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authorMaciej W. Rozycki <macro@linux-mips.org>2015-05-12 15:20:57 +0100
committerRalf Baechle <ralf@linux-mips.org>2015-05-12 23:15:49 +0200
commit03dce595270f22d59a6f37e9170287c1afd94bc2 (patch)
tree68e8ae5e92d6dda9b32be45d72025b095913671d
parent620b155034570f577470cf5309f741bac6a6e32b (diff)
MIPS: Fix a preemption issue with thread's FPU defaults
Fix "BUG: using smp_processor_id() in preemptible" reported in accesses to thread's FPU defaults: the value to initialise FSCR to at program startup, the FCSR r/w mask and the contents of FIR in full FPU emulation, removing a regression introduced with 9b26616c [MIPS: Respect the ISA level in FCSR handling] and f6843626 [MIPS: math-emu: Set FIR feature flags for full emulation]. Use `boot_cpu_data' to obtain the data from, following the approach that `cpu_has_*' macros take and avoiding the call to `smp_processor_id' made in the reference to `current_cpu_data'. The contents of FSCR have to be consistent across processors in an SMP system, the settings there must not change as a thread is migrated across processors. And the contents of FIR are guaranteed to be consistent in FPU emulation, by definition. Signed-off-by: Maciej W. Rozycki <macro@linux-mips.org> Tested-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com> Tested-by: Paul Martin <paul.martin@codethink.co.uk> Cc: Markos Chandras <Markos.Chandras@imgtec.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10030/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
-rw-r--r--arch/mips/include/asm/elf.h4
-rw-r--r--arch/mips/kernel/ptrace.c2
-rw-r--r--arch/mips/math-emu/cp1emu.c4
3 files changed, 5 insertions, 5 deletions
diff --git a/arch/mips/include/asm/elf.h b/arch/mips/include/asm/elf.h
index a594d8ed9698..f19e890b99d2 100644
--- a/arch/mips/include/asm/elf.h
+++ b/arch/mips/include/asm/elf.h
@@ -304,7 +304,7 @@ do { \
\
current->thread.abi = &mips_abi; \
\
- current->thread.fpu.fcr31 = current_cpu_data.fpu_csr31; \
+ current->thread.fpu.fcr31 = boot_cpu_data.fpu_csr31; \
} while (0)
#endif /* CONFIG_32BIT */
@@ -366,7 +366,7 @@ do { \
else \
current->thread.abi = &mips_abi; \
\
- current->thread.fpu.fcr31 = current_cpu_data.fpu_csr31; \
+ current->thread.fpu.fcr31 = boot_cpu_data.fpu_csr31; \
\
p = personality(current->personality); \
if (p != PER_LINUX32 && p != PER_LINUX) \
diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index d544e774eea6..e933a309f2ea 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -176,7 +176,7 @@ int ptrace_setfpregs(struct task_struct *child, __u32 __user *data)
__get_user(value, data + 64);
fcr31 = child->thread.fpu.fcr31;
- mask = current_cpu_data.fpu_msk31;
+ mask = boot_cpu_data.fpu_msk31;
child->thread.fpu.fcr31 = (value & ~mask) | (fcr31 & mask);
/* FIR may not be written. */
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index d31c537ace1d..22b9b2cb9219 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -889,7 +889,7 @@ static inline void cop1_cfc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
break;
case FPCREG_RID:
- value = current_cpu_data.fpu_id;
+ value = boot_cpu_data.fpu_id;
break;
default:
@@ -921,7 +921,7 @@ static inline void cop1_ctc(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
(void *)xcp->cp0_epc, MIPSInst_RT(ir), value);
/* Preserve read-only bits. */
- mask = current_cpu_data.fpu_msk31;
+ mask = boot_cpu_data.fpu_msk31;
fcr31 = (value & ~mask) | (fcr31 & mask);
break;

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