This patch adds basic sanity tests to ensure that the instruction patching
results in valid instruction encodings. This is done by verifying the output
of the patch process against a vector of assembler generated instructions at
init time.
Signed-off-by: Cyril Chemparathy <cy...@ti.com>
---
arch/arm/Kconfig | 12 ++++++++++++
arch/arm/kernel/runtime-patch.c | 41 +++++++++++++++++++++++++++++++++++++++
2 files changed, 53 insertions(+)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index d0a04ad..7e552dc 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -211,6 +211,18 @@ config ARM_PATCH_PHYS_VIRT
this feature (eg, building a kernel for a single machine) and
you need to shrink the kernel to the minimal size.
+config ARM_RUNTIME_PATCH_TEST
+ bool "Self test runtime patching mechanism" if ARM_RUNTIME_PATCH
+ default y
+ help
+ Select this to enable init time self checking for the runtime kernel
+ patching mechanism. This enables an ISA specific set of tests that
+ ensure that the instructions generated by the patch process are
+ consistent with those generated by the assembler at compile time.
+
+ Only disable this option if you need to shrink the kernel to the
+ minimal size.
+
config NEED_MACH_IO_H
bool
help
diff --git a/arch/arm/kernel/runtime-patch.c b/arch/arm/kernel/runtime-patch.c
index fd37a2b..c471d8c 100644
--- a/arch/arm/kernel/runtime-patch.c
+++ b/arch/arm/kernel/runtime-patch.c
@@ -163,6 +163,44 @@ static int apply_patch_imm8(const struct patch_info *p)
return 0;
}
+#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST
+static void __init __used __naked __patch_test_code_imm8(void)
+{
+ __asm__ __volatile__ (
+ " .irp shift1, 0, 6, 12, 18\n"
+ " .irp shift2, 0, 1, 2, 3, 4, 5\n"
+ " add r1, r2, #(0x41 << (\\shift1 + \\shift2))\n"
+ " .endr\n"
+ " .endr\n"
+ " .word 0\n"
+ : : :
+ );
+}
+
+static void __init test_patch_imm8(void)
+{
+ u32 test_code_addr = (u32)(&__patch_test_code_imm8);
+ u32 *test_code = (u32 *)(test_code_addr & ~0x3);
+ int i, ret;
+ u32 ninsn, insn;
+
+ insn = test_code[0];
+ for (i = 0; test_code[i]; i++) {
+ ret = do_patch_imm8(insn, 0x41 << i, &ninsn);
+ if (ret < 0)
+ pr_err("runtime patch (imm8): failed at shift %d\n", i);
+ else if (ninsn != test_code[i])
+ pr_err("runtime patch (imm8): failed, need %x got %x\n",
+ test_code[i], ninsn);
+ }
+}
+
+static void __init runtime_patch_test(void)
+{
+ test_patch_imm8();
+}
+#endif
+
int runtime_patch(const void *table, unsigned size)
{
const struct patch_info *p = table, *end = (table + size);
@@ -185,5 +223,8 @@ void __init runtime_patch_kernel(void)
const void *start = &__runtime_patch_table_begin;
const void *end = &__runtime_patch_table_end;
+#ifdef CONFIG_ARM_RUNTIME_PATCH_TEST
+ runtime_patch_test();
+#endif
BUG_ON(runtime_patch(start, end - start));
}
--
1.7.9.5
--
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