From: Nick Terrell <nickrterrell@gmail.com>
To: Borislav Petkov <bp@alien8.de>, Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org, Chris Mason <clm@fb.com>,
linux-kbuild@vger.kernel.org, x86@kernel.org,
gregkh@linuxfoundation.org, Petr Malat <oss@malat.biz>,
Kees Cook <keescook@chromium.org>,
Kernel Team <Kernel-team@fb.com>,
Nick Terrell <nickrterrell@gmail.com>,
Adam Borowski <kilobyte@angband.pl>,
Patrick Williams <patrickw3@fb.com>,
rmikey@fb.com, mingo@kernel.org,
Patrick Williams <patrick@stwcx.xyz>,
Sedat Dilek <sedat.dilek@gmail.com>,
Norbert Lange <nolange79@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Alex Xu <alex_y_xu@yahoo.ca>,
Masahiro Yamada <masahiroy@kernel.org>,
Nick Terrell <terrelln@fb.com>
Subject: [PATCH v10 1/8] lib: prepare zstd for preboot environment
Date: Thu, 30 Jul 2020 12:08:34 -0700 [thread overview]
Message-ID: <20200730190841.2071656-2-nickrterrell@gmail.com> (raw)
In-Reply-To: <20200730190841.2071656-1-nickrterrell@gmail.com>
From: Nick Terrell <terrelln@fb.com>
* Remove a double definition of the CHECK_F macro when the zstd
library is amalgamated.
* Switch ZSTD_copy8() to __builtin_memcpy(), because in the preboot
environment on x86 gcc can't inline `memcpy()` otherwise.
* Limit the gcc hack in ZSTD_wildcopy() to the broken gcc version. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81388.
These changes are necessary to get the build to work in the preboot
environment, and to get reasonable performance. ZSTD_copy8() and
ZSTD_wildcopy() are in the core of the zstd hot loop. So outlining
these calls to memcpy(), and having an extra branch are very
detrimental to performance.
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Signed-off-by: Nick Terrell <terrelln@fb.com>
---
lib/zstd/fse_decompress.c | 9 +--------
lib/zstd/zstd_internal.h | 14 ++++++++++++--
2 files changed, 13 insertions(+), 10 deletions(-)
diff --git a/lib/zstd/fse_decompress.c b/lib/zstd/fse_decompress.c
index a84300e5a013..0b353530fb3f 100644
--- a/lib/zstd/fse_decompress.c
+++ b/lib/zstd/fse_decompress.c
@@ -47,6 +47,7 @@
****************************************************************/
#include "bitstream.h"
#include "fse.h"
+#include "zstd_internal.h"
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/string.h> /* memcpy, memset */
@@ -60,14 +61,6 @@
enum { FSE_static_assert = 1 / (int)(!!(c)) }; \
} /* use only *after* variable declarations */
-/* check and forward error code */
-#define CHECK_F(f) \
- { \
- size_t const e = f; \
- if (FSE_isError(e)) \
- return e; \
- }
-
/* **************************************************************
* Templates
****************************************************************/
diff --git a/lib/zstd/zstd_internal.h b/lib/zstd/zstd_internal.h
index 1a79fab9e13a..dac753397f86 100644
--- a/lib/zstd/zstd_internal.h
+++ b/lib/zstd/zstd_internal.h
@@ -127,7 +127,14 @@ static const U32 OF_defaultNormLog = OF_DEFAULTNORMLOG;
* Shared functions to include for inlining
*********************************************/
ZSTD_STATIC void ZSTD_copy8(void *dst, const void *src) {
- memcpy(dst, src, 8);
+ /*
+ * zstd relies heavily on gcc being able to analyze and inline this
+ * memcpy() call, since it is called in a tight loop. Preboot mode
+ * is compiled in freestanding mode, which stops gcc from analyzing
+ * memcpy(). Use __builtin_memcpy() to tell gcc to analyze this as a
+ * regular memcpy().
+ */
+ __builtin_memcpy(dst, src, 8);
}
/*! ZSTD_wildcopy() :
* custom version of memcpy(), can copy up to 7 bytes too many (8 bytes if length==0) */
@@ -137,13 +144,16 @@ ZSTD_STATIC void ZSTD_wildcopy(void *dst, const void *src, ptrdiff_t length)
const BYTE* ip = (const BYTE*)src;
BYTE* op = (BYTE*)dst;
BYTE* const oend = op + length;
- /* Work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81388.
+#if defined(GCC_VERSION) && GCC_VERSION >= 70000 && GCC_VERSION < 70200
+ /*
+ * Work around https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81388.
* Avoid the bad case where the loop only runs once by handling the
* special case separately. This doesn't trigger the bug because it
* doesn't involve pointer/integer overflow.
*/
if (length <= 8)
return ZSTD_copy8(dst, src);
+#endif
do {
ZSTD_copy8(op, ip);
op += 8;
--
2.27.0
next prev parent reply other threads:[~2020-07-30 19:11 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-30 19:08 [GIT PULL][PATCH v10 0/8] Add support for ZSTD-compressed kernel and initramfs Nick Terrell
2020-07-30 19:08 ` Nick Terrell [this message]
2020-07-30 19:08 ` [PATCH v10 2/8] lib: add zstd support to decompress Nick Terrell
2020-07-30 19:08 ` [PATCH v10 3/8] init: add support for zstd compressed kernel Nick Terrell
2020-07-30 19:08 ` [PATCH v10 4/8] usr: add support for zstd compressed initramfs Nick Terrell
2020-08-04 6:52 ` Geert Uytterhoeven
2020-08-04 7:25 ` Sedat Dilek
2020-08-04 9:19 ` Adam Borowski
2020-07-30 19:08 ` [PATCH v10 5/8] x86: bump ZO_z_extra_bytes margin for zstd Nick Terrell
2020-07-30 19:08 ` [PATCH v10 6/8] x86: Add support for ZSTD compressed kernel Nick Terrell
2020-07-30 19:08 ` [PATCH v10 7/8] .gitignore: add ZSTD-compressed files Nick Terrell
2020-07-31 9:50 ` Ingo Molnar
2020-07-31 17:17 ` Nick Terrell
2020-07-30 19:08 ` [PATCH v10 8/8] Documentation: dontdiff: Add zstd compressed files Nick Terrell
2020-07-31 9:47 ` [GIT PULL][PATCH v10 0/8] Add support for ZSTD-compressed kernel and initramfs Sedat Dilek
2020-07-31 14:36 ` Sedat Dilek
2020-08-04 6:47 ` Sedat Dilek
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