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authorArd Biesheuvel <ard.biesheuvel@linaro.org>2018-09-19 09:51:37 +0300
committerThomas Gleixner <tglx@linutronix.de>2018-09-27 18:56:47 +0300
commit50ff18ab497aa22f6a59444625df7508c8918237 (patch)
treee3d2dd15c0a13765fc242bb908c9cd91da48a951 /kernel/jump_label.c
parent9ae033aca8d600e36034d4d0743aad624cec92ed (diff)
downloadlinux-50ff18ab497aa22f6a59444625df7508c8918237.tar.xz
jump_label: Implement generic support for relative references
To reduce the size taken up by absolute references in jump label entries themselves and the associated relocation records in the .init segment, add support for emitting them as relative references instead. Note that this requires some extra care in the sorting routine, given that the offsets change when entries are moved around in the jump_entry table. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: linux-arm-kernel@lists.infradead.org Cc: linux-s390@vger.kernel.org Cc: Arnd Bergmann <arnd@arndb.de> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Kees Cook <keescook@chromium.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Jessica Yu <jeyu@kernel.org> Link: https://lkml.kernel.org/r/20180919065144.25010-3-ard.biesheuvel@linaro.org
Diffstat (limited to 'kernel/jump_label.c')
-rw-r--r--kernel/jump_label.c22
1 files changed, 21 insertions, 1 deletions
diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index 834e43de0daf..898a1d0c38dc 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -47,14 +47,34 @@ static int jump_label_cmp(const void *a, const void *b)
return 0;
}
+static void jump_label_swap(void *a, void *b, int size)
+{
+ long delta = (unsigned long)a - (unsigned long)b;
+ struct jump_entry *jea = a;
+ struct jump_entry *jeb = b;
+ struct jump_entry tmp = *jea;
+
+ jea->code = jeb->code - delta;
+ jea->target = jeb->target - delta;
+ jea->key = jeb->key - delta;
+
+ jeb->code = tmp.code + delta;
+ jeb->target = tmp.target + delta;
+ jeb->key = tmp.key + delta;
+}
+
static void
jump_label_sort_entries(struct jump_entry *start, struct jump_entry *stop)
{
unsigned long size;
+ void *swapfn = NULL;
+
+ if (IS_ENABLED(CONFIG_HAVE_ARCH_JUMP_LABEL_RELATIVE))
+ swapfn = jump_label_swap;
size = (((unsigned long)stop - (unsigned long)start)
/ sizeof(struct jump_entry));
- sort(start, size, sizeof(struct jump_entry), jump_label_cmp, NULL);
+ sort(start, size, sizeof(struct jump_entry), jump_label_cmp, swapfn);
}
static void jump_label_update(struct static_key *key);