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authorFrederic Weisbecker <fweisbec@gmail.com>2010-02-18 10:00:59 -0500
committerFrederic Weisbecker <fweisbec@gmail.com>2010-02-19 12:35:14 -0500
commit84d710926797a6e317e7e94654a3ccd771cfd8a3 (patch)
tree81dbf3f67f75111c00d32f22bd62c251ffdeef91 /arch
parent6f93d0a7c83772997b81c30d6f519a9a5dbab6a9 (diff)
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 <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>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/hw_breakpoint.c30
1 files changed, 7 insertions, 23 deletions
diff --git a/arch/x86/kernel/hw_breakpoint.c b/arch/x86/kernel/hw_breakpoint.c
index 05d5fec64a94..bb6006e3e295 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)
212 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE); 212 return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
213} 213}
214 214
215/*
216 * Store a breakpoint's encoded address, length, and type.
217 */
218static int arch_store_info(struct perf_event *bp)
219{
220 struct arch_hw_breakpoint *info = counter_arch_bp(bp);
221 /*
222 * For kernel-addresses, either the address or symbol name can be
223 * specified.
224 */
225 if (info->name)
226 info->address = (unsigned long)
227 kallsyms_lookup_name(info->name);
228 if (info->address)
229 return 0;
230
231 return -EINVAL;
232}
233
234int arch_bp_generic_fields(int x86_len, int x86_type, 215int arch_bp_generic_fields(int x86_len, int x86_type,
235 int *gen_len, int *gen_type) 216 int *gen_len, int *gen_type)
236{ 217{
@@ -362,10 +343,13 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
362 return ret; 343 return ret;
363 } 344 }
364 345
365 ret = arch_store_info(bp); 346 /*
366 347 * For kernel-addresses, either the address or symbol name can be
367 if (ret < 0) 348 * specified.
368 return ret; 349 */
350 if (info->name)
351 info->address = (unsigned long)
352 kallsyms_lookup_name(info->name);
369 /* 353 /*
370 * Check that the low-order bits of the address are appropriate 354 * Check that the low-order bits of the address are appropriate
371 * for the alignment implied by len. 355 * for the alignment implied by len.