- 21 Apr, 2022 40 commits
-
-
Ammar Faizi authored
On i386, the 6th argument of syscall goes in %ebp. However, both Clang and GCC cannot use %ebp in the clobber list and in the "r" constraint without using -fomit-frame-pointer. To make it always available for any kind of compilation, the below workaround is implemented. 1) Push the 6-th argument. 2) Push %ebp. 3) Load the 6-th argument from 4(%esp) to %ebp. 4) Do the syscall (int $0x80). 5) Pop %ebp (restore the old value of %ebp). 6) Add %esp by 4 (undo the stack pointer). Cc: x86@kernel.org Cc: llvm@lists.linux.dev Link: https://lore.kernel.org/lkml/2e335ac54db44f1d8496583d97f9dab0@AcuMS.aculab.comSuggested-by:
David Laight <David.Laight@ACULAB.COM> Acked-by:
Willy Tarreau <w@1wt.eu> Signed-off-by:
Ammar Faizi <ammarfaizi2@gnuweeb.org> Signed-off-by:
Paul E. McKenney <paulmck@kernel.org>
-
Ammar Faizi authored
Building with clang yields the following error: ``` <inline asm>:3:1: error: _start changed binding to STB_GLOBAL .global _start ^ 1 error generated. ``` Make sure only specify one between `.global _start` and `.weak _start`. Remove `.global _start`. Cc: llvm@lists.linux.dev Reviewed-by:
Nick Desaulniers <ndesaulniers@google.com> Acked-by:
-
Ammar Faizi authored
Replace `asm` with `__asm__` to support compilation with -std flag. Using `asm` with -std flag makes GCC think `asm()` is a function call instead of an inline assembly. GCC doc says: For the C language, the `asm` keyword is a GNU extension. When writing C code that can be compiled with `-ansi` and the `-std` options that select C dialects without GNU extensions, use `__asm__` instead of `asm`. Link: https://gcc.gnu.org/onlinedocs/gcc/Basic-Asm.htmlReported-by:
Alviro Iskandar Setiawan <alviro.iskandar@gnuweeb.org> Acked-by:
-
Ammar Faizi authored
The old link no longer works, update it. Acked-by:
-
Willy Tarreau authored
When building with gcc at -O0 we're seeing link errors due to the "environ" variable being referenced by getenv(). The problem is that at -O0 gcc will not inline getenv() and will not drop the external reference. One solution would be to locally declare the variable as weak, but then it would appear in all programs even those not using it, and would be confusing to users of getenv() who would forget to set environ to envp. An alternate approach used in this patch consists in always inlining the outer part of getenv() that references this extern so that it's always dropped when not used. The biggest part of the function was now moved to a new function called _getenv() that's still not inlined by default. Reported-by:
-
Willy Tarreau authored
clang wants to use strlen() for __builtin_strlen() at -O0. We don't really care about -O0 but it at least ought to build, so let's make sure we don't choke on this, by dropping the optimizationn for constant strings in this case. Signed-off-by:
-
Willy Tarreau authored
The Makefile in tools/ is used to forward options to the makefiles in the various subdirs. Let's add nolibc there so that it becomes possible to make tools/nolibc_headers_standalone from the main tree to simply create a completely usable sysroot. Signed-off-by:
-
Willy Tarreau authored
This provides a target "headers_standalone" which installs the nolibc's arch-specific headers with "arch.h" taken from the current arch (or a concatenation of both i386 and x86_64 for arch=x86), then installs kernel headers. This creates a convenient sysroot which is directly usable by a bare-metal compiler to create any executable. Signed-off-by:
-
Willy Tarreau authored
- POLLIN etc were missing, so poll() could only be used with timeouts. - WNOHANG was not defined and is convenient to check if a child is still running Signed-off-by:
-
Willy Tarreau authored
This is essentially for completeness as it's not the most often used in regtests. Signed-off-by:
-
Willy Tarreau authored
We need these functions all the time, including when checking environment variables and parsing command-line arguments. These implementations were optimized to show optimal code size on a wide range of compilers (22 bytes return included for strcmp(), 33 for strncmp()). Signed-off-by:
-
Willy Tarreau authored
%p remains quite useful in test code, and the code path can easily be merged with the existing "%x" thus only adds ~50 bytes, thus let's add it. Signed-off-by:
-
Willy Tarreau authored
This implementation relies on an extern definition of the environ variable, that the caller must declare and initialize from envp. Signed-off-by:
-
Willy Tarreau authored
It's often convenient to support this, especially in test programs where a NULL may correspond to an allocation error or a non-existing value. Let's make printf("%s") support being passed a NULL. In this case it prints "(null)" like glibc's printf(). Signed-off-by: -
Willy Tarreau authored
libgcc uses it for certain divide functions, so it must be exported. Like for memset() we do that in its own section so that the linker can strip it when not needed. Signed-off-by:
-
Willy Tarreau authored
Now that a few basic include files are provided, some simple portable programs may build, which will save them from having to surround their includes with #ifndef NOLIBC. This patch mentions how to proceed, and enumerates the list of files that are covered. A comprehensive list of required include files is available here: https://en.cppreference.com/w/c/headerSigned-off-by:
-
Willy Tarreau authored
The time() syscall is used by a few simple applications, and is trivial to implement based on gettimeofday() that we already have. Let's create the file to ease porting and provide the function. It never returns any error, though it may segfault in case of invalid pointer, like other implementations relying on gettimeofday(). Signed-off-by:
-
Willy Tarreau authored
This function is normally found in signal.h, and providing the file eases porting of existing programs. Let's move it there. Signed-off-by:
-
Willy Tarreau authored
This call is trivial to implement based on select() to complete sleep() and msleep(), let's add it. Signed-off-by:
-
Willy Tarreau authored
These functions are normally provided by unistd.h. For ease of porting, let's create the file and move them there. Signed-off-by:
-
Willy Tarreau authored
This allows us to provide a minimal errno.h to ease porting applications that use it. Signed-off-by:
-
Willy Tarreau authored
"clang -Os" and "gcc -Ofast" without -ffreestanding may ignore memset() and memmove(), hoping to provide their builtin equivalents, and finally not find them. Thus we must export these functions for these rare cases. Note that as they're set in their own sections, they will be eliminated by the linker if not used. In addition, they do not prevent gcc from identifying them and replacing them with the shorter "rep movsb" or "rep stosb" when relevant. Signed-off-by:
-
Willy Tarreau authored
These ones are often used and commonly set by applications to fallback values. Let's fix them both to agree on PATH_MAX=4096 by default, as is already present in linux/limits.h. Signed-off-by:
-
Willy Tarreau authored
By doing so we can link together multiple C files that have been compiled with nolibc and which each have a _start symbol. Signed-off-by:
-
Willy Tarreau authored
Some functions like raise() and memcpy() are permanently exported because they're needed by libgcc on certain platforms. However most of the time they are not needed and needlessly take space. Let's move them to their own sub-section, called .text.nolibc_<function>. This allows ld to get rid of them if unused when passed --gc-sections. Signed-off-by:
-
Willy Tarreau authored
While these functions are often dangerous, forcing the user to work around their absence is often much worse. Let's provide small versions of each of them. The respective sizes in bytes on a few architectures are: strncat(): x86:0x33 mips:0x68 arm:0x3c strlcat(): x86:0x25 mips:0x4c arm:0x2c The two are quite different, and strncat() is even different from strncpy() in that it limits the amount of data it copies and will always terminate the output by one zero, while strlcat() will always limit the total output to the specified size and will put a zero if possible. Signed-off-by:
-
Willy Tarreau authored
These are minimal variants. strncpy() always fills the destination for <size> chars, while strlcpy() copies no more than <size> including the zero and returns the source's length. The respective sizes on various archs are: strncpy(): x86:0x1f mips:0x30 arm:0x20 strlcpy(): x86:0x17 mips:0x34 arm:0x1a Signed-off-by:
-
Willy Tarreau authored
The direction test inside the loop was not always completely optimized, resulting in a larger than necessary function. This change adds a direction variable that is set out of the loop. Now the function is down to 48 bytes on x86, 32 on ARM and 68 on mips. It's worth noting that other approaches were attempted (including relying on the up and down functions) but they were only slightly beneficial on x86 and cost more on others. Signed-off-by:
-
Willy Tarreau authored
Till now memcpy() relies on memmove(), but it's always included for libgcc, so we have a larger than needed function. Let's implement two unidirectional variants to copy from bottom to top and from top to bottom, and use the former for memcpy(). The variants are optimized to be compact, and at the same time the compiler is sometimes able to detect the loop and to replace it with a "rep movsb". The new function is 24 bytes instead of 52 on x86_64. Signed-off-by:
-
Willy Tarreau authored
These syscalls never fail so there is no need to extract and set errno for them. Signed-off-by:
-
Willy Tarreau authored
raise() doesn't set errno, so there's no point calling kill(), better call sys_kill(), which also reduces the function's size. Signed-off-by:
-
Willy Tarreau authored
The build of printf() on mips requires libgcc for functions __ashldi3 and __lshrdi3 due to 64-bit shifts when scanning the input number. These are not really needed in fact since we scan the number 4 bits at a time. Let's arrange the loop to perform two 32-bit shifts instead on 32-bit platforms. Signed-off-by:
-
Willy Tarreau authored
Let's pass a vararg to open() so that it remains compatible with existing code. The arg is only dereferenced when flags contain O_CREAT. The function is generally not inlined anymore, causing an extra call (total 16 extra bytes) but it's still optimized for constant propagation, limiting the excess to no more than 16 bytes in practice when open() is called without O_CREAT, and ~40 with O_CREAT, which remains reasonable. Signed-off-by:
-
Willy Tarreau authored
It doesn't contain the text for the error codes, but instead displays "errno=" followed by the errno value. Just like the regular errno, if a non-empty message is passed, it's placed followed with ": " on the output before the errno code. The message is emitted on stderr. Signed-off-by:
-
Willy Tarreau authored
These ones are found in some examples found in man pages and ease portability tests. Signed-off-by:
-
Willy Tarreau authored
This adds a minimal vfprintf() implementation as well as the commonly used fprintf() and printf() that rely on it. For now the function supports: - formats: %s, %c, %u, %d, %x - modifiers: %l and %ll - unknown chars are considered as modifiers and are ignored It is designed to remain minimalist, despite this printf() is 549 bytes on x86_64. It would be wise not to add too many formats. Signed-off-by:
-
Willy Tarreau authored
We'll use it to write substrings. It relies on a simpler _fwrite() that only takes one size. fputs() was also modified to rely on it. Signed-off-by:
-
Willy Tarreau authored
The standard puts() function always emits the trailing LF which makes it unconvenient for small string concatenation. fputs() ought to be used instead but it requires a FILE*. This adds 3 dummy FILE* values (stdin, stdout, stderr) which are in fact pointers to struct FILE of one byte. We reserve 3 pointer values for them, -3, -2 and -1, so that they are ordered, easing the tests and mapping to integer. >From this, fgetc(), fputc(), fgets() and fputs() were implemented, and the previous putchar() and getchar() now remap to these. The standard getc() and putc() macros were also implemented as pointing to these ones. There is absolutely no buffering, fgetc() and fgets() read one byte at a time, fputc() writes one byte at a time, and only fputs() which knows the string's length writes all of it at once. Signed-off-by:
-
Willy Tarreau authored
This only provides getchar(), putchar(), and puts(). Signed-off-by:
-
Willy Tarreau authored
This adds a pair of functions to emit hex values. Signed-off-by:
-
