diff options
| author |   Andy Lutomirski <luto@kernel.org> | 2020-07-03 10:02:55 -0700 |
|---|---|---|
| committer |   Thomas Gleixner <tglx@linutronix.de> | 2020-07-04 19:47:25 +0200 |
| commit | f41f0824224eb12ad84de8972962dd54be5abe3b (patch) | |
| tree | 6cf0f72f726f716884553c14fbc6318318de5776 /arch/x86/xen | |
| parent | x86/entry, selftests: Further improve user entry sanity checks (diff) | |
| download | linux-dev-f41f0824224eb12ad84de8972962dd54be5abe3b.tar.xz linux-dev-f41f0824224eb12ad84de8972962dd54be5abe3b.zip | |
x86/entry/xen: Route #DB correctly on Xen PV
On Xen PV, #DB doesn't use IST. It still needs to be correctly routed
depending on whether it came from user or kernel mode.
Get rid of DECLARE/DEFINE_IDTENTRY_XEN -- it was too hard to follow the
logic. Instead, route #DB and NMI through DECLARE/DEFINE_IDTENTRY_RAW on
Xen, and do the right thing for #DB. Also add more warnings to the
exc_debug* handlers to make this type of failure more obvious.
This fixes various forms of corruption that happen when usermode
triggers #DB on Xen PV.
Fixes: 4c0dcd8350a0 ("x86/entry: Implement user mode C entry points for #DB and #MCE")
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/4163e733cce0b41658e252c6c6b3464f33fdff17.1593795633.git.luto@kernel.org
Diffstat (limited to 'arch/x86/xen')
| -rw-r--r-- | arch/x86/xen/enlighten_pv.c | 28 | ||||
| -rw-r--r-- | arch/x86/xen/xen-asm_64.S | 5 |
2 files changed, 26 insertions, 7 deletions
diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c index acc49fa6a097..0d68948c82ad 100644 --- a/arch/x86/xen/enlighten_pv.c +++ b/arch/x86/xen/enlighten_pv.c @@ -598,6 +598,26 @@ static void xen_write_ldt_entry(struct desc_struct *dt, int entrynum, } #ifdef CONFIG_X86_64 +void noist_exc_debug(struct pt_regs *regs); + +DEFINE_IDTENTRY_RAW(xenpv_exc_nmi) +{ + /* On Xen PV, NMI doesn't use IST. The C part is the sane as native. */ + exc_nmi(regs); +} + +DEFINE_IDTENTRY_RAW(xenpv_exc_debug) +{ + /* + * There's no IST on Xen PV, but we still need to dispatch + * to the correct handler. + */ + if (user_mode(regs)) + noist_exc_debug(regs); + else + exc_debug(regs); +} + struct trap_array_entry { void (*orig)(void); void (*xen)(void); @@ -609,18 +629,18 @@ struct trap_array_entry { .xen = xen_asm_##func, \ .ist_okay = ist_ok } -#define TRAP_ENTRY_REDIR(func, xenfunc, ist_ok) { \ +#define TRAP_ENTRY_REDIR(func, ist_ok) { \ .orig = asm_##func, \ - .xen = xen_asm_##xenfunc, \ + .xen = xen_asm_xenpv_##func, \ .ist_okay = ist_ok } static struct trap_array_entry trap_array[] = { - TRAP_ENTRY_REDIR(exc_debug, exc_xendebug, true ), + TRAP_ENTRY_REDIR(exc_debug, true ), TRAP_ENTRY(exc_double_fault, true ), #ifdef CONFIG_X86_MCE TRAP_ENTRY(exc_machine_check, true ), #endif - TRAP_ENTRY_REDIR(exc_nmi, exc_xennmi, true ), + TRAP_ENTRY_REDIR(exc_nmi, true ), TRAP_ENTRY(exc_int3, false ), TRAP_ENTRY(exc_overflow, false ), #ifdef CONFIG_IA32_EMULATION diff --git a/arch/x86/xen/xen-asm_64.S b/arch/x86/xen/xen-asm_64.S index e1e1c7eafa60..aab1d99b2b48 100644 --- a/arch/x86/xen/xen-asm_64.S +++ b/arch/x86/xen/xen-asm_64.S @@ -29,10 +29,9 @@ _ASM_NOKPROBE(xen_\name) .endm xen_pv_trap asm_exc_divide_error -xen_pv_trap asm_exc_debug -xen_pv_trap asm_exc_xendebug +xen_pv_trap asm_xenpv_exc_debug xen_pv_trap asm_exc_int3 -xen_pv_trap asm_exc_xennmi +xen_pv_trap asm_xenpv_exc_nmi xen_pv_trap asm_exc_overflow xen_pv_trap asm_exc_bounds xen_pv_trap asm_exc_invalid_op |