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authorIngo Molnar <mingo@elte.hu>2009-01-18 18:37:14 +0100
committerIngo Molnar <mingo@elte.hu>2009-01-18 18:37:14 +0100
commitb2b062b8163391c42b3219d466ca1ac9742b9c7b (patch)
treef3f920c09b8de694b1bc1d4b878cfd2b0b98c913 /arch/x86/include/asm/stackprotector.h
parenta9de18eb761f7c1c860964b2e5addc1a35c7e861 (diff)
parent99937d6455cea95405ac681c86a857d0fcd530bd (diff)
Merge branch 'core/percpu' into stackprotector
Conflicts: arch/x86/include/asm/pda.h arch/x86/include/asm/system.h Also, moved include/asm-x86/stackprotector.h to arch/x86/include/asm. Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/stackprotector.h')
-rw-r--r--arch/x86/include/asm/stackprotector.h39
1 files changed, 39 insertions, 0 deletions
diff --git a/arch/x86/include/asm/stackprotector.h b/arch/x86/include/asm/stackprotector.h
new file mode 100644
index 00000000000..c7f0d10bae7
--- /dev/null
+++ b/arch/x86/include/asm/stackprotector.h
@@ -0,0 +1,39 @@
+#ifndef _ASM_STACKPROTECTOR_H
+#define _ASM_STACKPROTECTOR_H 1
+
+#include <asm/tsc.h>
+#include <asm/pda.h>
+
+/*
+ * Initialize the stackprotector canary value.
+ *
+ * NOTE: this must only be called from functions that never return,
+ * and it must always be inlined.
+ */
+static __always_inline void boot_init_stack_canary(void)
+{
+ u64 canary;
+ u64 tsc;
+
+ /*
+ * If we're the non-boot CPU, nothing set the PDA stack
+ * canary up for us - and if we are the boot CPU we have
+ * a 0 stack canary. This is a good place for updating
+ * it, as we wont ever return from this function (so the
+ * invalid canaries already on the stack wont ever
+ * trigger).
+ *
+ * We both use the random pool and the current TSC as a source
+ * of randomness. The TSC only matters for very early init,
+ * there it already has some randomness on most systems. Later
+ * on during the bootup the random pool has true entropy too.
+ */
+ get_random_bytes(&canary, sizeof(canary));
+ tsc = __native_read_tsc();
+ canary += tsc + (tsc << 32UL);
+
+ current->stack_canary = canary;
+ write_pda(stack_canary, canary);
+}
+
+#endif