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authorSven Schnelle <svens@stackframe.org>2019-07-23 22:37:54 +0200
committerHelge Deller <deller@gmx.de>2019-07-31 16:20:57 +0200
commit740f05f30a8c49ec63668055d28feedd906d3c50 (patch)
tree7177aaf87236e725de630783278873059f41d023 /arch/parisc/kernel
parentc5df04521b521f14c30de327aa1e880f1190a355 (diff)
parisc: fix race condition in patching code
Assume the following ftrace code sequence that was patched in earlier by ftrace_make_call(): PAGE A: ffc: addr of ftrace_caller() PAGE B: 000: 0x6fc10080 /* stw,ma r1,40(sp) */ 004: 0x48213fd1 /* ldw -18(r1),r1 */ 008: 0xe820c002 /* bv,n r0(r1) */ 00c: 0xe83f1fdf /* b,l,n .-c,r1 */ When a Code sequences that is to be patched spans a page break, we might have already cleared the part on the PAGE A. If an interrupt is coming in during the remap of the fixed mapping to PAGE B, it might execute the patched function with only parts of the FTRACE code cleared. To prevent this, clear the jump to our mini trampoline first, and clear the remaining parts after this. This might also happen when patch_text() patches a function that it calls during remap. Signed-off-by: Sven Schnelle <svens@stackframe.org> Cc: <stable@vger.kernel.org> # 5.2+ Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/kernel')
-rw-r--r--arch/parisc/kernel/ftrace.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/parisc/kernel/ftrace.c b/arch/parisc/kernel/ftrace.c
index d784ccdd8fef..b6fb30f2e4bf 100644
--- a/arch/parisc/kernel/ftrace.c
+++ b/arch/parisc/kernel/ftrace.c
@@ -181,8 +181,9 @@ int ftrace_make_nop(struct module *mod, struct dyn_ftrace *rec,
for (i = 0; i < ARRAY_SIZE(insn); i++)
insn[i] = INSN_NOP;
+ __patch_text((void *)rec->ip, INSN_NOP);
__patch_text_multiple((void *)rec->ip + 4 - sizeof(insn),
- insn, sizeof(insn));
+ insn, sizeof(insn)-4);
return 0;
}
#endif