1 files changed, 561 insertions, 0 deletions

diff --git a/lib/xz/xz_dec_bcj.c b/lib/xz/xz_dec_bcj.c
new file mode 100644
index 000000000000..e51e2558ca9d
--- /dev/null
+++ b/lib/xz/xz_dec_bcj.c
@@ -0,0 +1,561 @@
+/*
+ * Branch/Call/Jump (BCJ) filter decoders
+ *
+ * Authors: Lasse Collin <lasse.collin@tukaani.org>
+ *          Igor Pavlov <http://7-zip.org/>
+ *
+ * This file has been put into the public domain.
+ * You can do whatever you want with this file.
+ */
+
+#include "xz_private.h"
+
+/*
+ * The rest of the file is inside this ifdef. It makes things a little more
+ * convenient when building without support for any BCJ filters.
+ */
+#ifdef XZ_DEC_BCJ
+
+struct xz_dec_bcj {
+        /* Type of the BCJ filter being used */
+        enum {
+                BCJ_X86 = 4,        /* x86 or x86-64 */
+                BCJ_POWERPC = 5,    /* Big endian only */
+                BCJ_IA64 = 6,       /* Big or little endian */
+                BCJ_ARM = 7,        /* Little endian only */
+                BCJ_ARMTHUMB = 8,   /* Little endian only */
+                BCJ_SPARC = 9       /* Big or little endian */
+        } type;
+
+        /*
+         * Return value of the next filter in the chain. We need to preserve
+         * this information across calls, because we must not call the next
+         * filter anymore once it has returned XZ_STREAM_END.
+         */
+        enum xz_ret ret;
+
+        /* True if we are operating in single-call mode. */
+        bool single_call;
+
+        /*
+         * Absolute position relative to the beginning of the uncompressed
+         * data (in a single .xz Block). We care only about the lowest 32
+         * bits so this doesn't need to be uint64_t even with big files.
+         */
+        uint32_t pos;
+
+        /* x86 filter state */
+        uint32_t x86_prev_mask;
+
+        /* Temporary space to hold the variables from struct xz_buf */
+        uint8_t *out;
+        size_t out_pos;
+        size_t out_size;
+
+        struct {
+                /* Amount of already filtered data in the beginning of buf */
+                size_t filtered;
+
+                /* Total amount of data currently stored in buf  */
+                size_t size;
+
+                /*
+                 * Buffer to hold a mix of filtered and unfiltered data. This
+                 * needs to be big enough to hold Alignment + 2 * Look-ahead:
+                 *
+                 * Type         Alignment   Look-ahead
+                 * x86              1           4
+                 * PowerPC          4           0
+                 * IA-64           16           0
+                 * ARM              4           0
+                 * ARM-Thumb        2           2
+                 * SPARC            4           0
+                 */
+                uint8_t buf[16];
+        } temp;
+};
+
+#ifdef XZ_DEC_X86
+/*
+ * This is used to test the most significant byte of a memory address
+ * in an x86 instruction.
+ */
+static inline int bcj_x86_test_msbyte(uint8_t b)
+{
+        return b == 0x00 || b == 0xFF;
+}
+
+static size_t bcj_x86(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        static const bool mask_to_allowed_status[8]
+                = { true, true, true, false, true, false, false, false };
+
+        static const uint8_t mask_to_bit_num[8] = { 0, 1, 2, 2, 3, 3, 3, 3 };
+
+        size_t i;
+        size_t prev_pos = (size_t)-1;
+        uint32_t prev_mask = s->x86_prev_mask;
+        uint32_t src;
+        uint32_t dest;
+        uint32_t j;
+        uint8_t b;
+
+        if (size <= 4)
+                return 0;
+
+        size -= 4;
+        for (i = 0; i < size; ++i) {
+                if ((buf[i] & 0xFE) != 0xE8)
+                        continue;
+
+                prev_pos = i - prev_pos;
+                if (prev_pos > 3) {
+                        prev_mask = 0;
+                } else {
+                        prev_mask = (prev_mask << (prev_pos - 1)) & 7;
+                        if (prev_mask != 0) {
+                                b = buf[i + 4 - mask_to_bit_num[prev_mask]];
+                                if (!mask_to_allowed_status[prev_mask]
+                                                || bcj_x86_test_msbyte(b)) {
+                                        prev_pos = i;
+                                        prev_mask = (prev_mask << 1) | 1;
+                                        continue;
+                                }
+                        }
+                }
+
+                prev_pos = i;
+
+                if (bcj_x86_test_msbyte(buf[i + 4])) {
+                        src = get_unaligned_le32(buf + i + 1);
+                        while (true) {
+                                dest = src - (s->pos + (uint32_t)i + 5);
+                                if (prev_mask == 0)
+                                        break;
+
+                                j = mask_to_bit_num[prev_mask] * 8;
+                                b = (uint8_t)(dest >> (24 - j));
+                                if (!bcj_x86_test_msbyte(b))
+                                        break;
+
+                                src = dest ^ (((uint32_t)1 << (32 - j)) - 1);
+                        }
+
+                        dest &= 0x01FFFFFF;
+                        dest |= (uint32_t)0 - (dest & 0x01000000);
+                        put_unaligned_le32(dest, buf + i + 1);
+                        i += 4;
+                } else {
+                        prev_mask = (prev_mask << 1) | 1;
+                }
+        }
+
+        prev_pos = i - prev_pos;
+        s->x86_prev_mask = prev_pos > 3 ? 0 : prev_mask << (prev_pos - 1);
+        return i;
+}
+#endif
+
+#ifdef XZ_DEC_POWERPC
+static size_t bcj_powerpc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        size_t i;
+        uint32_t instr;
+
+        for (i = 0; i + 4 <= size; i += 4) {
+                instr = get_unaligned_be32(buf + i);
+                if ((instr & 0xFC000003) == 0x48000001) {
+                        instr &= 0x03FFFFFC;
+                        instr -= s->pos + (uint32_t)i;
+                        instr &= 0x03FFFFFC;
+                        instr |= 0x48000001;
+                        put_unaligned_be32(instr, buf + i);
+                }
+        }
+
+        return i;
+}
+#endif
+
+#ifdef XZ_DEC_IA64
+static size_t bcj_ia64(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        static const uint8_t branch_table[32] = {
+                0, 0, 0, 0, 0, 0, 0, 0,
+                0, 0, 0, 0, 0, 0, 0, 0,
+                4, 4, 6, 6, 0, 0, 7, 7,
+                4, 4, 0, 0, 4, 4, 0, 0
+        };
+
+        /*
+         * The local variables take a little bit stack space, but it's less
+         * than what LZMA2 decoder takes, so it doesn't make sense to reduce
+         * stack usage here without doing that for the LZMA2 decoder too.
+         */
+
+        /* Loop counters */
+        size_t i;
+        size_t j;
+
+        /* Instruction slot (0, 1, or 2) in the 128-bit instruction word */
+        uint32_t slot;
+
+        /* Bitwise offset of the instruction indicated by slot */
+        uint32_t bit_pos;
+
+        /* bit_pos split into byte and bit parts */
+        uint32_t byte_pos;
+        uint32_t bit_res;
+
+        /* Address part of an instruction */
+        uint32_t addr;
+
+        /* Mask used to detect which instructions to convert */
+        uint32_t mask;
+
+        /* 41-bit instruction stored somewhere in the lowest 48 bits */
+        uint64_t instr;
+
+        /* Instruction normalized with bit_res for easier manipulation */
+        uint64_t norm;
+
+        for (i = 0; i + 16 <= size; i += 16) {
+                mask = branch_table[buf[i] & 0x1F];
+                for (slot = 0, bit_pos = 5; slot < 3; ++slot, bit_pos += 41) {
+                        if (((mask >> slot) & 1) == 0)
+                                continue;
+
+                        byte_pos = bit_pos >> 3;
+                        bit_res = bit_pos & 7;
+                        instr = 0;
+                        for (j = 0; j < 6; ++j)
+                                instr |= (uint64_t)(buf[i + j + byte_pos])
+                                                << (8 * j);
+
+                        norm = instr >> bit_res;
+
+                        if (((norm >> 37) & 0x0F) == 0x05
+                                        && ((norm >> 9) & 0x07) == 0) {
+                                addr = (norm >> 13) & 0x0FFFFF;
+                                addr |= ((uint32_t)(norm >> 36) & 1) << 20;
+                                addr <<= 4;
+                                addr -= s->pos + (uint32_t)i;
+                                addr >>= 4;
+
+                                norm &= ~((uint64_t)0x8FFFFF << 13);
+                                norm |= (uint64_t)(addr & 0x0FFFFF) << 13;
+                                norm |= (uint64_t)(addr & 0x100000)
+                                                << (36 - 20);
+
+                                instr &= (1 << bit_res) - 1;
+                                instr |= norm << bit_res;
+
+                                for (j = 0; j < 6; j++)
+                                        buf[i + j + byte_pos]
+                                                = (uint8_t)(instr >> (8 * j));
+                        }
+                }
+        }
+
+        return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARM
+static size_t bcj_arm(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        size_t i;
+        uint32_t addr;
+
+        for (i = 0; i + 4 <= size; i += 4) {
+                if (buf[i + 3] == 0xEB) {
+                        addr = (uint32_t)buf[i] | ((uint32_t)buf[i + 1] << 8)
+                                        | ((uint32_t)buf[i + 2] << 16);
+                        addr <<= 2;
+                        addr -= s->pos + (uint32_t)i + 8;
+                        addr >>= 2;
+                        buf[i] = (uint8_t)addr;
+                        buf[i + 1] = (uint8_t)(addr >> 8);
+                        buf[i + 2] = (uint8_t)(addr >> 16);
+                }
+        }
+
+        return i;
+}
+#endif
+
+#ifdef XZ_DEC_ARMTHUMB
+static size_t bcj_armthumb(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        size_t i;
+        uint32_t addr;
+
+        for (i = 0; i + 4 <= size; i += 2) {
+                if ((buf[i + 1] & 0xF8) == 0xF0
+                                && (buf[i + 3] & 0xF8) == 0xF8) {
+                        addr = (((uint32_t)buf[i + 1] & 0x07) << 19)
+                                        | ((uint32_t)buf[i] << 11)
+                                        | (((uint32_t)buf[i + 3] & 0x07) << 8)
+                                        | (uint32_t)buf[i + 2];
+                        addr <<= 1;
+                        addr -= s->pos + (uint32_t)i + 4;
+                        addr >>= 1;
+                        buf[i + 1] = (uint8_t)(0xF0 | ((addr >> 19) & 0x07));
+                        buf[i] = (uint8_t)(addr >> 11);
+                        buf[i + 3] = (uint8_t)(0xF8 | ((addr >> 8) & 0x07));
+                        buf[i + 2] = (uint8_t)addr;
+                        i += 2;
+                }
+        }
+
+        return i;
+}
+#endif
+
+#ifdef XZ_DEC_SPARC
+static size_t bcj_sparc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+        size_t i;
+        uint32_t instr;
+
+        for (i = 0; i + 4 <= size; i += 4) {
+                instr = get_unaligned_be32(buf + i);
+                if ((instr >> 22) == 0x100 || (instr >> 22) == 0x1FF) {
+                        instr <<= 2;
+                        instr -= s->pos + (uint32_t)i;
+                        instr >>= 2;
+                        instr = ((uint32_t)0x40000000 - (instr & 0x400000))
+                                        | 0x40000000 | (instr & 0x3FFFFF);
+                        put_unaligned_be32(instr, buf + i);
+                }
+        }
+
+        return i;
+}
+#endif
+
+/*
+ * Apply the selected BCJ filter. Update *pos and s->pos to match the amount
+ * of data that got filtered.
+ *
+ * NOTE: This is implemented as a switch statement to avoid using function
+ * pointers, which could be problematic in the kernel boot code, which must
+ * avoid pointers to static data (at least on x86).
+ */
+static void bcj_apply(struct xz_dec_bcj *s,
+                      uint8_t *buf, size_t *pos, size_t size)
+{
+        size_t filtered;
+
+        buf += *pos;
+        size -= *pos;
+
+        switch (s->type) {
+#ifdef XZ_DEC_X86
+        case BCJ_X86:
+                filtered = bcj_x86(s, buf, size);
+                break;
+#endif
+#ifdef XZ_DEC_POWERPC
+        case BCJ_POWERPC:
+                filtered = bcj_powerpc(s, buf, size);
+                break;
+#endif
+#ifdef XZ_DEC_IA64
+        case BCJ_IA64:
+                filtered = bcj_ia64(s, buf, size);
+                break;
+#endif
+#ifdef XZ_DEC_ARM
+        case BCJ_ARM:
+                filtered = bcj_arm(s, buf, size);
+                break;
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+        case BCJ_ARMTHUMB:
+                filtered = bcj_armthumb(s, buf, size);
+                break;
+#endif
+#ifdef XZ_DEC_SPARC
+        case BCJ_SPARC:
+                filtered = bcj_sparc(s, buf, size);
+                break;
+#endif
+        default:
+                /* Never reached but silence compiler warnings. */
+                filtered = 0;
+                break;
+        }
+
+        *pos += filtered;
+        s->pos += filtered;
+}
+
+/*
+ * Flush pending filtered data from temp to the output buffer.
+ * Move the remaining mixture of possibly filtered and unfiltered
+ * data to the beginning of temp.
+ */
+static void bcj_flush(struct xz_dec_bcj *s, struct xz_buf *b)
+{
+        size_t copy_size;
+
+        copy_size = min_t(size_t, s->temp.filtered, b->out_size - b->out_pos);
+        memcpy(b->out + b->out_pos, s->temp.buf, copy_size);
+        b->out_pos += copy_size;
+
+        s->temp.filtered -= copy_size;
+        s->temp.size -= copy_size;
+        memmove(s->temp.buf, s->temp.buf + copy_size, s->temp.size);
+}
+
+/*
+ * The BCJ filter functions are primitive in sense that they process the
+ * data in chunks of 1-16 bytes. To hide this issue, this function does
+ * some buffering.
+ */
+XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
+                                     struct xz_dec_lzma2 *lzma2,
+                                     struct xz_buf *b)
+{
+        size_t out_start;
+
+        /*
+         * Flush pending already filtered data to the output buffer. Return
+         * immediatelly if we couldn't flush everything, or if the next
+         * filter in the chain had already returned XZ_STREAM_END.
+         */
+        if (s->temp.filtered > 0) {
+                bcj_flush(s, b);
+                if (s->temp.filtered > 0)
+                        return XZ_OK;
+
+                if (s->ret == XZ_STREAM_END)
+                        return XZ_STREAM_END;
+        }
+
+        /*
+         * If we have more output space than what is currently pending in
+         * temp, copy the unfiltered data from temp to the output buffer
+         * and try to fill the output buffer by decoding more data from the
+         * next filter in the chain. Apply the BCJ filter on the new data
+         * in the output buffer. If everything cannot be filtered, copy it
+         * to temp and rewind the output buffer position accordingly.
+         */
+        if (s->temp.size < b->out_size - b->out_pos) {
+                out_start = b->out_pos;
+                memcpy(b->out + b->out_pos, s->temp.buf, s->temp.size);
+                b->out_pos += s->temp.size;
+
+                s->ret = xz_dec_lzma2_run(lzma2, b);
+                if (s->ret != XZ_STREAM_END
+                                && (s->ret != XZ_OK || s->single_call))
+                        return s->ret;
+
+                bcj_apply(s, b->out, &out_start, b->out_pos);
+
+                /*
+                 * As an exception, if the next filter returned XZ_STREAM_END,
+                 * we can do that too, since the last few bytes that remain
+                 * unfiltered are meant to remain unfiltered.
+                 */
+                if (s->ret == XZ_STREAM_END)
+                        return XZ_STREAM_END;
+
+                s->temp.size = b->out_pos - out_start;
+                b->out_pos -= s->temp.size;
+                memcpy(s->temp.buf, b->out + b->out_pos, s->temp.size);
+        }
+
+        /*
+         * If we have unfiltered data in temp, try to fill by decoding more
+         * data from the next filter. Apply the BCJ filter on temp. Then we
+         * hopefully can fill the actual output buffer by copying filtered
+         * data from temp. A mix of filtered and unfiltered data may be left
+         * in temp; it will be taken care on the next call to this function.
+         */
+        if (s->temp.size > 0) {
+                /* Make b->out{,_pos,_size} temporarily point to s->temp. */
+                s->out = b->out;
+                s->out_pos = b->out_pos;
+                s->out_size = b->out_size;
+                b->out = s->temp.buf;
+                b->out_pos = s->temp.size;
+                b->out_size = sizeof(s->temp.buf);
+
+                s->ret = xz_dec_lzma2_run(lzma2, b);
+
+                s->temp.size = b->out_pos;
+                b->out = s->out;
+                b->out_pos = s->out_pos;
+                b->out_size = s->out_size;
+
+                if (s->ret != XZ_OK && s->ret != XZ_STREAM_END)
+                        return s->ret;
+
+                bcj_apply(s, s->temp.buf, &s->temp.filtered, s->temp.size);
+
+                /*
+                 * If the next filter returned XZ_STREAM_END, we mark that
+                 * everything is filtered, since the last unfiltered bytes
+                 * of the stream are meant to be left as is.
+                 */
+                if (s->ret == XZ_STREAM_END)
+                        s->temp.filtered = s->temp.size;
+
+                bcj_flush(s, b);
+                if (s->temp.filtered > 0)
+                        return XZ_OK;
+        }
+
+        return s->ret;
+}
+
+XZ_EXTERN struct xz_dec_bcj *xz_dec_bcj_create(bool single_call)
+{
+        struct xz_dec_bcj *s = kmalloc(sizeof(*s), GFP_KERNEL);
+        if (s != NULL)
+                s->single_call = single_call;
+
+        return s;
+}
+
+XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
+{
+        switch (id) {
+#ifdef XZ_DEC_X86
+        case BCJ_X86:
+#endif
+#ifdef XZ_DEC_POWERPC
+        case BCJ_POWERPC:
+#endif
+#ifdef XZ_DEC_IA64
+        case BCJ_IA64:
+#endif
+#ifdef XZ_DEC_ARM
+        case BCJ_ARM:
+#endif
+#ifdef XZ_DEC_ARMTHUMB
+        case BCJ_ARMTHUMB:
+#endif
+#ifdef XZ_DEC_SPARC
+        case BCJ_SPARC:
+#endif
+                break;
+
+        default:
+                /* Unsupported Filter ID */
+                return XZ_OPTIONS_ERROR;
+        }
+
+        s->type = id;
+        s->ret = XZ_OK;
+        s->pos = 0;
+        s->x86_prev_mask = 0;
+        s->temp.filtered = 0;
+        s->temp.size = 0;
+
+        return XZ_OK;
+}
+
+#endif