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x86 mmiotrace: improve handling of secondary faults

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Upgrade some kmmio.c debug messages to warnings.
Allow secondary faults on probed pages to fall through, and only log
secondary faults that are not due to non-present pages.

Patch edited by Pekka Paalanen.

Signed-off-by: Stuart Bennett <stuart@freedesktop.org>
Signed-off-by: Pekka Paalanen <pq@iki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Stuart Bennett 2009-02-05 11:02:02 +00:00 committed by Ingo Molnar
parent 0b700a6a25
commit 3e39aa156a
1 changed files with 22 additions and 18 deletions
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40
arch/x86/mm/kmmio.c
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@ -232,28 +232,32 @@ int kmmio_handler(struct pt_regs *regs, unsigned long addr)
ctx = &get_cpu_var(kmmio_ctx);
if (ctx->active) {
disarm_kmmio_fault_page(faultpage);
if (addr == ctx->addr) {
/*
* On SMP we sometimes get recursive probe hits on the
* same address. Context is already saved, fall out.
* A second fault on the same page means some other
* condition needs handling by do_page_fault(), the
* page really not being present is the most common.
*/
pr_debug("kmmio: duplicate probe hit on CPU %d, for "
"address 0x%08lx.\n",
smp_processor_id(), addr);
ret = 1;
goto no_kmmio_ctx;
}
/*
* Prevent overwriting already in-flight context.
* This should not happen, let's hope disarming at least
* prevents a panic.
*/
pr_emerg("kmmio: recursive probe hit on CPU %d, "
pr_debug("kmmio: secondary hit for 0x%08lx CPU %d.\n",
addr, smp_processor_id());
if (!faultpage->old_presence)
pr_info("kmmio: unexpected secondary hit for "
"address 0x%08lx on CPU %d.\n", addr,
smp_processor_id());
} else {
/*
* Prevent overwriting already in-flight context.
* This should not happen, let's hope disarming at
* least prevents a panic.
*/
pr_emerg("kmmio: recursive probe hit on CPU %d, "
"for address 0x%08lx. Ignoring.\n",
smp_processor_id(), addr);
pr_emerg("kmmio: previous hit was at 0x%08lx.\n",
ctx->addr);
pr_emerg("kmmio: previous hit was at 0x%08lx.\n",
ctx->addr);
disarm_kmmio_fault_page(faultpage);
}
goto no_kmmio_ctx;
}
ctx->active++;
@ -305,7 +309,7 @@ static int post_kmmio_handler(unsigned long condition, struct pt_regs *regs)
struct kmmio_context *ctx = &get_cpu_var(kmmio_ctx);
if (!ctx->active) {
pr_debug("kmmio: spurious debug trap on CPU %d.\n",
pr_warning("kmmio: spurious debug trap on CPU %d.\n",
smp_processor_id());
goto out;
}