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* [PATCH] arm: Add support for ZSTD compressed kernel
@ 2020-08-05 23:05 Norbert Lange
  2020-08-06  0:30 ` Russell King - ARM Linux admin
  0 siblings, 1 reply; 9+ messages in thread
From: Norbert Lange @ 2020-08-05 23:05 UTC (permalink / raw)
  To: Russell King, Arnd Bergmann
  Cc: linux-kernel, Petr Malat, Kees Cook, Adam Borowski, Sedat Dilek,
	Andrew Morton, Nick Terrell, Norbert Lange

* Add support for zstd compressed kernel
* Define __DISABLE_EXPORTS in Makefile
* Bump the heap size for zstd.

This replicates the steps taken for x86 support.

Only if ZSTD is selected, heap size for kernel decompression is
increased, this should guarantee no changes in code / sideeffects for
other compressors.

The patch is so far only tested with Qemu, and some 64MB size limit
exists (might be Qemu specific), but this seems not caused by
this patch (upstream 5.8 and GZIP exhibits similar problems).

Signed-off-by: Norbert Lange <nolange79@gmail.com>
---
 arch/arm/Kconfig                      | 1 +
 arch/arm/boot/compressed/Makefile     | 2 ++
 arch/arm/boot/compressed/decompress.c | 4 ++++
 arch/arm/boot/compressed/head.S       | 4 ++++
 4 files changed, 11 insertions(+)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 2ac74904a3ce..3e853cdc688d 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -93,6 +93,7 @@ config ARM
 	select HAVE_KERNEL_LZMA
 	select HAVE_KERNEL_LZO
 	select HAVE_KERNEL_XZ
+	select HAVE_KERNEL_ZSTD
 	select HAVE_KPROBES if !XIP_KERNEL && !CPU_ENDIAN_BE32 && !CPU_V7M
 	select HAVE_KRETPROBES if HAVE_KPROBES
 	select HAVE_MOD_ARCH_SPECIFIC
diff --git a/arch/arm/boot/compressed/Makefile b/arch/arm/boot/compressed/Makefile
index 00602a6fba04..61229e93ea4a 100644
--- a/arch/arm/boot/compressed/Makefile
+++ b/arch/arm/boot/compressed/Makefile
@@ -75,6 +75,7 @@ compress-$(CONFIG_KERNEL_LZO)  = lzo
 compress-$(CONFIG_KERNEL_LZMA) = lzma
 compress-$(CONFIG_KERNEL_XZ)   = xzkern
 compress-$(CONFIG_KERNEL_LZ4)  = lz4
+compress-$(CONFIG_KERNEL_ZSTD) = zstd22
 
 libfdt_objs := fdt_rw.o fdt_ro.o fdt_wip.o fdt.o
 
@@ -102,6 +103,7 @@ targets       := vmlinux vmlinux.lds piggy_data piggy.o \
 clean-files += piggy_data lib1funcs.S ashldi3.S bswapsdi2.S hyp-stub.S
 
 KBUILD_CFLAGS += -DDISABLE_BRANCH_PROFILING
+KBUILD_CFLAGS += -D__DISABLE_EXPORTS
 
 ifeq ($(CONFIG_FUNCTION_TRACER),y)
 ORIG_CFLAGS := $(KBUILD_CFLAGS)
diff --git a/arch/arm/boot/compressed/decompress.c b/arch/arm/boot/compressed/decompress.c
index aa075d8372ea..04f77491975a 100644
--- a/arch/arm/boot/compressed/decompress.c
+++ b/arch/arm/boot/compressed/decompress.c
@@ -56,6 +56,10 @@ extern char * strchrnul(const char *, int);
 #include "../../../../lib/decompress_unlz4.c"
 #endif
 
+#ifdef CONFIG_KERNEL_ZSTD
+#include "../../../../lib/decompress_unzstd.c"
+#endif
+
 int do_decompress(u8 *input, int len, u8 *output, void (*error)(char *x))
 {
 	return __decompress(input, len, NULL, NULL, output, 0, NULL, error);
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 434a16982e34..1af01bfe6638 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -614,7 +614,11 @@ not_relocated:	mov	r0, #0
  */
 		mov	r0, r4
 		mov	r1, sp			@ malloc space above stack
+#if defined(CONFIG_KERNEL_ZSTD)
+		add	r2, sp, #0x30000	@ Context needs ~160K
+#else
 		add	r2, sp, #0x10000	@ 64k max
+#endif
 		mov	r3, r7
 		bl	decompress_kernel
 
-- 
2.27.0


^ permalink raw reply related	[flat|nested] 9+ messages in thread
* [PATCH] arm: Add support for ZSTD compressed kernel
@ 2020-08-06 21:46 Peter Geis
  2020-08-06 22:22 ` Russell King - ARM Linux admin
  0 siblings, 1 reply; 9+ messages in thread
From: Peter Geis @ 2020-08-06 21:46 UTC (permalink / raw)
  To: nolange79
  Cc: linux-kernel, Petr Malat, Kees Cook, Adam Borowski, Sedat Dilek,
	Andrew Morton, Nick Terrell, Russell King, Arnd Bergmann,
	linux-tegra

Good Evening,

I had attempted to get this working as well, but have run into
difficulties with both my implementation and yours as well.
My implementation was almost the same as yours, with the exception of
also changing:
@@ -303,7 +305,7 @@ restart: adr r0, LC1

 #ifndef CONFIG_ZBOOT_ROM
  /* malloc space is above the relocated stack (64k max) */
- add r10, sp, #0x10000
+ add r10, sp, #0x30000
 #else
  /*
  * With ZBOOT_ROM the bss/stack is non relocatable,

On QEMU this implementation works fine.
However on bare metal tegra30, I get the following error:

Jumping to kernel at:4861 ms

C:0x80A000C0-0x8112BA40->0x8152C700-0x81C58080
Uncompressing Linux...

ZSTD-compressed dstSize is too small

 -- System halted

The only difference between the bare metal test and the qemu test is
the zImage with appended dtb is packaged in the android boot format
for the bare metal test.
Otherwise it's exactly the same file.

I had to modify the original zstd error message because it grouped
several errors together.
Here is my patch for that:

diff --git a/lib/decompress_unzstd.c b/lib/decompress_unzstd.c
index 062617bb0afe..89ac73e900ce 100644
--- a/lib/decompress_unzstd.c
+++ b/lib/decompress_unzstd.c
@@ -103,10 +103,14 @@ static int INIT handle_zstd_error(size_t ret,
void (*error)(char *x))
  error("Input is not in the ZSTD format (wrong magic bytes)");
  break;
  case ZSTD_error_dstSize_tooSmall:
+ error("ZSTD-compressed dstSize is too small");
+ break;
  case ZSTD_error_corruption_detected:
- case ZSTD_error_checksum_wrong:
  error("ZSTD-compressed data is corrupt");
  break;
+ case ZSTD_error_checksum_wrong:
+ error("ZSTD-compressed data checksum is wrong");
+ break;
  default:
  error("ZSTD-compressed data is probably corrupt");
  break;

Very Respectfully,
Peter Geis

^ permalink raw reply related	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2020-08-06 22:58 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2020-08-05 23:05 [PATCH] arm: Add support for ZSTD compressed kernel Norbert Lange
2020-08-06  0:30 ` Russell King - ARM Linux admin
2020-08-06  8:45   ` Norbert Lange
2020-08-06 10:11     ` Russell King - ARM Linux admin
2020-08-06 10:12       ` [PATCH 1/2] ARM: add TEXT_OFFSET to decompressor kexec image structure Russell King
2020-08-06 10:12       ` [PATCH 2/2] ARM: add malloc size to decompressor kexec size structure Russell King
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2020-08-06 21:46 [PATCH] arm: Add support for ZSTD compressed kernel Peter Geis
2020-08-06 22:22 ` Russell King - ARM Linux admin
2020-08-06 22:58   ` Peter Geis

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