From 84d710926797a6e317e7e94654a3ccd771cfd8a3 Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 18 Feb 2010 16:00:59 +0100 Subject: 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(-) (limited to 'arch/x86') 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. -- cgit v1.2.3-70-g09d2 From 326264a02448b0ac51f78f178b78e830aa077a0b Mon Sep 17 00:00:00 2001 From: Frederic Weisbecker Date: Thu, 18 Feb 2010 18:24:18 +0100 Subject: hw-breakpoint: Keep track of dr7 local enable bits When the user enables breakpoints through dr7, he can choose between "local" or "global" enable bits but given how linux is implemented, both have the same effect. That said we don't keep track how the user enabled the breakpoints so when the user requests the dr7 value, we only translate the "enabled" status using the global enabled bits. It means that if the user enabled a breakpoint using the local enabled bit, reading back dr7 will set the global bit and clear the local one. Apps like Wine expect a full dr7 POKEUSER/PEEKUSER match for emulated softwares that implement old reverse engineering protection schemes. We fix that by keeping track of the whole dr7 value given by the user in the thread structure to drop this bug. We'll think about something more proper later. 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 Cc: Alan Stern Cc: Maneesh Soni Cc: Alexandre Julliard Cc: Rafael J. Wysocki Cc: Maciej Rutecki --- arch/x86/include/asm/processor.h | 2 ++ arch/x86/kernel/ptrace.c | 7 +++++-- 2 files changed, 7 insertions(+), 2 deletions(-) (limited to 'arch/x86') diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index fc801bab1b3..b753ea59703 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -450,6 +450,8 @@ struct thread_struct { struct perf_event *ptrace_bps[HBP_NUM]; /* Debug status used for traps, single steps, etc... */ unsigned long debugreg6; + /* Keep track of the exact dr7 value set by the user */ + unsigned long ptrace_dr7; /* Fault info: */ unsigned long cr2; unsigned long trap_no; diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 017d937639f..0c1033d61e5 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -702,7 +702,7 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) } else if (n == 6) { val = thread->debugreg6; } else if (n == 7) { - val = ptrace_get_dr7(thread->ptrace_bps); + val = thread->ptrace_dr7; } return val; } @@ -778,8 +778,11 @@ int ptrace_set_debugreg(struct task_struct *tsk, int n, unsigned long val) return rc; } /* All that's left is DR7 */ - if (n == 7) + if (n == 7) { rc = ptrace_write_dr7(tsk, val); + if (!rc) + thread->ptrace_dr7 = val; + } ret_path: return rc; -- cgit v1.2.3-70-g09d2