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authorOleg Nesterov <oleg@redhat.com>2014-05-12 18:24:45 +0200
committerOleg Nesterov <oleg@redhat.com>2014-05-14 13:57:28 +0200
commitb02ef20a9fba08948e643d3eec0efadf1da01a44 (patch)
treed0db097668940dce698fec8b00d228cd29c1dee0 /kernel
parent0eb14833d5b1ea1accfeffb71be5de5929f85da9 (diff)
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uprobes/x86: Fix the wrong ->si_addr when xol triggers a trap
If the probed insn triggers a trap, ->si_addr = regs->ip is technically correct, but this is not what the signal handler wants; we need to pass the address of the probed insn, not the address of xol slot. Add the new arch-agnostic helper, uprobe_get_trap_addr(), and change fill_trap_info() and math_error() to use it. !CONFIG_UPROBES case in uprobes.h uses a macro to avoid include hell and ensure that it can be compiled even if an architecture doesn't define instruction_pointer(). Test-case: #include <signal.h> #include <stdio.h> #include <unistd.h> extern void probe_div(void); void sigh(int sig, siginfo_t *info, void *c) { int passed = (info->si_addr == probe_div); printf(passed ? "PASS\n" : "FAIL\n"); _exit(!passed); } int main(void) { struct sigaction sa = { .sa_sigaction = sigh, .sa_flags = SA_SIGINFO, }; sigaction(SIGFPE, &sa, NULL); asm ( "xor %ecx,%ecx\n" ".globl probe_div; probe_div:\n" "idiv %ecx\n" ); return 0; } it fails if probe_div() is probed. Note: show_unhandled_signals users should probably use this helper too, but we need to cleanup them first. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/events/uprobes.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index a13251e8bfa4..3b02c72938a8 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -1351,6 +1351,16 @@ unsigned long __weak uprobe_get_swbp_addr(struct pt_regs *regs)
return instruction_pointer(regs) - UPROBE_SWBP_INSN_SIZE;
}
+unsigned long uprobe_get_trap_addr(struct pt_regs *regs)
+{
+ struct uprobe_task *utask = current->utask;
+
+ if (unlikely(utask && utask->active_uprobe))
+ return utask->vaddr;
+
+ return instruction_pointer(regs);
+}
+
/*
* Called with no locks held.
* Called in context of a exiting or a exec-ing thread.