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authorAtsushi Nemoto <anemo@mba.ocn.ne.jp>2007-04-16 23:19:44 +0900
committerRalf Baechle <ralf@linux-mips.org>2007-04-20 14:58:37 +0100
commitfaea62346444ce5b1dba8fb5291d95b676522c42 (patch)
treed00e53763ca9b145348e5754aaf0cd4dcbb12123 /arch/mips/kernel/signal32.c
parent5323180db75d562a287cb2020b07c9422df13df6 (diff)
[MIPS] Retry {save,restore}_fp_context if failed in atomic context.
The save_fp_context()/restore_fp_context() might sleep on accessing user stack and therefore might lose FPU ownership in middle of them. If these function failed due to "in_atomic" test in do_page_fault, touch the sigcontext area in non-atomic context and retry these save/restore operation. This is a replacement of a (broken) fix which was titled "Allow CpU exception in kernel partially". Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp> Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/signal32.c')
-rw-r--r--arch/mips/kernel/signal32.c52
1 files changed, 43 insertions, 9 deletions
diff --git a/arch/mips/kernel/signal32.c b/arch/mips/kernel/signal32.c
index 53a337cfeb66..b9a014411f83 100644
--- a/arch/mips/kernel/signal32.c
+++ b/arch/mips/kernel/signal32.c
@@ -22,6 +22,7 @@
#include <linux/compat.h>
#include <linux/suspend.h>
#include <linux/compiler.h>
+#include <linux/uaccess.h>
#include <asm/abi.h>
#include <asm/asm.h>
@@ -29,7 +30,6 @@
#include <linux/bitops.h>
#include <asm/cacheflush.h>
#include <asm/sim.h>
-#include <asm/uaccess.h>
#include <asm/ucontext.h>
#include <asm/system.h>
#include <asm/fpu.h>
@@ -176,6 +176,46 @@ struct rt_sigframe32 {
/*
* sigcontext handlers
*/
+static int protected_save_fp_context32(struct sigcontext32 __user *sc)
+{
+ int err;
+ while (1) {
+ lock_fpu_owner();
+ own_fpu_inatomic(1);
+ err = save_fp_context32(sc); /* this might fail */
+ unlock_fpu_owner();
+ if (likely(!err))
+ break;
+ /* touch the sigcontext and try again */
+ err = __put_user(0, &sc->sc_fpregs[0]) |
+ __put_user(0, &sc->sc_fpregs[31]) |
+ __put_user(0, &sc->sc_fpc_csr);
+ if (err)
+ break; /* really bad sigcontext */
+ }
+ return err;
+}
+
+static int protected_restore_fp_context32(struct sigcontext32 __user *sc)
+{
+ int err, tmp;
+ while (1) {
+ lock_fpu_owner();
+ own_fpu_inatomic(0);
+ err = restore_fp_context32(sc); /* this might fail */
+ unlock_fpu_owner();
+ if (likely(!err))
+ break;
+ /* touch the sigcontext and try again */
+ err = __get_user(tmp, &sc->sc_fpregs[0]) |
+ __get_user(tmp, &sc->sc_fpregs[31]) |
+ __get_user(tmp, &sc->sc_fpc_csr);
+ if (err)
+ break; /* really bad sigcontext */
+ }
+ return err;
+}
+
static int setup_sigcontext32(struct pt_regs *regs,
struct sigcontext32 __user *sc)
{
@@ -209,10 +249,7 @@ static int setup_sigcontext32(struct pt_regs *regs,
* Save FPU state to signal context. Signal handler
* will "inherit" current FPU state.
*/
- preempt_disable();
- own_fpu(1);
- err |= save_fp_context32(sc);
- preempt_enable();
+ err |= protected_save_fp_context32(sc);
}
return err;
}
@@ -225,10 +262,7 @@ check_and_restore_fp_context32(struct sigcontext32 __user *sc)
err = sig = fpcsr_pending(&sc->sc_fpc_csr);
if (err > 0)
err = 0;
- preempt_disable();
- own_fpu(0);
- err |= restore_fp_context32(sc);
- preempt_enable();
+ err |= protected_restore_fp_context32(sc);
return err ?: sig;
}