lib/crypto/s390/chacha.h

Source file repositories/reference/linux-study-clean/lib/crypto/s390/chacha.h

File Facts

System
Linux kernel
Corpus path
lib/crypto/s390/chacha.h
Extension
.h
Size
1045 bytes
Lines
37
Domain
Kernel Services
Bucket
lib
Inferred role
Kernel Services: implementation source
Status
source implementation candidate

Why This File Exists

Shared kernel service surface used by multiple subsystems, including helpers, cryptography, virtualization support, and async I/O infrastructure.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/cpufeature.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/sizes.h>
#include <asm/fpu.h>
#include "chacha-s390.h"

#define hchacha_block_arch hchacha_block_generic /* not implemented yet */

static void chacha_crypt_arch(struct chacha_state *state, u8 *dst,
			      const u8 *src, unsigned int bytes, int nrounds)
{
	/* s390 chacha20 implementation has 20 rounds hard-coded,
	 * it cannot handle a block of data or less, but otherwise
	 * it can handle data of arbitrary size
	 */
	if (bytes <= CHACHA_BLOCK_SIZE || nrounds != 20 || !cpu_has_vx()) {
		chacha_crypt_generic(state, dst, src, bytes, nrounds);
	} else {
		DECLARE_KERNEL_FPU_ONSTACK32(vxstate);

		kernel_fpu_begin(&vxstate, KERNEL_VXR);
		chacha20_vx(dst, src, bytes, &state->x[4], &state->x[12]);
		kernel_fpu_end(&vxstate, KERNEL_VXR);

		state->x[12] += round_up(bytes, CHACHA_BLOCK_SIZE) /
				CHACHA_BLOCK_SIZE;
	}
}

Annotation

Implementation Notes