From 14203e19cbc562a79f49117c45c80639a1e65bdd Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sun, 29 Apr 2012 04:11:34 -0400 Subject: microblaze: fix the horror with restarts of sigreturn() solution a-la arm one - pick a callee-saved register (r30), set it non-zero when entering a syscall, have sigreturn wrapper zero it out and pass the value in it to do_notify_resume() as "in_syscall" (actually, "restarts allowed") argument. Note that we don't give a damn about ret_from_fork() - return value is not restart-worthy anyway. Possible remaining bug: on !MMU we still have _debug_exception() restartable. If it hits with -ERESTART_... accidentally in r3, fun happens. MMU does _not_ have _debug_exception() restartable. If that's decided to be a bug (as I strongly suspect it to be), we'll just need to replace setting r30 to 1 with setting r30 to 0 in !MMU _debug_exception(). Up to microblaze maintainers... [folded a fix from Michal] Signed-off-by: Al Viro --- arch/microblaze/kernel/entry.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'arch/microblaze/kernel/entry.S') diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S index c217367dfc7b..18908d29248b 100644 --- a/arch/microblaze/kernel/entry.S +++ b/arch/microblaze/kernel/entry.S @@ -353,6 +353,7 @@ C_ENTRY(_user_exception): /* Figure out which function to use for this system call. */ /* Note Microblaze barrel shift is optional, so don't rely on it */ add r12, r12, r12; /* convert num -> ptr */ + addi r30, r0, 1 /* restarts allowed */ add r12, r12, r12; #ifdef DEBUG @@ -417,7 +418,7 @@ C_ENTRY(ret_from_trap): addik r5, r1, 0; /* Arg 1: struct pt_regs *regs */ bralid r15, do_notify_resume; /* Handle any signals */ - addi r6, r0, 1; /* Arg 2: int in_syscall */ + add r6, r30, r0; /* Arg 2: int in_syscall */ /* Finally, return to user state. */ 1: set_bip; /* Ints masked for state restore */ @@ -464,6 +465,7 @@ C_ENTRY(ret_from_kernel_thread): add r3, r0, r0 C_ENTRY(sys_rt_sigreturn_wrapper): + addik r30, r0, 0 /* no restarts */ brid sys_rt_sigreturn /* Do real work */ addik r5, r1, 0; /* add user context as 1st arg */ -- cgit v1.2.3