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authorFrederic Weisbecker <fweisbec@gmail.com>2010-04-18 18:11:53 +0200
committerFrederic Weisbecker <fweisbec@gmail.com>2010-05-01 04:32:10 +0200
commitb2812d031dea86926e9c10f7714af33ac2f6b43d (patch)
treea48b18b49fa064e89b7b03e057e46e5a294a8053 /arch/sh/kernel/hw_breakpoint.c
parenthw-breakpoints: Check disabled breakpoints again (diff)
downloadlinux-dev-b2812d031dea86926e9c10f7714af33ac2f6b43d.tar.xz
linux-dev-b2812d031dea86926e9c10f7714af33ac2f6b43d.zip
hw-breakpoints: Change/Enforce some breakpoints policies
The current policies of breakpoints in x86 and SH are the following: - task bound breakpoints can only break on userspace addresses - cpu wide breakpoints can only break on kernel addresses The former rule prevents ptrace breakpoints to be set to trigger on kernel addresses, which is good. But as a side effect, we can't breakpoint on kernel addresses for task bound breakpoints. The latter rule simply makes no sense, there is no reason why we can't set breakpoints on userspace while performing cpu bound profiles. We want the following new policies: - task bound breakpoint can set userspace address breakpoints, with no particular privilege required. - task bound breakpoints can set kernelspace address breakpoints but must be privileged to do that. - cpu bound breakpoints can do what they want as they are privileged already. To implement these new policies, this patch checks if we are dealing with a kernel address breakpoint, if so and if the exclude_kernel parameter is set, we tell the user that the breakpoint is invalid, which makes a good generic ptrace protection. If we don't have exclude_kernel, ensure the user has the right privileges as kernel breakpoints are quite sensitive (risk of trap recursion attacks and global performance impacts). [ Paul Mundt: keep addr space check for sh signal delivery and fix double function declaration] Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com> Cc: K. Prasad <prasad@linux.vnet.ibm.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Jason Wessel <jason.wessel@windriver.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Diffstat (limited to '')
-rw-r--r--arch/sh/kernel/hw_breakpoint.c34
1 files changed, 7 insertions, 27 deletions
diff --git a/arch/sh/kernel/hw_breakpoint.c b/arch/sh/kernel/hw_breakpoint.c
index 675eea7785d9..1f2cf6229862 100644
--- a/arch/sh/kernel/hw_breakpoint.c
+++ b/arch/sh/kernel/hw_breakpoint.c
@@ -120,25 +120,16 @@ static int get_hbp_len(u16 hbp_len)
}
/*
- * Check for virtual address in user space.
- */
-int arch_check_va_in_userspace(unsigned long va, u16 hbp_len)
-{
- unsigned int len;
-
- len = get_hbp_len(hbp_len);
-
- return (va <= TASK_SIZE - len);
-}
-
-/*
* Check for virtual address in kernel space.
*/
-static int arch_check_va_in_kernelspace(unsigned long va, u8 hbp_len)
+int arch_check_bp_in_kernelspace(struct perf_event *bp)
{
unsigned int len;
+ unsigned long va;
+ struct arch_hw_breakpoint *info = counter_arch_bp(bp);
- len = get_hbp_len(hbp_len);
+ va = info->address;
+ len = get_hbp_len(info->len);
return (va >= TASK_SIZE) && ((va + len - 1) >= TASK_SIZE);
}
@@ -226,8 +217,7 @@ static int arch_build_bp_info(struct perf_event *bp)
/*
* Validate the arch-specific HW Breakpoint register settings
*/
-int arch_validate_hwbkpt_settings(struct perf_event *bp,
- struct task_struct *tsk)
+int arch_validate_hwbkpt_settings(struct perf_event *bp)
{
struct arch_hw_breakpoint *info = counter_arch_bp(bp);
unsigned int align;
@@ -270,15 +260,6 @@ int arch_validate_hwbkpt_settings(struct perf_event *bp,
if (info->address & align)
return -EINVAL;
- /* Check that the virtual address is in the proper range */
- if (tsk) {
- if (!arch_check_va_in_userspace(info->address, info->len))
- return -EFAULT;
- } else {
- if (!arch_check_va_in_kernelspace(info->address, info->len))
- return -EFAULT;
- }
-
return 0;
}
@@ -363,8 +344,7 @@ static int __kprobes hw_breakpoint_handler(struct die_args *args)
perf_bp_event(bp, args->regs);
/* Deliver the signal to userspace */
- if (arch_check_va_in_userspace(bp->attr.bp_addr,
- bp->attr.bp_len)) {
+ if (!arch_check_bp_in_kernelspace(bp)) {
siginfo_t info;
info.si_signo = args->signr;