Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

Pull crypto update from Herbert Xu:
 "Here is the crypto update for 3.14:

   - Improved crypto_memneq helper
   - Use cyprto_memneq in arch-specific crypto code
   - Replaced orphaned DCP driver with Freescale MXS DCP driver
   - Added AVX/AVX2 version of AESNI-GCM encode and decode
   - Added AMD Cryptographic Coprocessor (CCP) driver
   - Misc fixes"

* git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (41 commits)
  crypto: aesni - fix build on x86 (32bit)
  crypto: mxs - Fix sparse non static symbol warning
  crypto: ccp - CCP device enabled/disabled changes
  crypto: ccp - Cleanup hash invocation calls
  crypto: ccp - Change data length declarations to u64
  crypto: ccp - Check for caller result area before using it
  crypto: ccp - Cleanup scatterlist usage
  crypto: ccp - Apply appropriate gfp_t type to memory allocations
  crypto: drivers - Sort drivers/crypto/Makefile
  ARM: mxs: dts: Enable DCP for MXS
  crypto: mxs - Add Freescale MXS DCP driver
  crypto: mxs - Remove the old DCP driver
  crypto: ahash - Fully restore ahash request before completing
  crypto: aesni - fix build on x86 (32bit)
  crypto: talitos - Remove redundant dev_set_drvdata
  crypto: ccp - Remove redundant dev_set_drvdata
  crypto: crypto4xx - Remove redundant dev_set_drvdata
  crypto: caam - simplify and harden key parsing
  crypto: omap-sham - Fix Polling mode for larger blocks
  crypto: tcrypt - Added speed tests for AEAD crypto alogrithms in tcrypt test suite
  ...

4 files changed, 551 insertions, 0 deletions

diff --git a/include/linux/ccp.h b/include/linux/ccp.h
new file mode 100644
index 000000000000..b941ab9f762b
--- /dev/null
+++ b/include/linux/ccp.h
@@ -0,0 +1,537 @@
+/*
+ * AMD Cryptographic Coprocessor (CCP) driver
+ *
+ * Copyright (C) 2013 Advanced Micro Devices, Inc.
+ *
+ * Author: Tom Lendacky <thomas.lendacky@amd.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __CPP_H__
+#define __CPP_H__
+
+#include <linux/scatterlist.h>
+#include <linux/workqueue.h>
+#include <linux/list.h>
+#include <crypto/aes.h>
+#include <crypto/sha.h>
+
+
+struct ccp_device;
+struct ccp_cmd;
+
+#if defined(CONFIG_CRYPTO_DEV_CCP_DD) || \
+        defined(CONFIG_CRYPTO_DEV_CCP_DD_MODULE)
+
+/**
+ * ccp_enqueue_cmd - queue an operation for processing by the CCP
+ *
+ * @cmd: ccp_cmd struct to be processed
+ *
+ * Refer to the ccp_cmd struct below for required fields.
+ *
+ * Queue a cmd to be processed by the CCP. If queueing the cmd
+ * would exceed the defined length of the cmd queue the cmd will
+ * only be queued if the CCP_CMD_MAY_BACKLOG flag is set and will
+ * result in a return code of -EBUSY.
+ *
+ * The callback routine specified in the ccp_cmd struct will be
+ * called to notify the caller of completion (if the cmd was not
+ * backlogged) or advancement out of the backlog. If the cmd has
+ * advanced out of the backlog the "err" value of the callback
+ * will be -EINPROGRESS. Any other "err" value during callback is
+ * the result of the operation.
+ *
+ * The cmd has been successfully queued if:
+ *   the return code is -EINPROGRESS or
+ *   the return code is -EBUSY and CCP_CMD_MAY_BACKLOG flag is set
+ */
+int ccp_enqueue_cmd(struct ccp_cmd *cmd);
+
+#else /* CONFIG_CRYPTO_DEV_CCP_DD is not enabled */
+
+static inline int ccp_enqueue_cmd(struct ccp_cmd *cmd)
+{
+        return -ENODEV;
+}
+
+#endif /* CONFIG_CRYPTO_DEV_CCP_DD */
+
+
+/***** AES engine *****/
+/**
+ * ccp_aes_type - AES key size
+ *
+ * @CCP_AES_TYPE_128: 128-bit key
+ * @CCP_AES_TYPE_192: 192-bit key
+ * @CCP_AES_TYPE_256: 256-bit key
+ */
+enum ccp_aes_type {
+        CCP_AES_TYPE_128 = 0,
+        CCP_AES_TYPE_192,
+        CCP_AES_TYPE_256,
+        CCP_AES_TYPE__LAST,
+};
+
+/**
+ * ccp_aes_mode - AES operation mode
+ *
+ * @CCP_AES_MODE_ECB: ECB mode
+ * @CCP_AES_MODE_CBC: CBC mode
+ * @CCP_AES_MODE_OFB: OFB mode
+ * @CCP_AES_MODE_CFB: CFB mode
+ * @CCP_AES_MODE_CTR: CTR mode
+ * @CCP_AES_MODE_CMAC: CMAC mode
+ */
+enum ccp_aes_mode {
+        CCP_AES_MODE_ECB = 0,
+        CCP_AES_MODE_CBC,
+        CCP_AES_MODE_OFB,
+        CCP_AES_MODE_CFB,
+        CCP_AES_MODE_CTR,
+        CCP_AES_MODE_CMAC,
+        CCP_AES_MODE__LAST,
+};
+
+/**
+ * ccp_aes_mode - AES operation mode
+ *
+ * @CCP_AES_ACTION_DECRYPT: AES decrypt operation
+ * @CCP_AES_ACTION_ENCRYPT: AES encrypt operation
+ */
+enum ccp_aes_action {
+        CCP_AES_ACTION_DECRYPT = 0,
+        CCP_AES_ACTION_ENCRYPT,
+        CCP_AES_ACTION__LAST,
+};
+
+/**
+ * struct ccp_aes_engine - CCP AES operation
+ * @type: AES operation key size
+ * @mode: AES operation mode
+ * @action: AES operation (decrypt/encrypt)
+ * @key: key to be used for this AES operation
+ * @key_len: length in bytes of key
+ * @iv: IV to be used for this AES operation
+ * @iv_len: length in bytes of iv
+ * @src: data to be used for this operation
+ * @dst: data produced by this operation
+ * @src_len: length in bytes of data used for this operation
+ * @cmac_final: indicates final operation when running in CMAC mode
+ * @cmac_key: K1/K2 key used in final CMAC operation
+ * @cmac_key_len: length in bytes of cmac_key
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - type, mode, action, key, key_len, src, dst, src_len
+ *   - iv, iv_len for any mode other than ECB
+ *   - cmac_final for CMAC mode
+ *   - cmac_key, cmac_key_len for CMAC mode if cmac_final is non-zero
+ *
+ * The iv variable is used as both input and output. On completion of the
+ * AES operation the new IV overwrites the old IV.
+ */
+struct ccp_aes_engine {
+        enum ccp_aes_type type;
+        enum ccp_aes_mode mode;
+        enum ccp_aes_action action;
+
+        struct scatterlist *key;
+        u32 key_len;            /* In bytes */
+
+        struct scatterlist *iv;
+        u32 iv_len;             /* In bytes */
+
+        struct scatterlist *src, *dst;
+        u64 src_len;            /* In bytes */
+
+        u32 cmac_final;         /* Indicates final cmac cmd */
+        struct scatterlist *cmac_key;   /* K1/K2 cmac key required for
+                                         * final cmac cmd */
+        u32 cmac_key_len;       /* In bytes */
+};
+
+/***** XTS-AES engine *****/
+/**
+ * ccp_xts_aes_unit_size - XTS unit size
+ *
+ * @CCP_XTS_AES_UNIT_SIZE_16: Unit size of 16 bytes
+ * @CCP_XTS_AES_UNIT_SIZE_512: Unit size of 512 bytes
+ * @CCP_XTS_AES_UNIT_SIZE_1024: Unit size of 1024 bytes
+ * @CCP_XTS_AES_UNIT_SIZE_2048: Unit size of 2048 bytes
+ * @CCP_XTS_AES_UNIT_SIZE_4096: Unit size of 4096 bytes
+ */
+enum ccp_xts_aes_unit_size {
+        CCP_XTS_AES_UNIT_SIZE_16 = 0,
+        CCP_XTS_AES_UNIT_SIZE_512,
+        CCP_XTS_AES_UNIT_SIZE_1024,
+        CCP_XTS_AES_UNIT_SIZE_2048,
+        CCP_XTS_AES_UNIT_SIZE_4096,
+        CCP_XTS_AES_UNIT_SIZE__LAST,
+};
+
+/**
+ * struct ccp_xts_aes_engine - CCP XTS AES operation
+ * @action: AES operation (decrypt/encrypt)
+ * @unit_size: unit size of the XTS operation
+ * @key: key to be used for this XTS AES operation
+ * @key_len: length in bytes of key
+ * @iv: IV to be used for this XTS AES operation
+ * @iv_len: length in bytes of iv
+ * @src: data to be used for this operation
+ * @dst: data produced by this operation
+ * @src_len: length in bytes of data used for this operation
+ * @final: indicates final XTS operation
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - action, unit_size, key, key_len, iv, iv_len, src, dst, src_len, final
+ *
+ * The iv variable is used as both input and output. On completion of the
+ * AES operation the new IV overwrites the old IV.
+ */
+struct ccp_xts_aes_engine {
+        enum ccp_aes_action action;
+        enum ccp_xts_aes_unit_size unit_size;
+
+        struct scatterlist *key;
+        u32 key_len;            /* In bytes */
+
+        struct scatterlist *iv;
+        u32 iv_len;             /* In bytes */
+
+        struct scatterlist *src, *dst;
+        u64 src_len;            /* In bytes */
+
+        u32 final;
+};
+
+/***** SHA engine *****/
+#define CCP_SHA_BLOCKSIZE               SHA256_BLOCK_SIZE
+#define CCP_SHA_CTXSIZE                 SHA256_DIGEST_SIZE
+
+/**
+ * ccp_sha_type - type of SHA operation
+ *
+ * @CCP_SHA_TYPE_1: SHA-1 operation
+ * @CCP_SHA_TYPE_224: SHA-224 operation
+ * @CCP_SHA_TYPE_256: SHA-256 operation
+ */
+enum ccp_sha_type {
+        CCP_SHA_TYPE_1 = 1,
+        CCP_SHA_TYPE_224,
+        CCP_SHA_TYPE_256,
+        CCP_SHA_TYPE__LAST,
+};
+
+/**
+ * struct ccp_sha_engine - CCP SHA operation
+ * @type: Type of SHA operation
+ * @ctx: current hash value
+ * @ctx_len: length in bytes of hash value
+ * @src: data to be used for this operation
+ * @src_len: length in bytes of data used for this operation
+ * @final: indicates final SHA operation
+ * @msg_bits: total length of the message in bits used in final SHA operation
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - type, ctx, ctx_len, src, src_len, final
+ *   - msg_bits if final is non-zero
+ *
+ * The ctx variable is used as both input and output. On completion of the
+ * SHA operation the new hash value overwrites the old hash value.
+ */
+struct ccp_sha_engine {
+        enum ccp_sha_type type;
+
+        struct scatterlist *ctx;
+        u32 ctx_len;            /* In bytes */
+
+        struct scatterlist *src;
+        u64 src_len;            /* In bytes */
+
+        u32 final;              /* Indicates final sha cmd */
+        u64 msg_bits;           /* Message length in bits required for
+                                 * final sha cmd */
+};
+
+/***** RSA engine *****/
+/**
+ * struct ccp_rsa_engine - CCP RSA operation
+ * @key_size: length in bits of RSA key
+ * @exp: RSA exponent
+ * @exp_len: length in bytes of exponent
+ * @mod: RSA modulus
+ * @mod_len: length in bytes of modulus
+ * @src: data to be used for this operation
+ * @dst: data produced by this operation
+ * @src_len: length in bytes of data used for this operation
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - key_size, exp, exp_len, mod, mod_len, src, dst, src_len
+ */
+struct ccp_rsa_engine {
+        u32 key_size;           /* In bits */
+
+        struct scatterlist *exp;
+        u32 exp_len;            /* In bytes */
+
+        struct scatterlist *mod;
+        u32 mod_len;            /* In bytes */
+
+        struct scatterlist *src, *dst;
+        u32 src_len;            /* In bytes */
+};
+
+/***** Passthru engine *****/
+/**
+ * ccp_passthru_bitwise - type of bitwise passthru operation
+ *
+ * @CCP_PASSTHRU_BITWISE_NOOP: no bitwise operation performed
+ * @CCP_PASSTHRU_BITWISE_AND: perform bitwise AND of src with mask
+ * @CCP_PASSTHRU_BITWISE_OR: perform bitwise OR of src with mask
+ * @CCP_PASSTHRU_BITWISE_XOR: perform bitwise XOR of src with mask
+ * @CCP_PASSTHRU_BITWISE_MASK: overwrite with mask
+ */
+enum ccp_passthru_bitwise {
+        CCP_PASSTHRU_BITWISE_NOOP = 0,
+        CCP_PASSTHRU_BITWISE_AND,
+        CCP_PASSTHRU_BITWISE_OR,
+        CCP_PASSTHRU_BITWISE_XOR,
+        CCP_PASSTHRU_BITWISE_MASK,
+        CCP_PASSTHRU_BITWISE__LAST,
+};
+
+/**
+ * ccp_passthru_byteswap - type of byteswap passthru operation
+ *
+ * @CCP_PASSTHRU_BYTESWAP_NOOP: no byte swapping performed
+ * @CCP_PASSTHRU_BYTESWAP_32BIT: swap bytes within 32-bit words
+ * @CCP_PASSTHRU_BYTESWAP_256BIT: swap bytes within 256-bit words
+ */
+enum ccp_passthru_byteswap {
+        CCP_PASSTHRU_BYTESWAP_NOOP = 0,
+        CCP_PASSTHRU_BYTESWAP_32BIT,
+        CCP_PASSTHRU_BYTESWAP_256BIT,
+        CCP_PASSTHRU_BYTESWAP__LAST,
+};
+
+/**
+ * struct ccp_passthru_engine - CCP pass-through operation
+ * @bit_mod: bitwise operation to perform
+ * @byte_swap: byteswap operation to perform
+ * @mask: mask to be applied to data
+ * @mask_len: length in bytes of mask
+ * @src: data to be used for this operation
+ * @dst: data produced by this operation
+ * @src_len: length in bytes of data used for this operation
+ * @final: indicate final pass-through operation
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - bit_mod, byte_swap, src, dst, src_len
+ *   - mask, mask_len if bit_mod is not CCP_PASSTHRU_BITWISE_NOOP
+ */
+struct ccp_passthru_engine {
+        enum ccp_passthru_bitwise bit_mod;
+        enum ccp_passthru_byteswap byte_swap;
+
+        struct scatterlist *mask;
+        u32 mask_len;           /* In bytes */
+
+        struct scatterlist *src, *dst;
+        u64 src_len;            /* In bytes */
+
+        u32 final;
+};
+
+/***** ECC engine *****/
+#define CCP_ECC_MODULUS_BYTES   48      /* 384-bits */
+#define CCP_ECC_MAX_OPERANDS    6
+#define CCP_ECC_MAX_OUTPUTS     3
+
+/**
+ * ccp_ecc_function - type of ECC function
+ *
+ * @CCP_ECC_FUNCTION_MMUL_384BIT: 384-bit modular multiplication
+ * @CCP_ECC_FUNCTION_MADD_384BIT: 384-bit modular addition
+ * @CCP_ECC_FUNCTION_MINV_384BIT: 384-bit multiplicative inverse
+ * @CCP_ECC_FUNCTION_PADD_384BIT: 384-bit point addition
+ * @CCP_ECC_FUNCTION_PMUL_384BIT: 384-bit point multiplication
+ * @CCP_ECC_FUNCTION_PDBL_384BIT: 384-bit point doubling
+ */
+enum ccp_ecc_function {
+        CCP_ECC_FUNCTION_MMUL_384BIT = 0,
+        CCP_ECC_FUNCTION_MADD_384BIT,
+        CCP_ECC_FUNCTION_MINV_384BIT,
+        CCP_ECC_FUNCTION_PADD_384BIT,
+        CCP_ECC_FUNCTION_PMUL_384BIT,
+        CCP_ECC_FUNCTION_PDBL_384BIT,
+};
+
+/**
+ * struct ccp_ecc_modular_math - CCP ECC modular math parameters
+ * @operand_1: first operand for the modular math operation
+ * @operand_1_len: length of the first operand
+ * @operand_2: second operand for the modular math operation
+ *             (not used for CCP_ECC_FUNCTION_MINV_384BIT)
+ * @operand_2_len: length of the second operand
+ *             (not used for CCP_ECC_FUNCTION_MINV_384BIT)
+ * @result: result of the modular math operation
+ * @result_len: length of the supplied result buffer
+ */
+struct ccp_ecc_modular_math {
+        struct scatterlist *operand_1;
+        unsigned int operand_1_len;     /* In bytes */
+
+        struct scatterlist *operand_2;
+        unsigned int operand_2_len;     /* In bytes */
+
+        struct scatterlist *result;
+        unsigned int result_len;        /* In bytes */
+};
+
+/**
+ * struct ccp_ecc_point - CCP ECC point definition
+ * @x: the x coordinate of the ECC point
+ * @x_len: the length of the x coordinate
+ * @y: the y coordinate of the ECC point
+ * @y_len: the length of the y coordinate
+ */
+struct ccp_ecc_point {
+        struct scatterlist *x;
+        unsigned int x_len;     /* In bytes */
+
+        struct scatterlist *y;
+        unsigned int y_len;     /* In bytes */
+};
+
+/**
+ * struct ccp_ecc_point_math - CCP ECC point math parameters
+ * @point_1: the first point of the ECC point math operation
+ * @point_2: the second point of the ECC point math operation
+ *           (only used for CCP_ECC_FUNCTION_PADD_384BIT)
+ * @domain_a: the a parameter of the ECC curve
+ * @domain_a_len: the length of the a parameter
+ * @scalar: the scalar parameter for the point match operation
+ *          (only used for CCP_ECC_FUNCTION_PMUL_384BIT)
+ * @scalar_len: the length of the scalar parameter
+ *              (only used for CCP_ECC_FUNCTION_PMUL_384BIT)
+ * @result: the point resulting from the point math operation
+ */
+struct ccp_ecc_point_math {
+        struct ccp_ecc_point point_1;
+        struct ccp_ecc_point point_2;
+
+        struct scatterlist *domain_a;
+        unsigned int domain_a_len;      /* In bytes */
+
+        struct scatterlist *scalar;
+        unsigned int scalar_len;        /* In bytes */
+
+        struct ccp_ecc_point result;
+};
+
+/**
+ * struct ccp_ecc_engine - CCP ECC operation
+ * @function: ECC function to perform
+ * @mod: ECC modulus
+ * @mod_len: length in bytes of modulus
+ * @mm: module math parameters
+ * @pm: point math parameters
+ * @ecc_result: result of the ECC operation
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - function, mod, mod_len
+ *   - operand, operand_len, operand_count, output, output_len, output_count
+ *   - ecc_result
+ */
+struct ccp_ecc_engine {
+        enum ccp_ecc_function function;
+
+        struct scatterlist *mod;
+        u32 mod_len;            /* In bytes */
+
+        union {
+                struct ccp_ecc_modular_math mm;
+                struct ccp_ecc_point_math pm;
+        } u;
+
+        u16 ecc_result;
+};
+
+
+/**
+ * ccp_engine - CCP operation identifiers
+ *
+ * @CCP_ENGINE_AES: AES operation
+ * @CCP_ENGINE_XTS_AES: 128-bit XTS AES operation
+ * @CCP_ENGINE_RSVD1: unused
+ * @CCP_ENGINE_SHA: SHA operation
+ * @CCP_ENGINE_RSA: RSA operation
+ * @CCP_ENGINE_PASSTHRU: pass-through operation
+ * @CCP_ENGINE_ZLIB_DECOMPRESS: unused
+ * @CCP_ENGINE_ECC: ECC operation
+ */
+enum ccp_engine {
+        CCP_ENGINE_AES = 0,
+        CCP_ENGINE_XTS_AES_128,
+        CCP_ENGINE_RSVD1,
+        CCP_ENGINE_SHA,
+        CCP_ENGINE_RSA,
+        CCP_ENGINE_PASSTHRU,
+        CCP_ENGINE_ZLIB_DECOMPRESS,
+        CCP_ENGINE_ECC,
+        CCP_ENGINE__LAST,
+};
+
+/* Flag values for flags member of ccp_cmd */
+#define CCP_CMD_MAY_BACKLOG     0x00000001
+
+/**
+ * struct ccp_cmd - CPP operation request
+ * @entry: list element (ccp driver use only)
+ * @work: work element used for callbacks (ccp driver use only)
+ * @ccp: CCP device to be run on (ccp driver use only)
+ * @ret: operation return code (ccp driver use only)
+ * @flags: cmd processing flags
+ * @engine: CCP operation to perform
+ * @engine_error: CCP engine return code
+ * @u: engine specific structures, refer to specific engine struct below
+ * @callback: operation completion callback function
+ * @data: parameter value to be supplied to the callback function
+ *
+ * Variables required to be set when calling ccp_enqueue_cmd():
+ *   - engine, callback
+ *   - See the operation structures below for what is required for each
+ *     operation.
+ */
+struct ccp_cmd {
+        /* The list_head, work_struct, ccp and ret variables are for use
+         * by the CCP driver only.
+         */
+        struct list_head entry;
+        struct work_struct work;
+        struct ccp_device *ccp;
+        int ret;
+
+        u32 flags;
+
+        enum ccp_engine engine;
+        u32 engine_error;
+
+        union {
+                struct ccp_aes_engine aes;
+                struct ccp_xts_aes_engine xts;
+                struct ccp_sha_engine sha;
+                struct ccp_rsa_engine rsa;
+                struct ccp_passthru_engine passthru;
+                struct ccp_ecc_engine ecc;
+        } u;
+
+        /* Completion callback support */
+        void (*callback)(void *data, int err);
+        void *data;
+};
+
+#endif
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h
index 24545cd90a25..02ae99e8e6d3 100644
--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -37,6 +37,9 @@
     __asm__ ("" : "=r"(__ptr) : "0"(ptr));              \
     (typeof(ptr)) (__ptr + (off)); })
 
+/* Make the optimizer believe the variable can be manipulated arbitrarily. */
+#define OPTIMIZER_HIDE_VAR(var) __asm__ ("" : "=r" (var) : "0" (var))
+
 #ifdef __CHECKER__
 #define __must_be_array(arr) 0
 #else
diff --git a/include/linux/compiler-intel.h b/include/linux/compiler-intel.h
index dc1bd3dcf11f..5529c5239421 100644
--- a/include/linux/compiler-intel.h
+++ b/include/linux/compiler-intel.h
@@ -15,6 +15,7 @@
  */
 #undef barrier
 #undef RELOC_HIDE
+#undef OPTIMIZER_HIDE_VAR
 
 #define barrier() __memory_barrier()
 
@@ -23,6 +24,12 @@
      __ptr = (unsigned long) (ptr);                             \
     (typeof(ptr)) (__ptr + (off)); })
 
+/* This should act as an optimization barrier on var.
+ * Given that this compiler does not have inline assembly, a compiler barrier
+ * is the best we can do.
+ */
+#define OPTIMIZER_HIDE_VAR(var) barrier()
+
 /* Intel ECC compiler doesn't support __builtin_types_compatible_p() */
 #define __must_be_array(a) 0
 
diff --git a/include/linux/compiler.h b/include/linux/compiler.h
index fe7a686dfd8d..2472740d7ab2 100644
--- a/include/linux/compiler.h
+++ b/include/linux/compiler.h
@@ -170,6 +170,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect);
     (typeof(ptr)) (__ptr + (off)); })
 #endif
 
+#ifndef OPTIMIZER_HIDE_VAR
+#define OPTIMIZER_HIDE_VAR(var) barrier()
+#endif
+
 /* Not-quite-unique ID. */
 #ifndef __UNIQUE_ID
 # define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __LINE__)