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authorWill Deacon <will.deacon@arm.com>2011-02-11 16:01:42 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-02-11 22:54:48 +0000
commit66e1cfe6d52c69d317e9df76ebc8538a34af0d51 (patch)
tree18ff75aa8b93be0a994402cd9e447a11e7f8eba8 /arch/arm
parented19b739c5c76ad241d30f6c6a5ee96fb284f4cf (diff)
downloadlinux-linaro-66e1cfe6d52c69d317e9df76ebc8538a34af0d51.tar.gz
ARM: 6657/1: hw_breakpoint: fix ptrace breakpoint advertising on unsupported arch
The ptrace debug information register was advertising breakpoint and watchpoint resources for unsupported debug architectures. This meant that setting breakpoints on these architectures would appear to succeed, although they would never fire in reality. This patch fixes the breakpoint slot probing so that it returns 0 when running on an unsupported debug architecture. Reported-by: Ulrich Weigand <ulrich.weigand@de.ibm.com> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm')
-rw-r--r--arch/arm/kernel/hw_breakpoint.c18
1 files changed, 13 insertions, 5 deletions
diff --git a/arch/arm/kernel/hw_breakpoint.c b/arch/arm/kernel/hw_breakpoint.c
index ab02d8aadb7..d600bd35070 100644
--- a/arch/arm/kernel/hw_breakpoint.c
+++ b/arch/arm/kernel/hw_breakpoint.c
@@ -137,11 +137,10 @@ static u8 get_debug_arch(void)
u32 didr;
/* Do we implement the extended CPUID interface? */
- if (((read_cpuid_id() >> 16) & 0xf) != 0xf) {
- pr_warning("CPUID feature registers not supported. "
- "Assuming v6 debug is present.\n");
+ if (WARN_ONCE((((read_cpuid_id() >> 16) & 0xf) != 0xf),
+ "CPUID feature registers not supported. "
+ "Assuming v6 debug is present.\n"))
return ARM_DEBUG_ARCH_V6;
- }
ARM_DBG_READ(c0, 0, didr);
return (didr >> 16) & 0xf;
@@ -152,6 +151,12 @@ u8 arch_get_debug_arch(void)
return debug_arch;
}
+static int debug_arch_supported(void)
+{
+ u8 arch = get_debug_arch();
+ return arch >= ARM_DEBUG_ARCH_V6 && arch <= ARM_DEBUG_ARCH_V7_ECP14;
+}
+
/* Determine number of BRP register available. */
static int get_num_brp_resources(void)
{
@@ -268,6 +273,9 @@ out:
int hw_breakpoint_slots(int type)
{
+ if (!debug_arch_supported())
+ return 0;
+
/*
* We can be called early, so don't rely on
* our static variables being initialised.
@@ -882,7 +890,7 @@ static int __init arch_hw_breakpoint_init(void)
debug_arch = get_debug_arch();
- if (debug_arch > ARM_DEBUG_ARCH_V7_ECP14) {
+ if (!debug_arch_supported()) {
pr_info("debug architecture 0x%x unsupported.\n", debug_arch);
return 0;
}