if (!xol_add_vma(mm, area))
 		return area;