MIPS: Add support for ZSTD-compressed kernels

Add support for self-extracting kernels with a ZSTD compression.

Tested on a kernel for the GCW-Zero, it allows to reduce the size of the
kernel file from 4.1 MiB with gzip to 3.5 MiB with ZSTD, and boots just
as fast.

Compressed kernels are now also compiled with -D__DISABLE_EXPORTS in
order to disable the EXPORT_SYMBOL() macros inside of
lib/zstd/decompress.c.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 99220e7..a35dd02 100644 (file)
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1860,6 +1860,7 @@ config SYS_SUPPORTS_ZBOOT
        select HAVE_KERNEL_LZMA
        select HAVE_KERNEL_LZO
        select HAVE_KERNEL_XZ
+       select HAVE_KERNEL_ZSTD
 
 config SYS_SUPPORTS_ZBOOT_UART16550
        bool

diff --git a/arch/mips/boot/compressed/Makefile b/arch/mips/boot/compressed/Makefile
index 6e56cae..9a9ba77 100644 (file)
--- a/arch/mips/boot/compressed/Makefile
+++ b/arch/mips/boot/compressed/Makefile
@@ -22,7 +22,7 @@ KBUILD_CFLAGS := $(filter-out -pg, $(KBUILD_CFLAGS))
 
 KBUILD_CFLAGS := $(filter-out -fstack-protector, $(KBUILD_CFLAGS))
 
-KBUILD_CFLAGS := $(KBUILD_CFLAGS) -D__KERNEL__ \
+KBUILD_CFLAGS := $(KBUILD_CFLAGS) -D__KERNEL__ -D__DISABLE_EXPORTS \
        -DBOOT_HEAP_SIZE=$(BOOT_HEAP_SIZE) -D"VMLINUX_LOAD_ADDRESS_ULL=$(VMLINUX_LOAD_ADDRESS)ull"
 
 KBUILD_AFLAGS := $(KBUILD_AFLAGS) -D__ASSEMBLY__ \
@@ -70,6 +70,7 @@ tool_$(CONFIG_KERNEL_LZ4)     = lz4
 tool_$(CONFIG_KERNEL_LZMA)    = lzma
 tool_$(CONFIG_KERNEL_LZO)     = lzo
 tool_$(CONFIG_KERNEL_XZ)      = xzkern
+tool_$(CONFIG_KERNEL_ZSTD)    = zstd22
 
 targets += vmlinux.bin.z
 $(obj)/vmlinux.bin.z: $(obj)/vmlinux.bin FORCE

diff --git a/arch/mips/boot/compressed/decompress.c b/arch/mips/boot/compressed/decompress.c
index 88f5d63..c61c641 100644 (file)
--- a/arch/mips/boot/compressed/decompress.c
+++ b/arch/mips/boot/compressed/decompress.c
@@ -72,6 +72,10 @@ void error(char *x)
 #include "../../../../lib/decompress_unxz.c"
 #endif
 
+#ifdef CONFIG_KERNEL_ZSTD
+#include "../../../../lib/decompress_unzstd.c"
+#endif
+
 const unsigned long __stack_chk_guard = 0x000a0dff;
 
 void __stack_chk_fail(void)

diff --git a/arch/mips/boot/compressed/string.c b/arch/mips/boot/compressed/string.c
index 43beecc..0b593b7 100644 (file)
--- a/arch/mips/boot/compressed/string.c
+++ b/arch/mips/boot/compressed/string.c
@@ -5,6 +5,7 @@
  * Very small subset of simple string routines
  */
 
+#include <linux/compiler_attributes.h>
 #include <linux/types.h>
 
 void *memcpy(void *dest, const void *src, size_t n)
@@ -27,3 +28,19 @@ void *memset(void *s, int c, size_t n)
                ss[i] = c;
        return s;
 }
+
+void * __weak memmove(void *dest, const void *src, size_t n)
+{
+       unsigned int i;
+       const char *s = src;
+       char *d = dest;
+
+       if ((uintptr_t)dest < (uintptr_t)src) {
+               for (i = 0; i < n; i++)
+                       d[i] = s[i];
+       } else {
+               for (i = n; i > 0; i--)
+                       d[i - 1] = s[i - 1];
+       }
+       return dest;
+}