The function only saves initial arch-specific "no FIQ" instruction, by placing the code into set_fiq_handler() we can:
- Have less code and logic in the platform-specific files;
- Have the code that manages FIQ vector overwriting in one place, i.e. don't spread the logic around.
p.s. Also, I noticed that we saved no_fiq_insn w/o bothering about !CONFIG_CPU_USE_DOMAINS case, but set_fiq_handler() handles this case specifically. I wonder, was that on purpose, e.g. it does not matter for init_FIQ(), or it was just overlooked? In the latter case, the patch fixes the issue.
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diff --git a/arch/arm/kernel/fiq.c b/arch/arm/kernel/fiq.c index 9bf3a60..3602df6 100644 --- a/arch/arm/kernel/fiq.c +++ b/arch/arm/kernel/fiq.c @@ -49,6 +49,7 @@ #include <asm/mach/irq.h> static unsigned long no_fiq_insn; +static int got_no_fiq_insn; /* Default reacquire function
- we always relinquish FIQ control
@@ -78,11 +79,14 @@ void show_fiq_list(struct seq_file *p, int prec) void set_fiq_handler(void *start, unsigned int length) { -#if defined(CONFIG_CPU_USE_DOMAINS)
- memcpy((void *)0xffff001c, start, length);
-#else
- memcpy(vectors_page + 0x1c, start, length);
- unsigned long *addr = (void *)0xffff001c;
+#ifndef CONFIG_CPU_USE_DOMAINS
- addr = vectors_page + 0x1c;
#endif
- if (!cmpxchg(&got_no_fiq_insn, 0, 1))
no_fiq_insn = *addr;- memcpy(addr, start, length); flush_icache_range(0xffff001c, 0xffff001c + length); if (!vectors_high()) flush_icache_range(0x1c, 0x1c + length);
@@ -126,8 +130,3 @@ EXPORT_SYMBOL(__set_fiq_regs); /* defined in fiqasm.S */ EXPORT_SYMBOL(__get_fiq_regs); /* defined in fiqasm.S */ EXPORT_SYMBOL(claim_fiq); EXPORT_SYMBOL(release_fiq);
-void __init init_FIQ(void) -{
- no_fiq_insn = *(unsigned long *)0xffff001c;
it seems that this is wrong. In this case we have an uninitialized variable and sequential call claim_fiq and release_fiq could be fatal. FIXME please.
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