Revision 63cae12bce9861cec309798d34701cf3da20bc71 authored by Peter Zijlstra on 09 December 2016, 13:59:00 UTC, committed by Ingo Molnar on 14 January 2017, 09:56:10 UTC
There is problem with installing an event in a task that is 'stuck' on
an offline CPU.

Blocked tasks are not dis-assosciated from offlined CPUs, after all, a
blocked task doesn't run and doesn't require a CPU etc.. Only on
wakeup do we ammend the situation and place the task on a available
CPU.

If we hit such a task with perf_install_in_context() we'll loop until
either that task wakes up or the CPU comes back online, if the task
waking depends on the event being installed, we're stuck.

While looking into this issue, I also spotted another problem, if we
hit a task with perf_install_in_context() that is in the middle of
being migrated, that is we observe the old CPU before sending the IPI,
but run the IPI (on the old CPU) while the task is already running on
the new CPU, things also go sideways.

Rework things to rely on task_curr() -- outside of rq->lock -- which
is rather tricky. Imagine the following scenario where we're trying to
install the first event into our task 't':

CPU0            CPU1            CPU2

                (current == t)

t->perf_event_ctxp[] = ctx;
smp_mb();
cpu = task_cpu(t);

                switch(t, n);
                                migrate(t, 2);
                                switch(p, t);

                                ctx = t->perf_event_ctxp[]; // must not be NULL

smp_function_call(cpu, ..);

                generic_exec_single()
                  func();
                    spin_lock(ctx->lock);
                    if (task_curr(t)) // false

                    add_event_to_ctx();
                    spin_unlock(ctx->lock);

                                perf_event_context_sched_in();
                                  spin_lock(ctx->lock);
                                  // sees event

So its CPU0's store of t->perf_event_ctxp[] that must not go 'missing'.
Because if CPU2's load of that variable were to observe NULL, it would
not try to schedule the ctx and we'd have a task running without its
counter, which would be 'bad'.

As long as we observe !NULL, we'll acquire ctx->lock. If we acquire it
first and not see the event yet, then CPU0 must observe task_curr()
and retry. If the install happens first, then we must see the event on
sched-in and all is well.

I think we can translate the first part (until the 'must not be NULL')
of the scenario to a litmus test like:

  C C-peterz

  {
  }

  P0(int *x, int *y)
  {
          int r1;

          WRITE_ONCE(*x, 1);
          smp_mb();
          r1 = READ_ONCE(*y);
  }

  P1(int *y, int *z)
  {
          WRITE_ONCE(*y, 1);
          smp_store_release(z, 1);
  }

  P2(int *x, int *z)
  {
          int r1;
          int r2;

          r1 = smp_load_acquire(z);
	  smp_mb();
          r2 = READ_ONCE(*x);
  }

  exists
  (0:r1=0 /\ 2:r1=1 /\ 2:r2=0)

Where:
  x is perf_event_ctxp[],
  y is our tasks's CPU, and
  z is our task being placed on the rq of CPU2.

The P0 smp_mb() is the one added by this patch, ordering the store to
perf_event_ctxp[] from find_get_context() and the load of task_cpu()
in task_function_call().

The smp_store_release/smp_load_acquire model the RCpc locking of the
rq->lock and the smp_mb() of P2 is the context switch switching from
whatever CPU2 was running to our task 't'.

This litmus test evaluates into:

  Test C-peterz Allowed
  States 7
  0:r1=0; 2:r1=0; 2:r2=0;
  0:r1=0; 2:r1=0; 2:r2=1;
  0:r1=0; 2:r1=1; 2:r2=1;
  0:r1=1; 2:r1=0; 2:r2=0;
  0:r1=1; 2:r1=0; 2:r2=1;
  0:r1=1; 2:r1=1; 2:r2=0;
  0:r1=1; 2:r1=1; 2:r2=1;
  No
  Witnesses
  Positive: 0 Negative: 7
  Condition exists (0:r1=0 /\ 2:r1=1 /\ 2:r2=0)
  Observation C-peterz Never 0 7
  Hash=e427f41d9146b2a5445101d3e2fcaa34

And the strong and weak model agree.

Reported-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: Will Deacon <will.deacon@arm.com>
Cc: jeremy.linton@arm.com
Link: http://lkml.kernel.org/r/20161209135900.GU3174@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
1 parent ad5013d
Raw File
rmd160.c
/*
 * Cryptographic API.
 *
 * RIPEMD-160 - RACE Integrity Primitives Evaluation Message Digest.
 *
 * Based on the reference implementation by Antoon Bosselaers, ESAT-COSIC
 *
 * Copyright (c) 2008 Adrian-Ken Rueegsegger <ken@codelabs.ch>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 2 of the License, or (at your option)
 * any later version.
 *
 */
#include <crypto/internal/hash.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/types.h>
#include <asm/byteorder.h>

#include "ripemd.h"

struct rmd160_ctx {
	u64 byte_count;
	u32 state[5];
	__le32 buffer[16];
};

#define K1  RMD_K1
#define K2  RMD_K2
#define K3  RMD_K3
#define K4  RMD_K4
#define K5  RMD_K5
#define KK1 RMD_K6
#define KK2 RMD_K7
#define KK3 RMD_K8
#define KK4 RMD_K9
#define KK5 RMD_K1

#define F1(x, y, z) (x ^ y ^ z)		/* XOR */
#define F2(x, y, z) (z ^ (x & (y ^ z)))	/* x ? y : z */
#define F3(x, y, z) ((x | ~y) ^ z)
#define F4(x, y, z) (y ^ (z & (x ^ y)))	/* z ? x : y */
#define F5(x, y, z) (x ^ (y | ~z))

#define ROUND(a, b, c, d, e, f, k, x, s)  { \
	(a) += f((b), (c), (d)) + le32_to_cpup(&(x)) + (k); \
	(a) = rol32((a), (s)) + (e); \
	(c) = rol32((c), 10); \
}

static void rmd160_transform(u32 *state, const __le32 *in)
{
	u32 aa, bb, cc, dd, ee, aaa, bbb, ccc, ddd, eee;

	/* Initialize left lane */
	aa = state[0];
	bb = state[1];
	cc = state[2];
	dd = state[3];
	ee = state[4];

	/* Initialize right lane */
	aaa = state[0];
	bbb = state[1];
	ccc = state[2];
	ddd = state[3];
	eee = state[4];

	/* round 1: left lane */
	ROUND(aa, bb, cc, dd, ee, F1, K1, in[0],  11);
	ROUND(ee, aa, bb, cc, dd, F1, K1, in[1],  14);
	ROUND(dd, ee, aa, bb, cc, F1, K1, in[2],  15);
	ROUND(cc, dd, ee, aa, bb, F1, K1, in[3],  12);
	ROUND(bb, cc, dd, ee, aa, F1, K1, in[4],   5);
	ROUND(aa, bb, cc, dd, ee, F1, K1, in[5],   8);
	ROUND(ee, aa, bb, cc, dd, F1, K1, in[6],   7);
	ROUND(dd, ee, aa, bb, cc, F1, K1, in[7],   9);
	ROUND(cc, dd, ee, aa, bb, F1, K1, in[8],  11);
	ROUND(bb, cc, dd, ee, aa, F1, K1, in[9],  13);
	ROUND(aa, bb, cc, dd, ee, F1, K1, in[10], 14);
	ROUND(ee, aa, bb, cc, dd, F1, K1, in[11], 15);
	ROUND(dd, ee, aa, bb, cc, F1, K1, in[12],  6);
	ROUND(cc, dd, ee, aa, bb, F1, K1, in[13],  7);
	ROUND(bb, cc, dd, ee, aa, F1, K1, in[14],  9);
	ROUND(aa, bb, cc, dd, ee, F1, K1, in[15],  8);

	/* round 2: left lane" */
	ROUND(ee, aa, bb, cc, dd, F2, K2, in[7],   7);
	ROUND(dd, ee, aa, bb, cc, F2, K2, in[4],   6);
	ROUND(cc, dd, ee, aa, bb, F2, K2, in[13],  8);
	ROUND(bb, cc, dd, ee, aa, F2, K2, in[1],  13);
	ROUND(aa, bb, cc, dd, ee, F2, K2, in[10], 11);
	ROUND(ee, aa, bb, cc, dd, F2, K2, in[6],   9);
	ROUND(dd, ee, aa, bb, cc, F2, K2, in[15],  7);
	ROUND(cc, dd, ee, aa, bb, F2, K2, in[3],  15);
	ROUND(bb, cc, dd, ee, aa, F2, K2, in[12],  7);
	ROUND(aa, bb, cc, dd, ee, F2, K2, in[0],  12);
	ROUND(ee, aa, bb, cc, dd, F2, K2, in[9],  15);
	ROUND(dd, ee, aa, bb, cc, F2, K2, in[5],   9);
	ROUND(cc, dd, ee, aa, bb, F2, K2, in[2],  11);
	ROUND(bb, cc, dd, ee, aa, F2, K2, in[14],  7);
	ROUND(aa, bb, cc, dd, ee, F2, K2, in[11], 13);
	ROUND(ee, aa, bb, cc, dd, F2, K2, in[8],  12);

	/* round 3: left lane" */
	ROUND(dd, ee, aa, bb, cc, F3, K3, in[3],  11);
	ROUND(cc, dd, ee, aa, bb, F3, K3, in[10], 13);
	ROUND(bb, cc, dd, ee, aa, F3, K3, in[14],  6);
	ROUND(aa, bb, cc, dd, ee, F3, K3, in[4],   7);
	ROUND(ee, aa, bb, cc, dd, F3, K3, in[9],  14);
	ROUND(dd, ee, aa, bb, cc, F3, K3, in[15],  9);
	ROUND(cc, dd, ee, aa, bb, F3, K3, in[8],  13);
	ROUND(bb, cc, dd, ee, aa, F3, K3, in[1],  15);
	ROUND(aa, bb, cc, dd, ee, F3, K3, in[2],  14);
	ROUND(ee, aa, bb, cc, dd, F3, K3, in[7],   8);
	ROUND(dd, ee, aa, bb, cc, F3, K3, in[0],  13);
	ROUND(cc, dd, ee, aa, bb, F3, K3, in[6],   6);
	ROUND(bb, cc, dd, ee, aa, F3, K3, in[13],  5);
	ROUND(aa, bb, cc, dd, ee, F3, K3, in[11], 12);
	ROUND(ee, aa, bb, cc, dd, F3, K3, in[5],   7);
	ROUND(dd, ee, aa, bb, cc, F3, K3, in[12],  5);

	/* round 4: left lane" */
	ROUND(cc, dd, ee, aa, bb, F4, K4, in[1],  11);
	ROUND(bb, cc, dd, ee, aa, F4, K4, in[9],  12);
	ROUND(aa, bb, cc, dd, ee, F4, K4, in[11], 14);
	ROUND(ee, aa, bb, cc, dd, F4, K4, in[10], 15);
	ROUND(dd, ee, aa, bb, cc, F4, K4, in[0],  14);
	ROUND(cc, dd, ee, aa, bb, F4, K4, in[8],  15);
	ROUND(bb, cc, dd, ee, aa, F4, K4, in[12],  9);
	ROUND(aa, bb, cc, dd, ee, F4, K4, in[4],   8);
	ROUND(ee, aa, bb, cc, dd, F4, K4, in[13],  9);
	ROUND(dd, ee, aa, bb, cc, F4, K4, in[3],  14);
	ROUND(cc, dd, ee, aa, bb, F4, K4, in[7],   5);
	ROUND(bb, cc, dd, ee, aa, F4, K4, in[15],  6);
	ROUND(aa, bb, cc, dd, ee, F4, K4, in[14],  8);
	ROUND(ee, aa, bb, cc, dd, F4, K4, in[5],   6);
	ROUND(dd, ee, aa, bb, cc, F4, K4, in[6],   5);
	ROUND(cc, dd, ee, aa, bb, F4, K4, in[2],  12);

	/* round 5: left lane" */
	ROUND(bb, cc, dd, ee, aa, F5, K5, in[4],   9);
	ROUND(aa, bb, cc, dd, ee, F5, K5, in[0],  15);
	ROUND(ee, aa, bb, cc, dd, F5, K5, in[5],   5);
	ROUND(dd, ee, aa, bb, cc, F5, K5, in[9],  11);
	ROUND(cc, dd, ee, aa, bb, F5, K5, in[7],   6);
	ROUND(bb, cc, dd, ee, aa, F5, K5, in[12],  8);
	ROUND(aa, bb, cc, dd, ee, F5, K5, in[2],  13);
	ROUND(ee, aa, bb, cc, dd, F5, K5, in[10], 12);
	ROUND(dd, ee, aa, bb, cc, F5, K5, in[14],  5);
	ROUND(cc, dd, ee, aa, bb, F5, K5, in[1],  12);
	ROUND(bb, cc, dd, ee, aa, F5, K5, in[3],  13);
	ROUND(aa, bb, cc, dd, ee, F5, K5, in[8],  14);
	ROUND(ee, aa, bb, cc, dd, F5, K5, in[11], 11);
	ROUND(dd, ee, aa, bb, cc, F5, K5, in[6],   8);
	ROUND(cc, dd, ee, aa, bb, F5, K5, in[15],  5);
	ROUND(bb, cc, dd, ee, aa, F5, K5, in[13],  6);

	/* round 1: right lane */
	ROUND(aaa, bbb, ccc, ddd, eee, F5, KK1, in[5],   8);
	ROUND(eee, aaa, bbb, ccc, ddd, F5, KK1, in[14],  9);
	ROUND(ddd, eee, aaa, bbb, ccc, F5, KK1, in[7],   9);
	ROUND(ccc, ddd, eee, aaa, bbb, F5, KK1, in[0],  11);
	ROUND(bbb, ccc, ddd, eee, aaa, F5, KK1, in[9],  13);
	ROUND(aaa, bbb, ccc, ddd, eee, F5, KK1, in[2],  15);
	ROUND(eee, aaa, bbb, ccc, ddd, F5, KK1, in[11], 15);
	ROUND(ddd, eee, aaa, bbb, ccc, F5, KK1, in[4],   5);
	ROUND(ccc, ddd, eee, aaa, bbb, F5, KK1, in[13],  7);
	ROUND(bbb, ccc, ddd, eee, aaa, F5, KK1, in[6],   7);
	ROUND(aaa, bbb, ccc, ddd, eee, F5, KK1, in[15],  8);
	ROUND(eee, aaa, bbb, ccc, ddd, F5, KK1, in[8],  11);
	ROUND(ddd, eee, aaa, bbb, ccc, F5, KK1, in[1],  14);
	ROUND(ccc, ddd, eee, aaa, bbb, F5, KK1, in[10], 14);
	ROUND(bbb, ccc, ddd, eee, aaa, F5, KK1, in[3],  12);
	ROUND(aaa, bbb, ccc, ddd, eee, F5, KK1, in[12],  6);

	/* round 2: right lane */
	ROUND(eee, aaa, bbb, ccc, ddd, F4, KK2, in[6],   9);
	ROUND(ddd, eee, aaa, bbb, ccc, F4, KK2, in[11], 13);
	ROUND(ccc, ddd, eee, aaa, bbb, F4, KK2, in[3],  15);
	ROUND(bbb, ccc, ddd, eee, aaa, F4, KK2, in[7],   7);
	ROUND(aaa, bbb, ccc, ddd, eee, F4, KK2, in[0],  12);
	ROUND(eee, aaa, bbb, ccc, ddd, F4, KK2, in[13],  8);
	ROUND(ddd, eee, aaa, bbb, ccc, F4, KK2, in[5],   9);
	ROUND(ccc, ddd, eee, aaa, bbb, F4, KK2, in[10], 11);
	ROUND(bbb, ccc, ddd, eee, aaa, F4, KK2, in[14],  7);
	ROUND(aaa, bbb, ccc, ddd, eee, F4, KK2, in[15],  7);
	ROUND(eee, aaa, bbb, ccc, ddd, F4, KK2, in[8],  12);
	ROUND(ddd, eee, aaa, bbb, ccc, F4, KK2, in[12],  7);
	ROUND(ccc, ddd, eee, aaa, bbb, F4, KK2, in[4],   6);
	ROUND(bbb, ccc, ddd, eee, aaa, F4, KK2, in[9],  15);
	ROUND(aaa, bbb, ccc, ddd, eee, F4, KK2, in[1],  13);
	ROUND(eee, aaa, bbb, ccc, ddd, F4, KK2, in[2],  11);

	/* round 3: right lane */
	ROUND(ddd, eee, aaa, bbb, ccc, F3, KK3, in[15],  9);
	ROUND(ccc, ddd, eee, aaa, bbb, F3, KK3, in[5],   7);
	ROUND(bbb, ccc, ddd, eee, aaa, F3, KK3, in[1],  15);
	ROUND(aaa, bbb, ccc, ddd, eee, F3, KK3, in[3],  11);
	ROUND(eee, aaa, bbb, ccc, ddd, F3, KK3, in[7],   8);
	ROUND(ddd, eee, aaa, bbb, ccc, F3, KK3, in[14],  6);
	ROUND(ccc, ddd, eee, aaa, bbb, F3, KK3, in[6],   6);
	ROUND(bbb, ccc, ddd, eee, aaa, F3, KK3, in[9],  14);
	ROUND(aaa, bbb, ccc, ddd, eee, F3, KK3, in[11], 12);
	ROUND(eee, aaa, bbb, ccc, ddd, F3, KK3, in[8],  13);
	ROUND(ddd, eee, aaa, bbb, ccc, F3, KK3, in[12],  5);
	ROUND(ccc, ddd, eee, aaa, bbb, F3, KK3, in[2],  14);
	ROUND(bbb, ccc, ddd, eee, aaa, F3, KK3, in[10], 13);
	ROUND(aaa, bbb, ccc, ddd, eee, F3, KK3, in[0],  13);
	ROUND(eee, aaa, bbb, ccc, ddd, F3, KK3, in[4],   7);
	ROUND(ddd, eee, aaa, bbb, ccc, F3, KK3, in[13],  5);

	/* round 4: right lane */
	ROUND(ccc, ddd, eee, aaa, bbb, F2, KK4, in[8],  15);
	ROUND(bbb, ccc, ddd, eee, aaa, F2, KK4, in[6],   5);
	ROUND(aaa, bbb, ccc, ddd, eee, F2, KK4, in[4],   8);
	ROUND(eee, aaa, bbb, ccc, ddd, F2, KK4, in[1],  11);
	ROUND(ddd, eee, aaa, bbb, ccc, F2, KK4, in[3],  14);
	ROUND(ccc, ddd, eee, aaa, bbb, F2, KK4, in[11], 14);
	ROUND(bbb, ccc, ddd, eee, aaa, F2, KK4, in[15],  6);
	ROUND(aaa, bbb, ccc, ddd, eee, F2, KK4, in[0],  14);
	ROUND(eee, aaa, bbb, ccc, ddd, F2, KK4, in[5],   6);
	ROUND(ddd, eee, aaa, bbb, ccc, F2, KK4, in[12],  9);
	ROUND(ccc, ddd, eee, aaa, bbb, F2, KK4, in[2],  12);
	ROUND(bbb, ccc, ddd, eee, aaa, F2, KK4, in[13],  9);
	ROUND(aaa, bbb, ccc, ddd, eee, F2, KK4, in[9],  12);
	ROUND(eee, aaa, bbb, ccc, ddd, F2, KK4, in[7],   5);
	ROUND(ddd, eee, aaa, bbb, ccc, F2, KK4, in[10], 15);
	ROUND(ccc, ddd, eee, aaa, bbb, F2, KK4, in[14],  8);

	/* round 5: right lane */
	ROUND(bbb, ccc, ddd, eee, aaa, F1, KK5, in[12],  8);
	ROUND(aaa, bbb, ccc, ddd, eee, F1, KK5, in[15],  5);
	ROUND(eee, aaa, bbb, ccc, ddd, F1, KK5, in[10], 12);
	ROUND(ddd, eee, aaa, bbb, ccc, F1, KK5, in[4],   9);
	ROUND(ccc, ddd, eee, aaa, bbb, F1, KK5, in[1],  12);
	ROUND(bbb, ccc, ddd, eee, aaa, F1, KK5, in[5],   5);
	ROUND(aaa, bbb, ccc, ddd, eee, F1, KK5, in[8],  14);
	ROUND(eee, aaa, bbb, ccc, ddd, F1, KK5, in[7],   6);
	ROUND(ddd, eee, aaa, bbb, ccc, F1, KK5, in[6],   8);
	ROUND(ccc, ddd, eee, aaa, bbb, F1, KK5, in[2],  13);
	ROUND(bbb, ccc, ddd, eee, aaa, F1, KK5, in[13],  6);
	ROUND(aaa, bbb, ccc, ddd, eee, F1, KK5, in[14],  5);
	ROUND(eee, aaa, bbb, ccc, ddd, F1, KK5, in[0],  15);
	ROUND(ddd, eee, aaa, bbb, ccc, F1, KK5, in[3],  13);
	ROUND(ccc, ddd, eee, aaa, bbb, F1, KK5, in[9],  11);
	ROUND(bbb, ccc, ddd, eee, aaa, F1, KK5, in[11], 11);

	/* combine results */
	ddd += cc + state[1];		/* final result for state[0] */
	state[1] = state[2] + dd + eee;
	state[2] = state[3] + ee + aaa;
	state[3] = state[4] + aa + bbb;
	state[4] = state[0] + bb + ccc;
	state[0] = ddd;

	return;
}

static int rmd160_init(struct shash_desc *desc)
{
	struct rmd160_ctx *rctx = shash_desc_ctx(desc);

	rctx->byte_count = 0;

	rctx->state[0] = RMD_H0;
	rctx->state[1] = RMD_H1;
	rctx->state[2] = RMD_H2;
	rctx->state[3] = RMD_H3;
	rctx->state[4] = RMD_H4;

	memset(rctx->buffer, 0, sizeof(rctx->buffer));

	return 0;
}

static int rmd160_update(struct shash_desc *desc, const u8 *data,
			 unsigned int len)
{
	struct rmd160_ctx *rctx = shash_desc_ctx(desc);
	const u32 avail = sizeof(rctx->buffer) - (rctx->byte_count & 0x3f);

	rctx->byte_count += len;

	/* Enough space in buffer? If so copy and we're done */
	if (avail > len) {
		memcpy((char *)rctx->buffer + (sizeof(rctx->buffer) - avail),
		       data, len);
		goto out;
	}

	memcpy((char *)rctx->buffer + (sizeof(rctx->buffer) - avail),
	       data, avail);

	rmd160_transform(rctx->state, rctx->buffer);
	data += avail;
	len -= avail;

	while (len >= sizeof(rctx->buffer)) {
		memcpy(rctx->buffer, data, sizeof(rctx->buffer));
		rmd160_transform(rctx->state, rctx->buffer);
		data += sizeof(rctx->buffer);
		len -= sizeof(rctx->buffer);
	}

	memcpy(rctx->buffer, data, len);

out:
	return 0;
}

/* Add padding and return the message digest. */
static int rmd160_final(struct shash_desc *desc, u8 *out)
{
	struct rmd160_ctx *rctx = shash_desc_ctx(desc);
	u32 i, index, padlen;
	__le64 bits;
	__le32 *dst = (__le32 *)out;
	static const u8 padding[64] = { 0x80, };

	bits = cpu_to_le64(rctx->byte_count << 3);

	/* Pad out to 56 mod 64 */
	index = rctx->byte_count & 0x3f;
	padlen = (index < 56) ? (56 - index) : ((64+56) - index);
	rmd160_update(desc, padding, padlen);

	/* Append length */
	rmd160_update(desc, (const u8 *)&bits, sizeof(bits));

	/* Store state in digest */
	for (i = 0; i < 5; i++)
		dst[i] = cpu_to_le32p(&rctx->state[i]);

	/* Wipe context */
	memset(rctx, 0, sizeof(*rctx));

	return 0;
}

static struct shash_alg alg = {
	.digestsize	=	RMD160_DIGEST_SIZE,
	.init		=	rmd160_init,
	.update		=	rmd160_update,
	.final		=	rmd160_final,
	.descsize	=	sizeof(struct rmd160_ctx),
	.base		=	{
		.cra_name	 =	"rmd160",
		.cra_flags	 =	CRYPTO_ALG_TYPE_SHASH,
		.cra_blocksize	 =	RMD160_BLOCK_SIZE,
		.cra_module	 =	THIS_MODULE,
	}
};

static int __init rmd160_mod_init(void)
{
	return crypto_register_shash(&alg);
}

static void __exit rmd160_mod_fini(void)
{
	crypto_unregister_shash(&alg);
}

module_init(rmd160_mod_init);
module_exit(rmd160_mod_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Adrian-Ken Rueegsegger <ken@codelabs.ch>");
MODULE_DESCRIPTION("RIPEMD-160 Message Digest");
MODULE_ALIAS_CRYPTO("rmd160");
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