crypto_gcm_ctx
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(crypto_aead_reqtfm(req));
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(tfm);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(tfm);
inst->alg.base.cra_ctxsize = sizeof(struct crypto_gcm_ctx);
struct crypto_gcm_ctx *ctx = crypto_aead_ctx(aead);