On 08/01/15 15:22, Jan Beulich wrote:
> Unused arguments get clobbered before the call (not affecting caller
> visible state), while used arguments get clobbered afterwards unless
> a continuation is needed (affecting caller visible state).
>
> Signed-off-by: Jan Beulich <jbeul...@suse.com>
After a long time pouring over the Microsoft register calling
conventions documentation, and the Windows PV driver code, I am now
convinced that they are performing appropriate parameter saving.
Reviewed-by: Andrew Cooper <andrew.coop...@citrix.com>
>
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -4818,6 +4818,8 @@ static hvm_hypercall_t *const pvh_hyperc
> [ __HYPERVISOR_arch_1 ] = (hvm_hypercall_t *)paging_domctl_continuation
> };
>
> +extern const uint8_t hypercall_args_table[], compat_hypercall_args_table[];
> +
> int hvm_do_hypercall(struct cpu_user_regs *regs)
> {
> struct vcpu *curr = current;
> @@ -4856,36 +4858,95 @@ int hvm_do_hypercall(struct cpu_user_reg
>
> if ( mode == 8 )
> {
> + unsigned long rdi = regs->rdi;
> + unsigned long rsi = regs->rsi;
> + unsigned long rdx = regs->rdx;
> + unsigned long r10 = regs->r10;
> + unsigned long r8 = regs->r8;
> + unsigned long r9 = regs->r9;
> +
> HVM_DBG_LOG(DBG_LEVEL_HCALL, "hcall%u(%lx, %lx, %lx, %lx, %lx, %lx)",
> - eax, regs->rdi, regs->rsi, regs->rdx,
> - regs->r10, regs->r8, regs->r9);
> + eax, rdi, rsi, rdx, r10, r8, r9);
> +
> +#ifndef NDEBUG
> + /* Deliberately corrupt parameter regs not used by this hypercall. */
> + switch ( hypercall_args_table[eax] )
> + {
> + case 0: rdi = 0xdeadbeefdeadf00dUL;
> + case 1: rsi = 0xdeadbeefdeadf00dUL;
> + case 2: rdx = 0xdeadbeefdeadf00dUL;
> + case 3: r10 = 0xdeadbeefdeadf00dUL;
> + case 4: r8 = 0xdeadbeefdeadf00dUL;
> + case 5: r9 = 0xdeadbeefdeadf00dUL;
> + }
> +#endif
>
> curr->arch.hvm_vcpu.hcall_64bit = 1;
> - if ( is_pvh_vcpu(curr) )
> - regs->rax = pvh_hypercall64_table[eax](regs->rdi, regs->rsi,
> - regs->rdx, regs->r10,
> - regs->r8, regs->r9);
> - else
> - regs->rax = hvm_hypercall64_table[eax](regs->rdi, regs->rsi,
> - regs->rdx, regs->r10,
> - regs->r8, regs->r9);
> + regs->rax = (is_pvh_vcpu(curr)
> + ? pvh_hypercall64_table
> + : hvm_hypercall64_table)[eax](rdi, rsi, rdx, r10, r8,
> r9);
> curr->arch.hvm_vcpu.hcall_64bit = 0;
> +
> +#ifndef NDEBUG
> + if ( !curr->arch.hvm_vcpu.hcall_preempted )
> + {
> + /* Deliberately corrupt parameter regs used by this hypercall. */
> + switch ( hypercall_args_table[eax] )
> + {
> + case 6: regs->r9 = 0xdeadbeefdeadf00dUL;
> + case 5: regs->r8 = 0xdeadbeefdeadf00dUL;
> + case 4: regs->r10 = 0xdeadbeefdeadf00dUL;
> + case 3: regs->edx = 0xdeadbeefdeadf00dUL;
> + case 2: regs->esi = 0xdeadbeefdeadf00dUL;
> + case 1: regs->edi = 0xdeadbeefdeadf00dUL;
> + }
> + }
> +#endif
> }
> else if ( unlikely(is_pvh_vcpu(curr)) )
> regs->_eax = -ENOSYS; /* PVH 32bitfixme. */
> else
> {
> + unsigned int ebx = regs->_ebx;
> + unsigned int ecx = regs->_ecx;
> + unsigned int edx = regs->_edx;
> + unsigned int esi = regs->_esi;
> + unsigned int edi = regs->_edi;
> + unsigned int ebp = regs->_ebp;
> +
> HVM_DBG_LOG(DBG_LEVEL_HCALL, "hcall%u(%x, %x, %x, %x, %x, %x)", eax,
> - (uint32_t)regs->ebx, (uint32_t)regs->ecx,
> - (uint32_t)regs->edx, (uint32_t)regs->esi,
> - (uint32_t)regs->edi, (uint32_t)regs->ebp);
> -
> - regs->eax = hvm_hypercall32_table[eax]((uint32_t)regs->ebx,
> - (uint32_t)regs->ecx,
> - (uint32_t)regs->edx,
> - (uint32_t)regs->esi,
> - (uint32_t)regs->edi,
> - (uint32_t)regs->ebp);
> + ebx, ecx, edx, esi, edi, ebp);
> +
> +#ifndef NDEBUG
> + /* Deliberately corrupt parameter regs not used by this hypercall. */
> + switch ( compat_hypercall_args_table[eax] )
> + {
> + case 0: ebx = 0xdeadf00d;
> + case 1: ecx = 0xdeadf00d;
> + case 2: edx = 0xdeadf00d;
> + case 3: esi = 0xdeadf00d;
> + case 4: edi = 0xdeadf00d;
> + case 5: ebp = 0xdeadf00d;
> + }
> +#endif
> +
> + regs->_eax = hvm_hypercall32_table[eax](ebx, ecx, edx, esi, edi,
> ebp);
> +
> +#ifndef NDEBUG
> + if ( !curr->arch.hvm_vcpu.hcall_preempted )
> + {
> + /* Deliberately corrupt parameter regs used by this hypercall. */
> + switch ( compat_hypercall_args_table[eax] )
> + {
> + case 6: regs->ebp = 0xdeadf00d;
> + case 5: regs->edi = 0xdeadf00d;
> + case 4: regs->esi = 0xdeadf00d;
> + case 3: regs->edx = 0xdeadf00d;
> + case 2: regs->ecx = 0xdeadf00d;
> + case 1: regs->ebx = 0xdeadf00d;
> + }
> + }
> +#endif
> }
>
> HVM_DBG_LOG(DBG_LEVEL_HCALL, "hcall%u -> %lx",
>
>
>
>
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