From 84d710926797a6e317e7e94654a3ccd771cfd8a3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 18 Feb 2010 16:00:59 +0100 Subject: [PATCH] hw-breakpoints: Accept breakpoints on NULL address 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 Signed-off-by: Frederic Weisbecker Acked-by: K.Prasad Acked-by: Roland McGrath Cc: Alan Stern Cc: Maneesh Soni Cc: Alexandre Julliard Cc: Rafael J. Wysocki Cc: Maciej Rutecki --- arch/x86/kernel/hw_breakpoint.c | 30 +++++++----------------------- 1 file changed, 7 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c index 05d5fec64a9..bb6006e3e29 100644 --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -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. -- 2.20.1