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authorNick Terrell <terrelln@fb.com>2020-07-30 22:08:39 +0300
committerIngo Molnar <mingo@kernel.org>2020-07-31 12:49:09 +0300
commitfb46d057db824693994b048d3a8c869892afaa3f (patch)
tree09d43e27af366f91b5845de5fa02ec58b52e5b55 /arch/x86/include/asm/boot.h
parent0fe4f4ef8cc8e15a8f29f08f4be6128395f125f6 (diff)
downloadlinux-fb46d057db824693994b048d3a8c869892afaa3f.tar.xz
x86: Add support for ZSTD compressed kernel
- Add support for zstd compressed kernel - Define __DISABLE_EXPORTS in Makefile - Remove __DISABLE_EXPORTS definition from kaslr.c - Bump the heap size for zstd. - Update the documentation. Integrates the ZSTD decompression code to the x86 pre-boot code. Zstandard requires slightly more memory during the kernel decompression on x86 (192 KB vs 64 KB), and the memory usage is independent of the window size. __DISABLE_EXPORTS is now defined in the Makefile, which covers both the existing use in kaslr.c, and the use needed by the zstd decompressor in misc.c. This patch has been boot tested with both a zstd and gzip compressed kernel on i386 and x86_64 using buildroot and QEMU. Additionally, this has been tested in production on x86_64 devices. We saw a 2 second boot time reduction by switching kernel compression from xz to zstd. Signed-off-by: Nick Terrell <terrelln@fb.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Sedat Dilek <sedat.dilek@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20200730190841.2071656-7-nickrterrell@gmail.com
Diffstat (limited to 'arch/x86/include/asm/boot.h')
-rw-r--r--arch/x86/include/asm/boot.h11
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86/include/asm/boot.h b/arch/x86/include/asm/boot.h
index 680c320363db..9191280d9ea3 100644
--- a/arch/x86/include/asm/boot.h
+++ b/arch/x86/include/asm/boot.h
@@ -24,9 +24,16 @@
# error "Invalid value for CONFIG_PHYSICAL_ALIGN"
#endif
-#ifdef CONFIG_KERNEL_BZIP2
+#if defined(CONFIG_KERNEL_BZIP2)
# define BOOT_HEAP_SIZE 0x400000
-#else /* !CONFIG_KERNEL_BZIP2 */
+#elif defined(CONFIG_KERNEL_ZSTD)
+/*
+ * Zstd needs to allocate the ZSTD_DCtx in order to decompress the kernel.
+ * The ZSTD_DCtx is ~160KB, so set the heap size to 192KB because it is a
+ * round number and to allow some slack.
+ */
+# define BOOT_HEAP_SIZE 0x30000
+#else
# define BOOT_HEAP_SIZE 0x10000
#endif