@@ -917,7 +917,7 @@ void load_system_tables(void)
* Defer checks until exception support is sufficiently set up.
*/
BUILD_BUG_ON((sizeof(struct cpu_info) -
- offsetof(struct cpu_info, guest_cpu_user_regs.es)) & 0xf);
+ sizeof(struct cpu_user_regs)) & 0xf);
BUG_ON(system_state != SYS_STATE_early_boot && (stack_bottom & 0xf));
}
@@ -55,10 +55,6 @@ struct cpu_user_regs
DECL_REG_LO16(flags); /* rflags.IF == !saved_upcall_mask */
DECL_REG_LO8(sp);
uint16_t ss, _pad2[3];
- uint16_t es, _pad3[3];
- uint16_t ds, _pad4[3];
- uint16_t fs, _pad5[3];
- uint16_t gs, _pad6[3];
};
#undef DECL_REG_HI
@@ -106,12 +106,12 @@ static inline struct cpu_info *get_cpu_info(void)
#define get_per_cpu_offset() (get_cpu_info()->per_cpu_offset)
/*
- * Get the bottom-of-stack, as stored in the per-CPU TSS. This actually points
- * into the middle of cpu_info.guest_cpu_user_regs, at the section that
- * precisely corresponds to a CPU trap frame.
+ * Get the bottom-of-stack, as stored in the per-CPU TSS. This points at the
+ * end of cpu_info.guest_cpu_user_regs, at the section that precisely
+ * corresponds to a CPU trap frame.
*/
#define get_stack_bottom() \
- ((unsigned long)&get_cpu_info()->guest_cpu_user_regs.es)
+ ((unsigned long)(&get_cpu_info()->guest_cpu_user_regs + 1))
/*
* Get the reasonable stack bounds for stack traces and stack dumps. Stack
@@ -624,10 +624,6 @@ static inline void hvm_sanitize_regs_fields(struct cpu_user_regs *regs,
regs->saved_upcall_mask = 0xbf;
regs->cs = 0xbeef;
regs->ss = 0xbeef;
- regs->ds = 0xbeef;
- regs->es = 0xbeef;
- regs->fs = 0xbeef;
- regs->gs = 0xbeef;
#endif
}
@@ -20,8 +20,7 @@
(!is_pv_32bit_vcpu(v) ? ((tb)->eip == 0) : (((tb)->cs & ~3) == 0))
/* Number of bytes of on-stack execution state to be context-switched. */
-/* NB. Segment registers and bases are not saved/restored on x86/64 stack. */
-#define CTXT_SWITCH_STACK_BYTES (offsetof(struct cpu_user_regs, es))
+#define CTXT_SWITCH_STACK_BYTES sizeof(struct cpu_user_regs)
#define guest_mode(r) \
({ \
@@ -416,7 +416,7 @@ unsigned long get_stack_trace_bottom(unsigned long sp)
{
case 1 ... 4:
return ROUNDUP(sp, PAGE_SIZE) -
- offsetof(struct cpu_user_regs, es) - sizeof(unsigned long);
+ sizeof(struct cpu_user_regs) - sizeof(unsigned long);
case 6 ... 7:
return ROUNDUP(sp, STACK_SIZE) -
@@ -52,7 +52,7 @@ void __dummy__(void)
OFFSET(UREGS_eflags, struct cpu_user_regs, rflags);
OFFSET(UREGS_rsp, struct cpu_user_regs, rsp);
OFFSET(UREGS_ss, struct cpu_user_regs, ss);
- OFFSET(UREGS_kernel_sizeof, struct cpu_user_regs, es);
+ DEFINE(UREGS_kernel_sizeof, sizeof(struct cpu_user_regs));
BLANK();
/*
@@ -134,17 +134,11 @@ static void _show_registers(
void show_registers(const struct cpu_user_regs *regs)
{
- struct cpu_user_regs fault_regs;
+ struct cpu_user_regs fault_regs = *regs;
struct extra_state fault_state;
enum context context;
struct vcpu *v = system_state >= SYS_STATE_smp_boot ? current : NULL;
- /*
- * Don't read beyond the end of the hardware frame. It is out of bounds
- * for WARN()/etc.
- */
- memcpy(&fault_regs, regs, offsetof(struct cpu_user_regs, es));
-
if ( guest_mode(regs) && is_hvm_vcpu(v) )
{
get_hvm_registers(v, &fault_regs, &fault_state);
The data segment registers are part of the on-stack IRET frame when interrupting Virtual 8086 mode, but this ceased being relevant for Xen in commit 5d1181a5ea5e ("xen: Remove x86_32 build target.") in 2012. With all other cleanup in place, delete the fields so we can introduce FRED support which uses this space for different data. Everywhere which used the es field as an offset in cpu_user_regs needs adjusting. However, they'll change again for FRED, so no cleanup is performed at this juncture. This also undoes the OoB Read workaround in show_registers(), which can now switch back to being simple structure copy. No functional change, but a lot of rearranging of stack and struct layout under the hood. Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> --- CC: Jan Beulich <JBeulich@suse.com> CC: Roger Pau Monné <roger.pau@citrix.com> --- xen/arch/x86/cpu/common.c | 2 +- xen/arch/x86/include/asm/cpu-user-regs.h | 4 ---- xen/arch/x86/include/asm/current.h | 8 ++++---- xen/arch/x86/include/asm/hvm/hvm.h | 4 ---- xen/arch/x86/include/asm/regs.h | 3 +-- xen/arch/x86/traps.c | 2 +- xen/arch/x86/x86_64/asm-offsets.c | 2 +- xen/arch/x86/x86_64/traps.c | 8 +------- 8 files changed, 9 insertions(+), 24 deletions(-)