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authorAl Viro <viro@zeniv.linux.org.uk>2012-04-29 04:11:34 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2013-02-03 18:16:02 -0500
commit14203e19cbc562a79f49117c45c80639a1e65bdd (patch)
tree758937f82d73a963b9ed0f5979f303c1522195fa /arch/microblaze/kernel
parentc886a9fc1f69c0e53788a9c4a780b6b8825bd4ab (diff)
downloadlinux-14203e19cbc562a79f49117c45c80639a1e65bdd.tar.gz
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>
Diffstat (limited to 'arch/microblaze/kernel')
-rw-r--r--arch/microblaze/kernel/entry-nommu.S5
-rw-r--r--arch/microblaze/kernel/entry.S4
2 files changed, 7 insertions, 2 deletions
diff --git a/arch/microblaze/kernel/entry-nommu.S b/arch/microblaze/kernel/entry-nommu.S
index 29a05d62ec1..96f97f84549 100644
--- a/arch/microblaze/kernel/entry-nommu.S
+++ b/arch/microblaze/kernel/entry-nommu.S
@@ -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
diff --git a/arch/microblaze/kernel/entry.S b/arch/microblaze/kernel/entry.S
index c217367dfc7..18908d29248 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 */