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hw-breakpoints: Accept breakpoints on NULL address

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Before we had a generic breakpoint API, ptrace was accepting
breakpoints on NULL address in x86. The new API refuse them,
without given strong reasons. We need to follow the previous
behaviour as some userspace apps like Wine need such NULL
breakpoints to ensure old emulated software protections
are still working.

This fixes a 2.6.32 - 2.6.33-x ptrace regression.

Reported-and-tested-by: Michael Stefaniuc <mstefani@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: K.Prasad <prasad@linux.vnet.ibm.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Maneesh Soni <maneesh@linux.vnet.ibm.com>
Cc: Alexandre Julliard <julliard@winehq.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Maciej Rutecki <maciej.rutecki@gmail.com>
This commit is contained in:
Frederic Weisbecker 2010-02-18 16:00:59 +01:00
parent 6f93d0a7c8
commit 84d7109267
1 changed files with 7 additions and 23 deletions
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30
arch/x86/kernel/hw_breakpoint.c
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@ -212,25 +212,6 @@ static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
/*
* Store a breakpoint's encoded address, length, and type.
*/
static int arch_store_info(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
/*
* For kernel-addresses, either the address or symbol name can be
* specified.
*/
if (info->name)
info->address = (unsigned long)
kallsyms_lookup_name(info->name);
if (info->address)
return 0;
return -EINVAL;
}
int arch_bp_generic_fields(int x86_len, int x86_type,
int *gen_len, int *gen_type)
{
@ -362,10 +343,13 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
return ret;
}
ret = arch_store_info(bp);
if (ret < 0)
return ret;
/*
* For kernel-addresses, either the address or symbol name can be
* specified.
*/
if (info->name)
info->address = (unsigned long)
kallsyms_lookup_name(info->name);
/*
* Check that the low-order bits of the address are appropriate
* for the alignment implied by len.