diff options
| author | Atsushi Nemoto <anemo@mba.ocn.ne.jp> | 2007-04-16 16:19:44 +0200 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2007-04-20 15:58:37 +0200 |
| commit | faea62346444ce5b1dba8fb5291d95b676522c42 (patch) | |
| tree | d00e53763ca9b145348e5754aaf0cd4dcbb12123 /arch/mips/kernel/signal.c | |
| parent | [MIPS] Disallow CpU exception in kernel again. (diff) | |
| download | linux-faea62346444ce5b1dba8fb5291d95b676522c42.tar.xz linux-faea62346444ce5b1dba8fb5291d95b676522c42.zip | |
[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/signal.c')
| -rw-r--r-- | arch/mips/kernel/signal.c | 52 |
1 files changed, 43 insertions, 9 deletions
diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c index fa581192de21..07d67309451a 100644 --- a/arch/mips/kernel/signal.c +++ b/arch/mips/kernel/signal.c @@ -20,6 +20,7 @@ #include <linux/ptrace.h> #include <linux/unistd.h> #include <linux/compiler.h> +#include <linux/uaccess.h> #include <asm/abi.h> #include <asm/asm.h> @@ -27,7 +28,6 @@ #include <asm/cacheflush.h> #include <asm/fpu.h> #include <asm/sim.h> -#include <asm/uaccess.h> #include <asm/ucontext.h> #include <asm/cpu-features.h> #include <asm/war.h> @@ -78,6 +78,46 @@ struct rt_sigframe { /* * Helper routines */ +static int protected_save_fp_context(struct sigcontext __user *sc) +{ + int err; + while (1) { + lock_fpu_owner(); + own_fpu_inatomic(1); + err = save_fp_context(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_context(struct sigcontext __user *sc) +{ + int err, tmp; + while (1) { + lock_fpu_owner(); + own_fpu_inatomic(0); + err = restore_fp_context(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; +} + int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) { int err = 0; @@ -113,10 +153,7 @@ int setup_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc) * Save FPU state to signal context. Signal handler * will "inherit" current FPU state. */ - preempt_disable(); - own_fpu(1); - err |= save_fp_context(sc); - preempt_enable(); + err |= protected_save_fp_context(sc); } return err; } @@ -148,10 +185,7 @@ check_and_restore_fp_context(struct sigcontext __user *sc) err = sig = fpcsr_pending(&sc->sc_fpc_csr); if (err > 0) err = 0; - preempt_disable(); - own_fpu(0); - err |= restore_fp_context(sc); - preempt_enable(); + err |= protected_restore_fp_context(sc); return err ?: sig; } |