Commit-ID: d0cd64b02aa854d68ce517cb7da1fe4e4fff2653
Gitweb: https://git.kernel.org/tip/d0cd64b02aa854d68ce517cb7da1fe4e4fff2653
Author: Yonghong Song <yhs@xxxxxx>
AuthorDate: Wed, 8 Nov 2017 11:28:45 -0800
Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
CommitDate: Wed, 8 Nov 2017 21:05:23 +0100
x86/idt: Remove X86_TRAP_BP initialization in idt_setup_traps()
Commit b70543a0b2b6("x86/idt: Move regular trap init to tables") moves
regular trap init for each trap vector into a table based
initialization. It introduced the initialization for vector X86_TRAP_BP
which was not in the code which it replaced. This breaks uprobe
functionality for x86_32; the probed program segfaults instead of handling
the probe proper.
The reason for this is that TRAP_BP is set up as system interrupt gate
(DPL3) in the early IDT and then replaced by a regular interrupt gate
(DPL0) in idt_setup_traps(). The DPL0 restriction causes the int3 trap
to fail with a #GP resulting in a SIGSEGV of the probed program.
On 64bit this does not cause a problem because the IDT entry is replaced
with a system interrupt gate (DPL3) with interrupt stack afterwards.
Remove X86_TRAP_BP from the def_idts table which is used in
idt_setup_traps(). Remove a redundant entry for X86_TRAP_NMI in def_idts
while at it. Tested on both x86_64 and x86_32.
[ tglx: Amended changelog with a description of the root cause ]
Fixes: b70543a0b2b6("x86/idt: Move regular trap init to tables")
Reported-and-tested-by: Yonghong Song <yhs@xxxxxx>
Signed-off-by: Yonghong Song <yhs@xxxxxx>
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: a.p.zijlstra@xxxxxxxxx
Cc: ast@xxxxxx
Cc: oleg@xxxxxxxxxx
Cc: luto@xxxxxxxxxx
Cc: kernel-team@xxxxxx
Link: https://lkml.kernel.org/r/20171108192845.552709-1-yhs@xxxxxx
---
arch/x86/kernel/idt.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/kernel/idt.c b/arch/x86/kernel/idt.c
index 6107ee1..014cb2f 100644
--- a/arch/x86/kernel/idt.c
+++ b/arch/x86/kernel/idt.c
@@ -92,8 +92,6 @@ static const __initdata struct idt_data def_idts[] = {
INTG(X86_TRAP_DF, double_fault),
#endif
INTG(X86_TRAP_DB, debug),
- INTG(X86_TRAP_NMI, nmi),
- INTG(X86_TRAP_BP, int3),
#ifdef CONFIG_X86_MCE
INTG(X86_TRAP_MC, &machine_check),
--
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