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newlib/libgloss/riscv/sys_stat.c

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RISC-V: Moved syscalls to separate files to fix aliasing problems.
2017-12-26 21:27:52 +01:00
#include <machine/syscall.h>
#include "kernel_stat.h"
#include "internal_syscall.h"
/* Status of a file (by name). */
int
_stat(const char *file, struct stat *st)
{
struct kernel_stat kst;
Only pass the minimum number of syscall arguments Previously, __internal_syscall() compiled into asm-code that unconditionally sets the syscall argument registers a0 to a5. For example, the instruction sequence for a exit syscall looked like this: li a0, 1 # in ther caller of exit() # ... # in newlib: li a1, 0 # unused arguments li a2, 0 li a3, 0 li a4, 0 li a5, 0 li a7, 93 # exit syscall number (i.e. the binary contains then 5 superfluous instructions for this one argument syscall) This commit changes the RISC-V syscall code such that only the required syscall argument registers are set. GCC detects that argc is known at compile time and thus evaluates all the if-statements where argc is used at compile time (tested with -O2 and -Os).
2020-02-10 21:19:58 +01:00
int rv = syscall_errno (SYS_stat, 2, file, &kst, 0, 0, 0, 0);
RISC-V: Moved syscalls to separate files to fix aliasing problems.
2017-12-26 21:27:52 +01:00
_conv_stat (st, &kst);
return rv;
}