openkylin
/
linux
mirror of https://gitee.com/openkylin/linux.git
9
0
Fork 0
Code Issues Projects Releases Wiki Activity

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 <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2012-04-29 04:11:34 -04:00
parent c886a9fc1f
commit 14203e19cb
2 changed files with 7 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
arch/microblaze/kernel/entry-nommu.S
View File

@ -280,6 +280,7 @@ 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 */
addik r30, r0, 1 /* restarts allowed */
add r12, r12, r12
lwi r12, r12, sys_call_table /* Get function pointer */
addik r15, r0, ret_to_user-8 /* set return address */
@ -369,6 +370,7 @@ ENTRY(_debug_exception)
bralid r15, send_sig
add r7, r0, r0 /* 3rd param zero */
addik r30, r0, 1 /* restarts allowed ??? */
/* Restore r3/r4 to work around how ret_to_user works */
lwi r3, r1, PT_R3
lwi r4, r1, PT_R4
@ -492,7 +494,7 @@ work_pending:
nop
1: andi r11, r19, _TIF_SIGPENDING | _TIF_NOTIFY_RESUME
beqi r11, no_work_pending
addk r5, r1, r0
addk r5, r30, r0
bralid r15, do_notify_resume
addik r6, r0, 1
bri no_work_pending
@ -562,6 +564,7 @@ no_work_pending:
nop
sys_rt_sigreturn_wrapper:
addk r30, r0, r0 /* no restarts for this one */
brid sys_rt_sigreturn
addk r5, r1, r0

4
arch/microblaze/kernel/entry.S
View File

@ -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 */