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s390: fix fpu restore in entry.S
We need to disable interrupts in load_fpu_regs(). Otherwise an
interrupt might come in after the registers are loaded, but before
CIF_FPU is cleared in load_fpu_regs(). When the interrupt returns,
CIF_FPU will be cleared and the registers will never be restored.
The entry.S code usually saves the interrupt state in __SF_EMPTY on the
stack when disabling/restoring interrupts. sie64a however saves the pointer
to the sie control block in __SF_SIE_CONTROL, which references the same
location. This is non-obvious to the reader. To avoid thrashing the sie
control block pointer in load_fpu_regs(), move the __SIE_* offsets eight
bytes after __SF_EMPTY on the stack.
Cc: <stable@vger.kernel.org> # 5.8
Fixes: 0b0ed657fe
("s390: remove critical section cleanup from entry.S")
Reported-by: Pierre Morel <pmorel@linux.ibm.com>
Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
parent
78d732e1f3
commit
1179f170b6
2 changed files with 7 additions and 5 deletions
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@ -53,11 +53,11 @@ int main(void)
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/* stack_frame offsets */
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/* stack_frame offsets */
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OFFSET(__SF_BACKCHAIN, stack_frame, back_chain);
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OFFSET(__SF_BACKCHAIN, stack_frame, back_chain);
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OFFSET(__SF_GPRS, stack_frame, gprs);
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OFFSET(__SF_GPRS, stack_frame, gprs);
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OFFSET(__SF_EMPTY, stack_frame, empty1);
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OFFSET(__SF_EMPTY, stack_frame, empty1[0]);
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OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[0]);
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OFFSET(__SF_SIE_CONTROL, stack_frame, empty1[1]);
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OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[1]);
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OFFSET(__SF_SIE_SAVEAREA, stack_frame, empty1[2]);
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OFFSET(__SF_SIE_REASON, stack_frame, empty1[2]);
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OFFSET(__SF_SIE_REASON, stack_frame, empty1[3]);
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OFFSET(__SF_SIE_FLAGS, stack_frame, empty1[3]);
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OFFSET(__SF_SIE_FLAGS, stack_frame, empty1[4]);
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BLANK();
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BLANK();
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OFFSET(__VDSO_GETCPU_VAL, vdso_per_cpu_data, getcpu_val);
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OFFSET(__VDSO_GETCPU_VAL, vdso_per_cpu_data, getcpu_val);
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BLANK();
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BLANK();
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@ -1068,6 +1068,7 @@ EXPORT_SYMBOL(save_fpu_regs)
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* %r4
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* %r4
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*/
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*/
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load_fpu_regs:
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load_fpu_regs:
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stnsm __SF_EMPTY(%r15),0xfc
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lg %r4,__LC_CURRENT
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lg %r4,__LC_CURRENT
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aghi %r4,__TASK_thread
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aghi %r4,__TASK_thread
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TSTMSK __LC_CPU_FLAGS,_CIF_FPU
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TSTMSK __LC_CPU_FLAGS,_CIF_FPU
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@ -1099,6 +1100,7 @@ load_fpu_regs:
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.Lload_fpu_regs_done:
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.Lload_fpu_regs_done:
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ni __LC_CPU_FLAGS+7,255-_CIF_FPU
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ni __LC_CPU_FLAGS+7,255-_CIF_FPU
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.Lload_fpu_regs_exit:
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.Lload_fpu_regs_exit:
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ssm __SF_EMPTY(%r15)
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BR_EX %r14
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BR_EX %r14
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.Lload_fpu_regs_end:
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.Lload_fpu_regs_end:
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ENDPROC(load_fpu_regs)
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ENDPROC(load_fpu_regs)
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