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