| Message ID | 1343254238-4727-11-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
On 25 July 2012 23:10, Richard Henderson <rth@twiddle.net> wrote: > Alpha uses unbiased priority values in the syscall, with the a3 > return value signaling error conditions. Therefore, properly > interpret the libc getpriority as needed for the guest rather > than passing the host value through unchanged. > > Signed-off-by: Richard Henderson <rth@twiddle.net> > --- > linux-user/syscall.c | 20 +++++++++++++++----- > 1 files changed, 15 insertions(+), 5 deletions(-) > > diff --git a/linux-user/syscall.c b/linux-user/syscall.c > index 2e1c1c0..b487635 100644 > --- a/linux-user/syscall.c > +++ b/linux-user/syscall.c > @@ -218,7 +218,6 @@ _syscall3(int, sys_getdents, uint, fd, struct linux_dirent *, dirp, uint, count) > #if defined(TARGET_NR_getdents64) && defined(__NR_getdents64) > _syscall3(int, sys_getdents64, uint, fd, struct linux_dirent64 *, dirp, uint, count); > #endif > -_syscall2(int, sys_getpriority, int, which, int, who); > #if defined(TARGET_NR__llseek) && defined(__NR_llseek) > _syscall5(int, _llseek, uint, fd, ulong, hi, ulong, lo, > loff_t *, res, uint, wh); > @@ -6445,10 +6444,21 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, > break; > #endif > case TARGET_NR_getpriority: > - /* libc does special remapping of the return value of > - * sys_getpriority() so it's just easiest to call > - * sys_getpriority() directly rather than through libc. */ > - ret = get_errno(sys_getpriority(arg1, arg2)); > + /* Note that negative values are valid for getpriority, so we must > + differentiate based on errno settings. */ > + errno = 0; > + ret = getpriority(arg1, arg2); > + if (ret == -1 && errno != 0) { > + ret = get_errno(errno); > + break; > + } > +#ifdef TARGET_ALPHA > + /* Return value is the unbiased priority. Signal no error. */ > + ((CPUAlphaState *)cpu_env)->ir[IR_V0] = 0; Having do_syscall fish around in the cpu register struct seems a bit ugly, but we do it elsewhere so I guess this is OK. > +#else > + /* Return value is a biased priority to avoid negative numbers. */ > + ret = 20 - ret; > +#endif > break; > case TARGET_NR_setpriority: > ret = get_errno(setpriority(arg1, arg2, arg3)); Sanity check -- it is only getpriority that has the biasing, not setpriority? -- PMM
On 2012-08-02 07:48, Peter Maydell wrote:
> Sanity check -- it is only getpriority that has the biasing, not setpriority?
Correct.
r~
diff --git a/linux-user/syscall.c b/linux-user/syscall.c index 2e1c1c0..b487635 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -218,7 +218,6 @@ _syscall3(int, sys_getdents, uint, fd, struct linux_dirent *, dirp, uint, count) #if defined(TARGET_NR_getdents64) && defined(__NR_getdents64) _syscall3(int, sys_getdents64, uint, fd, struct linux_dirent64 *, dirp, uint, count); #endif -_syscall2(int, sys_getpriority, int, which, int, who); #if defined(TARGET_NR__llseek) && defined(__NR_llseek) _syscall5(int, _llseek, uint, fd, ulong, hi, ulong, lo, loff_t *, res, uint, wh); @@ -6445,10 +6444,21 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, break; #endif case TARGET_NR_getpriority: - /* libc does special remapping of the return value of - * sys_getpriority() so it's just easiest to call - * sys_getpriority() directly rather than through libc. */ - ret = get_errno(sys_getpriority(arg1, arg2)); + /* Note that negative values are valid for getpriority, so we must + differentiate based on errno settings. */ + errno = 0; + ret = getpriority(arg1, arg2); + if (ret == -1 && errno != 0) { + ret = get_errno(errno); + break; + } +#ifdef TARGET_ALPHA + /* Return value is the unbiased priority. Signal no error. */ + ((CPUAlphaState *)cpu_env)->ir[IR_V0] = 0; +#else + /* Return value is a biased priority to avoid negative numbers. */ + ret = 20 - ret; +#endif break; case TARGET_NR_setpriority: ret = get_errno(setpriority(arg1, arg2, arg3));
Alpha uses unbiased priority values in the syscall, with the a3 return value signaling error conditions. Therefore, properly interpret the libc getpriority as needed for the guest rather than passing the host value through unchanged. Signed-off-by: Richard Henderson <rth@twiddle.net> --- linux-user/syscall.c | 20 +++++++++++++++----- 1 files changed, 15 insertions(+), 5 deletions(-)