diff options
| -rw-r--r-- | include/asm-x86/xen/hypercall.h | 170 |
1 files changed, 122 insertions, 48 deletions
diff --git a/include/asm-x86/xen/hypercall.h b/include/asm-x86/xen/hypercall.h index 0551b9d82ec..d0c5dedcb00 100644 --- a/include/asm-x86/xen/hypercall.h +++ b/include/asm-x86/xen/hypercall.h @@ -40,83 +40,157 @@ #include <xen/interface/sched.h> #include <xen/interface/physdev.h> +/* + * The hypercall asms have to meet several constraints: + * - Work on 32- and 64-bit. + * The two architectures put their arguments in different sets of + * registers. + * + * - Work around asm syntax quirks + * It isn't possible to specify one of the rNN registers in a + * constraint, so we use explicit register variables to get the + * args into the right place. + * + * - Mark all registers as potentially clobbered + * Even unused parameters can be clobbered by the hypervisor, so we + * need to make sure gcc knows it. + * + * - Avoid compiler bugs. + * This is the tricky part. Because x86_32 has such a constrained + * register set, gcc versions below 4.3 have trouble generating + * code when all the arg registers and memory are trashed by the + * asm. There are syntactically simpler ways of achieving the + * semantics below, but they cause the compiler to crash. + * + * The only combination I found which works is: + * - assign the __argX variables first + * - list all actually used parameters as "+r" (__argX) + * - clobber the rest + * + * The result certainly isn't pretty, and it really shows up cpp's + * weakness as as macro language. Sorry. (But let's just give thanks + * there aren't more than 5 arguments...) + */ + extern struct { char _entry[32]; } hypercall_page[]; +#define __HYPERCALL "call hypercall_page+%c[offset]" +#define __HYPERCALL_ENTRY(x) \ + [offset] "i" (__HYPERVISOR_##x * sizeof(hypercall_page[0])) + +#ifdef CONFIG_X86_32 +#define __HYPERCALL_RETREG "eax" +#define __HYPERCALL_ARG1REG "ebx" +#define __HYPERCALL_ARG2REG "ecx" +#define __HYPERCALL_ARG3REG "edx" +#define __HYPERCALL_ARG4REG "esi" +#define __HYPERCALL_ARG5REG "edi" +#else +#define __HYPERCALL_RETREG "rax" +#define __HYPERCALL_ARG1REG "rdi" +#define __HYPERCALL_ARG2REG "rsi" +#define __HYPERCALL_ARG3REG "rdx" +#define __HYPERCALL_ARG4REG "r10" +#define __HYPERCALL_ARG5REG "r8" +#endif + +#define __HYPERCALL_DECLS \ + register unsigned long __res asm(__HYPERCALL_RETREG); \ + register unsigned long __arg1 asm(__HYPERCALL_ARG1REG) = __arg1; \ + register unsigned long __arg2 asm(__HYPERCALL_ARG2REG) = __arg2; \ + register unsigned long __arg3 asm(__HYPERCALL_ARG3REG) = __arg3; \ + register unsigned long __arg4 asm(__HYPERCALL_ARG4REG) = __arg4; \ + register unsigned long __arg5 asm(__HYPERCALL_ARG5REG) = __arg5; + +#define __HYPERCALL_0PARAM "=r" (__res) +#define __HYPERCALL_1PARAM __HYPERCALL_0PARAM, "+r" (__arg1) +#define __HYPERCALL_2PARAM __HYPERCALL_1PARAM, "+r" (__arg2) +#define __HYPERCALL_3PARAM __HYPERCALL_2PARAM, "+r" (__arg3) +#define __HYPERCALL_4PARAM __HYPERCALL_3PARAM, "+r" (__arg4) +#define __HYPERCALL_5PARAM __HYPERCALL_4PARAM, "+r" (__arg5) + +#define __HYPERCALL_0ARG() +#define __HYPERCALL_1ARG(a1) \ + __HYPERCALL_0ARG() __arg1 = (unsigned long)(a1); +#define __HYPERCALL_2ARG(a1,a2) \ + __HYPERCALL_1ARG(a1) __arg2 = (unsigned long)(a2); +#define __HYPERCALL_3ARG(a1,a2,a3) \ + __HYPERCALL_2ARG(a1,a2) __arg3 = (unsigned long)(a3); +#define __HYPERCALL_4ARG(a1,a2,a3,a4) \ + __HYPERCALL_3ARG(a1,a2,a3) __arg4 = (unsigned long)(a4); +#define __HYPERCALL_5ARG(a1,a2,a3,a4,a5) \ + __HYPERCALL_4ARG(a1,a2,a3,a4) __arg5 = (unsigned long)(a5); + +#define __HYPERCALL_CLOBBER5 "memory" +#define __HYPERCALL_CLOBBER4 __HYPERCALL_CLOBBER5, __HYPERCALL_ARG5REG +#define __HYPERCALL_CLOBBER3 __HYPERCALL_CLOBBER4, __HYPERCALL_ARG4REG +#define __HYPERCALL_CLOBBER2 __HYPERCALL_CLOBBER3, __HYPERCALL_ARG3REG +#define __HYPERCALL_CLOBBER1 __HYPERCALL_CLOBBER2, __HYPERCALL_ARG2REG +#define __HYPERCALL_CLOBBER0 __HYPERCALL_CLOBBER1, __HYPERCALL_ARG1REG + #define _hypercall0(type, name) \ ({ \ - long __res; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res) \ - : [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_0ARG(); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_0PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER0); \ (type)__res; \ }) #define _hypercall1(type, name, a1) \ ({ \ - long __res, __ign1; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res), "=b" (__ign1) \ - : "1" ((long)(a1)), \ - [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_1ARG(a1); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_1PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER1); \ (type)__res; \ }) #define _hypercall2(type, name, a1, a2) \ ({ \ - long __res, __ign1, __ign2; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res), "=b" (__ign1), "=c" (__ign2) \ - : "1" ((long)(a1)), "2" ((long)(a2)), \ - [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_2ARG(a1, a2); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_2PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER2); \ (type)__res; \ }) #define _hypercall3(type, name, a1, a2, a3) \ ({ \ - long __res, __ign1, __ign2, __ign3; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res), "=b" (__ign1), "=c" (__ign2), \ - "=d" (__ign3) \ - : "1" ((long)(a1)), "2" ((long)(a2)), \ - "3" ((long)(a3)), \ - [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_3ARG(a1, a2, a3); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_3PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER3); \ (type)__res; \ }) #define _hypercall4(type, name, a1, a2, a3, a4) \ ({ \ - long __res, __ign1, __ign2, __ign3, __ign4; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res), "=b" (__ign1), "=c" (__ign2), \ - "=d" (__ign3), "=S" (__ign4) \ - : "1" ((long)(a1)), "2" ((long)(a2)), \ - "3" ((long)(a3)), "4" ((long)(a4)), \ - [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_4ARG(a1, a2, a3, a4); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_4PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER4); \ (type)__res; \ }) #define _hypercall5(type, name, a1, a2, a3, a4, a5) \ ({ \ - long __res, __ign1, __ign2, __ign3, __ign4, __ign5; \ - asm volatile ( \ - "call %[call]" \ - : "=a" (__res), "=b" (__ign1), "=c" (__ign2), \ - "=d" (__ign3), "=S" (__ign4), "=D" (__ign5) \ - : "1" ((long)(a1)), "2" ((long)(a2)), \ - "3" ((long)(a3)), "4" ((long)(a4)), \ - "5" ((long)(a5)), \ - [call] "m" (hypercall_page[__HYPERVISOR_##name]) \ - : "memory" ); \ + __HYPERCALL_DECLS; \ + __HYPERCALL_5ARG(a1, a2, a3, a4, a5); \ + asm volatile (__HYPERCALL \ + : __HYPERCALL_5PARAM \ + : __HYPERCALL_ENTRY(name) \ + : __HYPERCALL_CLOBBER5); \ (type)__res; \ }) |