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2022-04-20tools/nolibc/stdlib: implement abort()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc: also mention how to build by just setting the include pathWilly Tarreau
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/header Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/time: create time.h with time()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/signal: move raise() to signal.hWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/unistd: add usleep()Willy Tarreau
This call is trivial to implement based on select() to complete sleep() and msleep(), let's add it. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/unistd: extract msleep(), sleep(), tcsetpgrp() to unistd.hWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/errno: extract errno.h from sys.hWilly Tarreau
This allows us to provide a minimal errno.h to ease porting applications that use it. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: export memset() and memmove()Willy Tarreau
"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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: define PATH_MAX and MAXPATHLENWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/arch: mark the _start symbol as weakWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc: move exported functions to their own sectionWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: add tiny versions of strncat() and strlcat()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: add strncpy() and strlcpy()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: slightly simplify memmove()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: use unidirectional variants for memcpy()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/sys: make getpgrp(), getpid(), gettid() not set errnoWilly Tarreau
These syscalls never fail so there is no need to extract and set errno for them. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: make raise() use the lower level syscalls onlyWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: avoid a 64-bit shift in u64toh_r()Willy Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/sys: make open() take a vararg on the 3rd argumentWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add perror() to report the errno valueWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: define EXIT_SUCCESS and EXIT_FAILUREWilly Tarreau
These ones are found in some examples found in man pages and ease portability tests. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add a minimal [vf]printf() implementationWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add fwrite() to stdioWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add stdin/stdout/stderr and fget*/fput* functionsWilly Tarreau
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 <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdio: add a minimal set of stdio functionsWilly Tarreau
This only provides getchar(), putchar(), and puts(). Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: add utoh() and u64toh()Willy Tarreau
This adds a pair of functions to emit hex values. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: add i64toa() and u64toa()Willy Tarreau
These are 64-bit variants of the itoa() and utoa() functions. They also support reentrant ones, and use the same itoa_buffer. The functions are a bit larger than the previous ones in 32-bit mode (86 and 98 bytes on x86_64 and armv7 respectively), which is why we continue to provide them as separate functions. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: replace the ltoa() function with more efficient onesWilly Tarreau
The original ltoa() function and the reentrant one ltoa_r() present a number of drawbacks. The divide by 10 generates calls to external code from libgcc_s, and the number does not necessarily start at the beginning of the buffer. Let's rewrite these functions so that they do not involve a divide and only use loops on powers of 10, and implement both signed and unsigned variants, always starting from the buffer's first character. Instead of using a static buffer for each function, we're now using a common one. In order to avoid confusion with the ltoa() name, the new functions are called itoa_r() and utoa_r() to distinguish the signed and unsigned versions, and for convenience for their callers, these functions now reutrn the number of characters emitted. The ltoa_r() function is just an inline mapping to the signed one and which returns the buffer. The functions are quite small (86 bytes on x86_64, 68 on armv7) and do not depend anymore on external code. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: move ltoa() to stdlib.hWilly Tarreau
This function is not standard and performs the opposite of atol(). Let's move it with atol(). It's been split between a reentrant function and one using a static buffer. There's no more definition in nolibc.h anymore now. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: move makedev to types.h and make it a macroWilly Tarreau
The makedev() man page says it's supposed to be a macro and that some OSes have it with the other ones in sys/types.h so it now makes sense to move it to types.h as a macro. Let's also define major() and minor() that perform the reverse operation. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: make FD_SETSIZE configurableWilly Tarreau
The macro was hard-coded to 256 but it's common to see it redefined. Let's support this and make sure we always allocate enough entries for the cases where it wouldn't be multiple of 32. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: move the FD_* functions to macros in types.hWilly Tarreau
FD_SET, FD_CLR, FD_ISSET, FD_ZERO are often expected to be macros and not functions. In addition we already have a file dedicated to such macros and types used by syscalls, it's types.h, so let's move them there and turn them to macros. FD_CLR() and FD_ISSET() were missing, so they were added. FD_ZERO() now deals with its own loop so that it doesn't rely on memset() that sets one byte at a time. Cc: David Laight <David.Laight@aculab.com> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/ctype: add the missing is* functionsWilly Tarreau
There was only isdigit, this commit adds the other ones. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/ctype: split the is* functions to ctype.hWilly Tarreau
In fact there's only isdigit() for now. More should definitely be added. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/string: split the string functions into string.hWilly Tarreau
The string manipulation functions (mem*, str*) are now found in string.h. The file depends on almost nothing and will be usable from other includes if needed. Maybe more functions could be added. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/stdlib: extract the stdlib-specific functions to their own fileWilly Tarreau
The new file stdlib.h contains the definitions of functions that are usually found in stdlib.h. Many more could certainly be added. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/sys: split the syscall definitions into their own fileWilly Tarreau
The syscall definitions were moved to sys.h. They were arranged in a more easily maintainable order, whereby the sys_xxx() and xxx() functions were grouped together, which also enlights the occasional mappings such as wait relying on wait4(). Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/arch: split arch-specific code into individual filesWilly Tarreau
In order to ease maintenance, this splits the arch-specific code into one file per architecture. A common file "arch.h" is used to include the right file among arch-* based on the detected architecture. Projects which are already split per architecture could simply rename these files to $arch/arch.h and get rid of the common arch.h. For this reason, include guards were placed into each arch-specific file. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/types: split syscall-specific definitions into their own filesWilly Tarreau
The macros and type definitions used by a number of syscalls were moved to types.h where they will be easier to maintain. A few of them are arch-specific and must not be moved there (e.g. O_*, sys_stat_struct). A warning about them was placed at the top of the file. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-20tools/nolibc/std: move the standard type definitions to std.hWilly Tarreau
The ordering of includes and definitions for now is a bit of a mess, as for example asm/signal.h is included after int definitions, but plenty of structures are defined later as they rely on other includes. Let's move the standard type definitions to a dedicated file that is included first. We also move NULL there. This way all other includes are aware of it, and we can bring asm/signal.h back to the top of the file. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-11tools/nolibc: guard the main file against multiple inclusionWilly Tarreau
Including nolibc.h multiple times results in build errors due to multiple definitions. Let's add a guard against multiple inclusions. Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2022-04-11tools/nolibc: use pselect6 on RISCVWilly Tarreau
This arch doesn't provide the old-style select() syscall, we have to use pselect6(). Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: Implement gettid()Mark Brown
Allow test programs to determine their thread ID. Signed-off-by: Mark Brown <broonie@kernel.org> Cc: Willy Tarreau <w@1wt.eu> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: x86-64: Use `mov $60,%eax` instead of `mov $60,%rax`Ammar Faizi
Note that mov to 32-bit register will zero extend to 64-bit register. Thus `mov $60,%eax` has the same effect with `mov $60,%rax`. Use the shorter opcode to achieve the same thing. ``` b8 3c 00 00 00 mov $60,%eax (5 bytes) [1] 48 c7 c0 3c 00 00 00 mov $60,%rax (7 bytes) [2] ``` Currently, we use [2]. Change it to [1] for shorter code. Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: x86: Remove `r8`, `r9` and `r10` from the clobber listAmmar Faizi
Linux x86-64 syscall only clobbers rax, rcx and r11 (and "memory"). - rax for the return value. - rcx to save the return address. - r11 to save the rflags. Other registers are preserved. Having r8, r9 and r10 in the syscall clobber list is harmless, but this results in a missed-optimization. As the syscall doesn't clobber r8-r10, GCC should be allowed to reuse their value after the syscall returns to userspace. But since they are in the clobber list, GCC will always miss this opportunity. Remove them from the x86-64 syscall clobber list to help GCC generate better code and fix the comment. See also the x86-64 ABI, section A.2 AMD64 Linux Kernel Conventions, A.2.1 Calling Conventions [1]. Extra note: Some people may think it does not really give a benefit to remove r8, r9 and r10 from the syscall clobber list because the impression of syscall is a C function call, and function call always clobbers those 3. However, that is not the case for nolibc.h, because we have a potential to inline the "syscall" instruction (which its opcode is "0f 05") to the user functions. All syscalls in the nolibc.h are written as a static function with inline ASM and are likely always inline if we use optimization flag, so this is a profit not to have r8, r9 and r10 in the clobber list. Here is the example where this matters. Consider the following C code: ``` #include "tools/include/nolibc/nolibc.h" #define read_abc(a, b, c) __asm__ volatile("nop"::"r"(a),"r"(b),"r"(c)) int main(void) { int a = 0xaa; int b = 0xbb; int c = 0xcc; read_abc(a, b, c); write(1, "test\n", 5); read_abc(a, b, c); return 0; } ``` Compile with: gcc -Os test.c -o test -nostdlib With r8, r9, r10 in the clobber list, GCC generates this: 0000000000001000 <main>: 1000: f3 0f 1e fa endbr64 1004: 41 54 push %r12 1006: 41 bc cc 00 00 00 mov $0xcc,%r12d 100c: 55 push %rbp 100d: bd bb 00 00 00 mov $0xbb,%ebp 1012: 53 push %rbx 1013: bb aa 00 00 00 mov $0xaa,%ebx 1018: 90 nop 1019: b8 01 00 00 00 mov $0x1,%eax 101e: bf 01 00 00 00 mov $0x1,%edi 1023: ba 05 00 00 00 mov $0x5,%edx 1028: 48 8d 35 d1 0f 00 00 lea 0xfd1(%rip),%rsi 102f: 0f 05 syscall 1031: 90 nop 1032: 31 c0 xor %eax,%eax 1034: 5b pop %rbx 1035: 5d pop %rbp 1036: 41 5c pop %r12 1038: c3 ret GCC thinks that syscall will clobber r8, r9, r10. So it spills 0xaa, 0xbb and 0xcc to callee saved registers (r12, rbp and rbx). This is clearly extra memory access and extra stack size for preserving them. But syscall does not actually clobber them, so this is a missed optimization. Now without r8, r9, r10 in the clobber list, GCC generates better code: 0000000000001000 <main>: 1000: f3 0f 1e fa endbr64 1004: 41 b8 aa 00 00 00 mov $0xaa,%r8d 100a: 41 b9 bb 00 00 00 mov $0xbb,%r9d 1010: 41 ba cc 00 00 00 mov $0xcc,%r10d 1016: 90 nop 1017: b8 01 00 00 00 mov $0x1,%eax 101c: bf 01 00 00 00 mov $0x1,%edi 1021: ba 05 00 00 00 mov $0x5,%edx 1026: 48 8d 35 d3 0f 00 00 lea 0xfd3(%rip),%rsi 102d: 0f 05 syscall 102f: 90 nop 1030: 31 c0 xor %eax,%eax 1032: c3 ret Cc: Andy Lutomirski <luto@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: David Laight <David.Laight@ACULAB.COM> Acked-by: Andy Lutomirski <luto@kernel.org> Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id> Link: https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/x86-64-psABI [1] Link: https://lore.kernel.org/lkml/20211011040344.437264-1-ammar.faizi@students.amikom.ac.id/ Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: fix incorrect truncation of exit codeWilly Tarreau
Ammar Faizi reported that our exit code handling is wrong. We truncate it to the lowest 8 bits but the syscall itself is expected to take a regular 32-bit signed integer, not an unsigned char. It's the kernel that later truncates it to the lowest 8 bits. The difference is visible in strace, where the program below used to show exit(255) instead of exit(-1): int main(void) { return -1; } This patch applies the fix to all archs. x86_64, i386, arm64, armv7 and mips were all tested and confirmed to work fine now. Risc-v was not tested but the change is trivial and exactly the same as for other archs. Reported-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id> Cc: stable@vger.kernel.org Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: i386: fix initial stack alignmentWilly Tarreau
After re-checking in the spec and comparing stack offsets with glibc, The last pushed argument must be 16-byte aligned (i.e. aligned before the call) so that in the callee esp+4 is multiple of 16, so the principle is the 32-bit equivalent to what Ammar fixed for x86_64. It's possible that 32-bit code using SSE2 or MMX could have been affected. In addition the frame pointer ought to be zero at the deepest level. Link: https://gitlab.com/x86-psABIs/i386-ABI/-/wikis/Intel386-psABI Cc: Ammar Faizi <ammar.faizi@students.amikom.ac.id> Cc: stable@vger.kernel.org Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-11-30tools/nolibc: x86-64: Fix startup code bugAmmar Faizi
Before this patch, the `_start` function looks like this: ``` 0000000000001170 <_start>: 1170: pop %rdi 1171: mov %rsp,%rsi 1174: lea 0x8(%rsi,%rdi,8),%rdx 1179: and $0xfffffffffffffff0,%rsp 117d: sub $0x8,%rsp 1181: call 1000 <main> 1186: movzbq %al,%rdi 118a: mov $0x3c,%rax 1191: syscall 1193: hlt 1194: data16 cs nopw 0x0(%rax,%rax,1) 119f: nop ``` Note the "and" to %rsp with $-16, it makes the %rsp be 16-byte aligned, but then there is a "sub" with $0x8 which makes the %rsp no longer 16-byte aligned, then it calls main. That's the bug! What actually the x86-64 System V ABI mandates is that right before the "call", the %rsp must be 16-byte aligned, not after the "call". So the "sub" with $0x8 here breaks the alignment. Remove it. An example where this rule matters is when the callee needs to align its stack at 16-byte for aligned move instruction, like `movdqa` and `movaps`. If the callee can't align its stack properly, it will result in segmentation fault. x86-64 System V ABI also mandates the deepest stack frame should be zero. Just to be safe, let's zero the %rbp on startup as the content of %rbp may be unspecified when the program starts. Now it looks like this: ``` 0000000000001170 <_start>: 1170: pop %rdi 1171: mov %rsp,%rsi 1174: lea 0x8(%rsi,%rdi,8),%rdx 1179: xor %ebp,%ebp # zero the %rbp 117b: and $0xfffffffffffffff0,%rsp # align the %rsp 117f: call 1000 <main> 1184: movzbq %al,%rdi 1188: mov $0x3c,%rax 118f: syscall 1191: hlt 1192: data16 cs nopw 0x0(%rax,%rax,1) 119d: nopl (%rax) ``` Cc: Bedirhan KURT <windowz414@gnuweeb.org> Cc: Louvian Lyndal <louvianlyndal@gmail.com> Reported-by: Peter Cordes <peter@cordes.ca> Signed-off-by: Ammar Faizi <ammar.faizi@students.amikom.ac.id> [wt: I did this on purpose due to a misunderstanding of the spec, other archs will thus have to be rechecked, particularly i386] Cc: stable@vger.kernel.org Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-20tools/nolibc: Implement msleep()Mark Brown
Allow users to implement shorter delays than a full second by implementing msleep(). Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2021-07-20tools: include: nolibc: Fix a typo occured to occurred in the file nolibc.hBhaskar Chowdhury
s/occured/occurred/ Signed-off-by: Bhaskar Chowdhury <unixbhaskar@gmail.com> Acked-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Willy Tarreau <w@1wt.eu> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>