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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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25edd6946a
This is based upon a report by Meelis Roos showing that it's possible that we'll try to fetch a property that is 32K in size with some devices. With the current fixed 3K buffer we use for moving data in and out of the firmware during PROM calls, that simply won't work. In fact, it will scramble random kernel data during bootup. The reasoning behind the temporary buffer is entirely historical. It used to be the case that we had problems referencing dynamic kernel memory (including the stack) early in the boot process before we explicitly told the firwmare to switch us over to the kernel trap table. So what we did was always give the firmware buffers that were locked into the main kernel image. But we no longer have problems like that, so get rid of all of this indirect bounce buffering. Besides fixing Meelis's bug, this also makes the kernel data about 3K smaller. It was also discovered during these conversions that the implementation of prom_retain() was completely wrong, so that was fixed here as well. Currently that interface is not in use. Reported-by: Meelis Roos <mroos@linux.ee> Tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: David S. Miller <davem@davemloft.net>
58 lines
1.2 KiB
C
58 lines
1.2 KiB
C
/*
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* p1275.c: Sun IEEE 1275 PROM low level interface routines
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*
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* Copyright (C) 1996,1997 Jakub Jelinek (jj@sunsite.mff.cuni.cz)
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*/
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#include <linux/kernel.h>
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#include <linux/init.h>
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#include <linux/sched.h>
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#include <linux/smp.h>
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#include <linux/string.h>
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#include <linux/spinlock.h>
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#include <asm/openprom.h>
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#include <asm/oplib.h>
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#include <asm/system.h>
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#include <asm/spitfire.h>
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#include <asm/pstate.h>
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#include <asm/ldc.h>
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struct {
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long prom_callback; /* 0x00 */
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void (*prom_cif_handler)(long *); /* 0x08 */
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unsigned long prom_cif_stack; /* 0x10 */
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} p1275buf;
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extern void prom_world(int);
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extern void prom_cif_direct(unsigned long *args);
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extern void prom_cif_callback(void);
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/*
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* This provides SMP safety on the p1275buf.
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*/
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DEFINE_RAW_SPINLOCK(prom_entry_lock);
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void p1275_cmd_direct(unsigned long *args)
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{
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unsigned long flags;
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raw_local_save_flags(flags);
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raw_local_irq_restore(PIL_NMI);
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raw_spin_lock(&prom_entry_lock);
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prom_world(1);
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prom_cif_direct(args);
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prom_world(0);
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raw_spin_unlock(&prom_entry_lock);
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raw_local_irq_restore(flags);
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}
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void prom_cif_init(void *cif_handler, void *cif_stack)
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{
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p1275buf.prom_cif_handler = (void (*)(long *))cif_handler;
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p1275buf.prom_cif_stack = (unsigned long)cif_stack;
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}
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