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| author | Masami Hiramatsu <mhiramat@kernel.org> | 2022-03-26 11:27:40 +0900 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-03-28 19:38:51 -0700 |
| commit | 45c23bf4d1a416d32e509f83719a7399e35bdaf9 (patch) | |
| tree | 173ff987862f7193b5b7145b96c510ae3d8841b2 | |
| parent | 0ef6f5c09371f17e142814e6996d6dfb8741925b (diff) | |
| download | linux-45c23bf4d1a416d32e509f83719a7399e35bdaf9.tar.gz linux-45c23bf4d1a416d32e509f83719a7399e35bdaf9.tar.bz2 linux-45c23bf4d1a416d32e509f83719a7399e35bdaf9.zip | |
x86,kprobes: Fix optprobe trampoline to generate complete pt_regs
Currently the optprobe trampoline template code ganerate an
almost complete pt_regs on-stack, everything except regs->ss.
The 'regs->ss' points to the top of stack, which is not a
valid segment decriptor.
As same as the rethook does, complete the job by also pushing ss.
Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/164826166027.2455864.14759128090648961900.stgit@devnote2
| -rw-r--r-- | arch/x86/kernel/kprobes/opt.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/arch/x86/kernel/kprobes/opt.c b/arch/x86/kernel/kprobes/opt.c index b4a54a52aa59..e6b8c5362b94 100644 --- a/arch/x86/kernel/kprobes/opt.c +++ b/arch/x86/kernel/kprobes/opt.c @@ -106,7 +106,8 @@ asm ( ".global optprobe_template_entry\n" "optprobe_template_entry:\n" #ifdef CONFIG_X86_64 - /* We don't bother saving the ss register */ + " pushq $" __stringify(__KERNEL_DS) "\n" + /* Save the 'sp - 8', this will be fixed later. */ " pushq %rsp\n" " pushfq\n" ".global optprobe_template_clac\n" @@ -121,14 +122,17 @@ asm ( ".global optprobe_template_call\n" "optprobe_template_call:\n" ASM_NOP5 - /* Move flags to rsp */ + /* Copy 'regs->flags' into 'regs->ss'. */ " movq 18*8(%rsp), %rdx\n" - " movq %rdx, 19*8(%rsp)\n" + " movq %rdx, 20*8(%rsp)\n" RESTORE_REGS_STRING - /* Skip flags entry */ - " addq $8, %rsp\n" + /* Skip 'regs->flags' and 'regs->sp'. */ + " addq $16, %rsp\n" + /* And pop flags register from 'regs->ss'. */ " popfq\n" #else /* CONFIG_X86_32 */ + " pushl %ss\n" + /* Save the 'sp - 4', this will be fixed later. */ " pushl %esp\n" " pushfl\n" ".global optprobe_template_clac\n" @@ -142,12 +146,13 @@ asm ( ".global optprobe_template_call\n" "optprobe_template_call:\n" ASM_NOP5 - /* Move flags into esp */ + /* Copy 'regs->flags' into 'regs->ss'. */ " movl 14*4(%esp), %edx\n" - " movl %edx, 15*4(%esp)\n" + " movl %edx, 16*4(%esp)\n" RESTORE_REGS_STRING - /* Skip flags entry */ - " addl $4, %esp\n" + /* Skip 'regs->flags' and 'regs->sp'. */ + " addl $8, %esp\n" + /* And pop flags register from 'regs->ss'. */ " popfl\n" #endif ".global optprobe_template_end\n" @@ -179,6 +184,8 @@ optimized_callback(struct optimized_kprobe *op, struct pt_regs *regs) kprobes_inc_nmissed_count(&op->kp); } else { struct kprobe_ctlblk *kcb = get_kprobe_ctlblk(); + /* Adjust stack pointer */ + regs->sp += sizeof(long); /* Save skipped registers */ regs->cs = __KERNEL_CS; #ifdef CONFIG_X86_32 |