[PATCH v2 1/3] decompressors: Update xz to include ARM64 BCJ decoder

[Jules Maselbas <jmaselbas@zdiv.net>]

Update lib/xz/xz_dec_bcj.c and lib/xz/xz_private.h files from xz-embedded [1],
which include spelling fixes and the new ARM64 BCJ decoder which was recently
introduced into .xz file format version 1.1.0 (2022-12-11) [2].

[1] https://git.tukaani.org/?p=xz-embedded.git
[2] https://tukaani.org/xz/xz-file-format-1.1.0.txt

Signed-off-by: Jules Maselbas <jmaselbas@zdiv.net>
---
v2:
 - only select ARM64 BCJ on aarch64 (previously was ARM and ARM64)
 - fix condition in xz_private.h to enable BCJ decoders when only ARM64 BCJ
   decoder is selected (https://www.mail-archive.com/xz-devel@tukaani.org/msg00638.html)
---
 lib/Kconfig           |  4 ++++
 lib/decompress_unxz.c |  6 ++++-
 lib/xz/xz_dec_bcj.c   | 54 ++++++++++++++++++++++++++++++++++++++++---
 lib/xz/xz_private.h   |  5 +++-
 4 files changed, 64 insertions(+), 5 deletions(-)

diff --git a/lib/Kconfig b/lib/Kconfig
index 758197b608..9291e5a8ff 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -42,6 +42,7 @@ config XZ_DECOMPRESS
 	select XZ_DEC_ARM
 	select XZ_DEC_ARMTHUMB
 	select XZ_DEC_SPARC
+	select XZ_DEC_ARM64
 
 config XZ_DEC_X86
         bool
@@ -61,6 +62,9 @@ config XZ_DEC_ARMTHUMB
 config XZ_DEC_SPARC
         bool
 
+config XZ_DEC_ARM64
+	bool "ARM64 BCJ filter decoder"
+
 config REED_SOLOMON
 	bool
 
diff --git a/lib/decompress_unxz.c b/lib/decompress_unxz.c
index a7e2d331ab..132ab4a239 100644
--- a/lib/decompress_unxz.c
+++ b/lib/decompress_unxz.c
@@ -131,7 +131,11 @@
 #	define XZ_DEC_POWERPC
 #endif
 #ifdef CONFIG_ARM
-#	define XZ_DEC_ARM
+#	ifdef CONFIG_CPU_64
+#		define XZ_DEC_ARM64
+#	else
+#		define XZ_DEC_ARM
+#	endif
 #endif
 #ifdef CONFIG_IA64
 #	define XZ_DEC_IA64
diff --git a/lib/xz/xz_dec_bcj.c b/lib/xz/xz_dec_bcj.c
index d268adbc65..d40fae3416 100644
--- a/lib/xz/xz_dec_bcj.c
+++ b/lib/xz/xz_dec_bcj.c
@@ -2,7 +2,7 @@
  * Branch/Call/Jump (BCJ) filter decoders
  *
  * Authors: Lasse Collin <lasse.collin@tukaani.org>
- *          Igor Pavlov <http://7-zip.org/>
+ *          Igor Pavlov <https://7-zip.org/>
  *
  * This file has been put into the public domain.
  * You can do whatever you want with this file.
@@ -24,7 +24,8 @@ struct xz_dec_bcj {
 		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 */
+		BCJ_SPARC = 9,      /* Big or little endian */
+		BCJ_ARM64 = 10      /* AArch64 */
 	} type;
 
 	/*
@@ -334,6 +335,45 @@ static size_t bcj_sparc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
 }
 #endif
 
+#ifdef XZ_DEC_ARM64
+static size_t bcj_arm64(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
+{
+	size_t i;
+	uint32_t instr;
+	uint32_t addr;
+
+	for (i = 0; i + 4 <= size; i += 4) {
+		instr = get_unaligned_le32(buf + i);
+
+		if ((instr >> 26) == 0x25) {
+			/* BL instruction */
+			addr = instr - ((s->pos + (uint32_t)i) >> 2);
+			instr = 0x94000000 | (addr & 0x03FFFFFF);
+			put_unaligned_le32(instr, buf + i);
+
+		} else if ((instr & 0x9F000000) == 0x90000000) {
+			/* ADRP instruction */
+			addr = ((instr >> 29) & 3) | ((instr >> 3) & 0x1FFFFC);
+
+			/* Only convert values in the range +/-512 MiB. */
+			if ((addr + 0x020000) & 0x1C0000)
+				continue;
+
+			addr -= (s->pos + (uint32_t)i) >> 12;
+
+			instr &= 0x9000001F;
+			instr |= (addr & 3) << 29;
+			instr |= (addr & 0x03FFFC) << 3;
+			instr |= (0U - (addr & 0x020000)) & 0xE00000;
+
+			put_unaligned_le32(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.
@@ -380,6 +420,11 @@ static void bcj_apply(struct xz_dec_bcj *s,
 	case BCJ_SPARC:
 		filtered = bcj_sparc(s, buf, size);
 		break;
+#endif
+#ifdef XZ_DEC_ARM64
+	case BCJ_ARM64:
+		filtered = bcj_arm64(s, buf, size);
+		break;
 #endif
 	default:
 		/* Never reached but silence compiler warnings. */
@@ -422,7 +467,7 @@ XZ_EXTERN enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
 
 	/*
 	 * Flush pending already filtered data to the output buffer. Return
-	 * immediatelly if we couldn't flush everything, or if the next
+	 * immediately 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) {
@@ -553,6 +598,9 @@ XZ_EXTERN enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
 #endif
 #ifdef XZ_DEC_SPARC
 	case BCJ_SPARC:
+#endif
+#ifdef XZ_DEC_ARM64
+	case BCJ_ARM64:
 #endif
 		break;
 
diff --git a/lib/xz/xz_private.h b/lib/xz/xz_private.h
index 85f79635f0..b14a262c92 100644
--- a/lib/xz/xz_private.h
+++ b/lib/xz/xz_private.h
@@ -37,6 +37,9 @@
 #		ifdef CONFIG_XZ_DEC_SPARC
 #			define XZ_DEC_SPARC
 #		endif
+#		ifdef CONFIG_XZ_DEC_ARM64
+#			define XZ_DEC_ARM64
+#		endif
 #		define memeq(a, b, size) (memcmp(a, b, size) == 0)
 #		define memzero(buf, size) memset(buf, 0, size)
 #		define FREE free
@@ -98,7 +101,7 @@
 #ifndef XZ_DEC_BCJ
 #	if defined(XZ_DEC_X86) || defined(XZ_DEC_POWERPC) \
 			|| defined(XZ_DEC_IA64) || defined(XZ_DEC_ARM) \
-			|| defined(XZ_DEC_ARM) || defined(XZ_DEC_ARMTHUMB) \
+			|| defined(XZ_DEC_ARM64) || defined(XZ_DEC_ARMTHUMB) \
 			|| defined(XZ_DEC_SPARC)
 #		define XZ_DEC_BCJ
 #	endif
-- 
2.42.0