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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] x86-64: emulation support for cmpxchg16b
Thanks, I forgot about this one. Actually I will rework it so we only have
one cmpxchg() handling callback which takes pointers to old/new values and a
size up to 16 bytes.
-- Keir
On 21/4/08 17:35, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
> With the x86 instruction emulator no pretty complete, I'd like to
> re-submit this patch to support cmpxchg16b on x86-64 and at once rename
> the underlying emulator callback function pointer (making clear that if
> implemented, it is to operate on two longs rather than two 32-bit
> values). At the same time it fixes an apparently wrong emulator context
> initialization in the shadow code.
>
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>
> Index: 2008-04-15/tools/tests/test_x86_emulator.c
> ===================================================================
> --- 2008-04-15.orig/tools/tests/test_x86_emulator.c 2008-04-01
> 11:10:21.000000000 +0200
> +++ 2008-04-15/tools/tests/test_x86_emulator.c 2008-04-15 08:48:15.000000000
> +0200
> @@ -74,7 +74,7 @@ static int cmpxchg(
> return X86EMUL_OKAY;
> }
>
> -static int cmpxchg8b(
> +static int cmpxchg2(
> unsigned int seg,
> unsigned long offset,
> unsigned long old_lo,
> @@ -94,7 +94,7 @@ static struct x86_emulate_ops emulops =
> .insn_fetch = read,
> .write = write,
> .cmpxchg = cmpxchg,
> - .cmpxchg8b = cmpxchg8b
> + .cmpxchg2 = cmpxchg2
> };
>
> int main(int argc, char **argv)
> Index: 2008-04-15/tools/tests/x86_emulate.c
> ===================================================================
> --- 2008-04-15.orig/tools/tests/x86_emulate.c 2008-04-01 11:10:21.000000000
> +0200
> +++ 2008-04-15/tools/tests/x86_emulate.c 2008-04-15 08:48:15.000000000 +0200
> @@ -3,6 +3,8 @@
> #include <string.h>
> #include <public/xen.h>
>
> +#define cpu_has_cmpxchg16b (sizeof(long) == 8)
> +
> #include "x86_emulate/x86_emulate.h"
>
> #define __emulate_fpu_insn(_op) \
> Index: 2008-04-15/xen/arch/x86/mm.c
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/mm.c 2008-04-11 14:48:16.000000000 +0200
> +++ 2008-04-15/xen/arch/x86/mm.c 2008-04-15 08:48:15.000000000 +0200
> @@ -3635,6 +3635,7 @@ static int ptwr_emulated_cmpxchg(
> container_of(ctxt, struct ptwr_emulate_ctxt, ctxt));
> }
>
> +#ifdef __i386__
> static int ptwr_emulated_cmpxchg8b(
> enum x86_segment seg,
> unsigned long offset,
> @@ -3650,13 +3651,16 @@ static int ptwr_emulated_cmpxchg8b(
> offset, ((u64)old_hi << 32) | old, ((u64)new_hi << 32) | new, 8, 1,
> container_of(ctxt, struct ptwr_emulate_ctxt, ctxt));
> }
> +#else
> +#define ptwr_emulated_cmpxchg8b NULL
> +#endif
>
> static struct x86_emulate_ops ptwr_emulate_ops = {
> .read = ptwr_emulated_read,
> .insn_fetch = ptwr_emulated_read,
> .write = ptwr_emulated_write,
> .cmpxchg = ptwr_emulated_cmpxchg,
> - .cmpxchg8b = ptwr_emulated_cmpxchg8b
> + .cmpxchg2 = ptwr_emulated_cmpxchg8b
> };
>
> /* Write page fault handler: check if guest is trying to modify a PTE. */
> Index: 2008-04-15/xen/arch/x86/mm/shadow/common.c
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/mm/shadow/common.c 2008-04-11
> 14:48:16.000000000 +0200
> +++ 2008-04-15/xen/arch/x86/mm/shadow/common.c 2008-04-15 08:48:15.000000000
> +0200
> @@ -262,6 +262,7 @@ hvm_emulate_cmpxchg(enum x86_segment seg
> v, addr, old, new, bytes, sh_ctxt);
> }
>
> +#ifdef __i386__
> static int
> hvm_emulate_cmpxchg8b(enum x86_segment seg,
> unsigned long offset,
> @@ -288,13 +289,16 @@ hvm_emulate_cmpxchg8b(enum x86_segment s
> return v->arch.paging.mode->shadow.x86_emulate_cmpxchg8b(
> v, addr, old_lo, old_hi, new_lo, new_hi, sh_ctxt);
> }
> +#else
> +#define hvm_emulate_cmpxchg8b NULL
> +#endif
>
> static struct x86_emulate_ops hvm_shadow_emulator_ops = {
> .read = hvm_emulate_read,
> .insn_fetch = hvm_emulate_insn_fetch,
> .write = hvm_emulate_write,
> .cmpxchg = hvm_emulate_cmpxchg,
> - .cmpxchg8b = hvm_emulate_cmpxchg8b,
> + .cmpxchg2 = hvm_emulate_cmpxchg8b,
> };
>
> static int
> @@ -352,6 +356,7 @@ pv_emulate_cmpxchg(enum x86_segment seg,
> v, offset, old, new, bytes, sh_ctxt);
> }
>
> +#ifdef __i386__
> static int
> pv_emulate_cmpxchg8b(enum x86_segment seg,
> unsigned long offset,
> @@ -369,13 +374,16 @@ pv_emulate_cmpxchg8b(enum x86_segment se
> return v->arch.paging.mode->shadow.x86_emulate_cmpxchg8b(
> v, offset, old_lo, old_hi, new_lo, new_hi, sh_ctxt);
> }
> +#else
> +#define pv_emulate_cmpxchg8b NULL
> +#endif
>
> static struct x86_emulate_ops pv_shadow_emulator_ops = {
> .read = pv_emulate_read,
> .insn_fetch = pv_emulate_read,
> .write = pv_emulate_write,
> .cmpxchg = pv_emulate_cmpxchg,
> - .cmpxchg8b = pv_emulate_cmpxchg8b,
> + .cmpxchg2 = pv_emulate_cmpxchg8b,
> };
>
> struct x86_emulate_ops *shadow_init_emulation(
> @@ -390,7 +398,12 @@ struct x86_emulate_ops *shadow_init_emul
>
> if ( !is_hvm_vcpu(v) )
> {
> +#ifndef CONFIG_COMPAT
> sh_ctxt->ctxt.addr_size = sh_ctxt->ctxt.sp_size = BITS_PER_LONG;
> +#else
> + sh_ctxt->ctxt.addr_size = sh_ctxt->ctxt.sp_size =
> + !is_pv_32on64_vcpu(v) ? BITS_PER_LONG : COMPAT_BITS_PER_LONG;
> +#endif
> return &pv_shadow_emulator_ops;
> }
>
> Index: 2008-04-15/xen/arch/x86/mm/shadow/multi.c
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/mm/shadow/multi.c 2008-04-01
> 14:20:52.000000000 +0200
> +++ 2008-04-15/xen/arch/x86/mm/shadow/multi.c 2008-04-15 08:48:15.000000000
> +0200
> @@ -4432,7 +4432,8 @@ sh_x86_emulate_cmpxchg(struct vcpu *v, u
> return rv;
> }
>
> -int
> +#ifdef __i386__
> +static int
> sh_x86_emulate_cmpxchg8b(struct vcpu *v, unsigned long vaddr,
> unsigned long old_lo, unsigned long old_hi,
> unsigned long new_lo, unsigned long new_hi,
> @@ -4465,6 +4466,7 @@ sh_x86_emulate_cmpxchg8b(struct vcpu *v,
> shadow_unlock(v->domain);
> return rv;
> }
> +#endif
>
>
> /**************************************************************************/
> @@ -4738,7 +4740,9 @@ struct paging_mode sh_paging_mode = {
> .shadow.detach_old_tables = sh_detach_old_tables,
> .shadow.x86_emulate_write = sh_x86_emulate_write,
> .shadow.x86_emulate_cmpxchg = sh_x86_emulate_cmpxchg,
> +#ifdef __i386__
> .shadow.x86_emulate_cmpxchg8b = sh_x86_emulate_cmpxchg8b,
> +#endif
> .shadow.make_monitor_table = sh_make_monitor_table,
> .shadow.destroy_monitor_table = sh_destroy_monitor_table,
> #if SHADOW_OPTIMIZATIONS & SHOPT_WRITABLE_HEURISTIC
> Index: 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.c
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/x86_emulate/x86_emulate.c 2008-04-01
> 11:10:21.000000000 +0200
> +++ 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.c 2008-04-15
> 08:48:15.000000000 +0200
> @@ -3346,60 +3346,64 @@ x86_emulate(
> src.val = x86_seg_gs;
> goto pop_seg;
>
> - case 0xc7: /* Grp9 (cmpxchg8b) */
> -#if defined(__i386__)
> - {
> - unsigned long old_lo, old_hi;
> + case 0xc7: /* Grp9 (cmpxchg{8,16}b) */
> generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1);
> generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
> - if ( (rc = ops->read(ea.mem.seg, ea.mem.off+0, &old_lo, 4, ctxt)) ||
> - (rc = ops->read(ea.mem.seg, ea.mem.off+4, &old_hi, 4, ctxt)) )
> - goto done;
> - if ( (old_lo != _regs.eax) || (old_hi != _regs.edx) )
> - {
> - _regs.eax = old_lo;
> - _regs.edx = old_hi;
> - _regs.eflags &= ~EFLG_ZF;
> - }
> - else if ( ops->cmpxchg8b == NULL )
> - {
> - rc = X86EMUL_UNHANDLEABLE;
> - goto done;
> - }
> - else
> +#ifdef __x86_64__
> + if ( op_bytes != 8 )
> {
> - if ( (rc = ops->cmpxchg8b(ea.mem.seg, ea.mem.off, old_lo, old_hi,
> - _regs.ebx, _regs.ecx, ctxt)) != 0 )
> + unsigned long old, new;
> +
> + if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &old, 8, ctxt)) != 0
> )
> goto done;
> - _regs.eflags |= EFLG_ZF;
> - }
> - break;
> - }
> -#elif defined(__x86_64__)
> - {
> - unsigned long old, new;
> - generate_exception_if((modrm_reg & 7) != 1, EXC_UD, -1);
> - generate_exception_if(ea.type != OP_MEM, EXC_UD, -1);
> - if ( (rc = ops->read(ea.mem.seg, ea.mem.off, &old, 8, ctxt)) != 0 )
> - goto done;
> - if ( ((uint32_t)(old>>0) != (uint32_t)_regs.eax) ||
> - ((uint32_t)(old>>32) != (uint32_t)_regs.edx) )
> - {
> - _regs.eax = (uint32_t)(old>>0);
> - _regs.edx = (uint32_t)(old>>32);
> - _regs.eflags &= ~EFLG_ZF;
> + if ( ((uint32_t)(old>>0) != (uint32_t)_regs.eax) ||
> + ((uint32_t)(old>>32) != (uint32_t)_regs.edx) )
> + {
> + _regs.eax = (uint32_t)(old>>0);
> + _regs.edx = (uint32_t)(old>>32);
> + _regs.eflags &= ~EFLG_ZF;
> + }
> + else
> + {
> + new = (_regs.ecx<<32)|(uint32_t)_regs.ebx;
> + if ( (rc = ops->cmpxchg(ea.mem.seg, ea.mem.off, old,
> + new, 8, ctxt)) != 0 )
> + goto done;
> + _regs.eflags |= EFLG_ZF;
> + }
> }
> + else if ( !cpu_has_cmpxchg16b )
> + generate_exception_if(1, EXC_UD, -1);
> else
> +#endif
> {
> - new = (_regs.ecx<<32)|(uint32_t)_regs.ebx;
> - if ( (rc = ops->cmpxchg(ea.mem.seg, ea.mem.off, old,
> - new, 8, ctxt)) != 0 )
> + unsigned long old_lo, old_hi;
> +
> + if ( (rc = ops->read(ea.mem.seg, ea.mem.off,
> + &old_lo, sizeof(old_lo), ctxt)) ||
> + (rc = ops->read(ea.mem.seg, ea.mem.off+sizeof(old_lo),
> + &old_hi, sizeof(old_lo), ctxt)) )
> + goto done;
> + if ( (old_lo != _regs.eax) || (old_hi != _regs.edx) )
> + {
> + _regs.eax = old_lo;
> + _regs.edx = old_hi;
> + _regs.eflags &= ~EFLG_ZF;
> + }
> + else if ( ops->cmpxchg2 == NULL )
> + {
> + rc = X86EMUL_UNHANDLEABLE;
> goto done;
> - _regs.eflags |= EFLG_ZF;
> + }
> + else
> + {
> + if ( (rc = ops->cmpxchg2(ea.mem.seg, ea.mem.off, old_lo,
> old_hi,
> + _regs.ebx, _regs.ecx, ctxt)) != 0 )
> + goto done;
> + _regs.eflags |= EFLG_ZF;
> + }
> }
> break;
> - }
> -#endif
>
> case 0xc8 ... 0xcf: /* bswap */
> dst.type = OP_REG;
> @@ -3409,7 +3413,7 @@ x86_emulate(
> {
> default: /* case 2: */
> /* Undefined behaviour. Writes zero on all tested CPUs. */
> - dst.val = 0;
> + __asm__("data16 bswap %k0" : "+r" (dst.val));
> break;
> case 4:
> #ifdef __x86_64__
> Index: 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.h
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/x86_emulate/x86_emulate.h 2008-04-01
> 11:10:21.000000000 +0200
> +++ 2008-04-15/xen/arch/x86/x86_emulate/x86_emulate.h 2008-04-15
> 08:48:15.000000000 +0200
> @@ -104,8 +104,9 @@ struct segment_register {
> * some out-of-band mechanism, unknown to the emulator. The memop signals
> * failure by returning X86EMUL_EXCEPTION to the emulator, which will
> * then immediately bail.
> - * 2. Valid access sizes are 1, 2, 4 and 8 bytes. On x86/32 systems only
> - * cmpxchg8b_emulated need support 8-byte accesses.
> + * 2. Valid access sizes are 1, 2, 4, 8, and 16 bytes. On x86/32 systems
> only
> + * cmpxchg2_emulated need support 8-byte accesses. On x86/64 systems only
> + * cmpxchg2_emulated need support 16-byte accesses.
> * 3. The emulator cannot handle 64-bit mode emulation on an x86/32 system.
> */
> struct x86_emulate_ops
> @@ -165,16 +166,17 @@ struct x86_emulate_ops
> struct x86_emulate_ctxt *ctxt);
>
> /*
> - * cmpxchg8b: Emulate an atomic (LOCKed) CMPXCHG8B operation.
> + * cmpxchg2: Emulate an atomic (LOCKed) CMPXCHG{8,16}B operation.
> * @old: [IN ] Value expected to be current at @addr.
> * @new: [IN ] Value to write to @addr.
> * NOTES:
> - * 1. This function is only ever called when emulating a real CMPXCHG8B.
> - * 2. This function is *never* called on x86/64 systems.
> - * 2. Not defining this function (i.e., specifying NULL) is equivalent
> + * 1. This function is only ever called when emulating a real
> CMPXCHG{8,16}B.
> + * 2. This function is *never* called on x86/64 systems for emulating
> + * CMPXCHG8B.
> + * 3. Not defining this function (i.e., specifying NULL) is equivalent
> * to defining a function that always returns X86EMUL_UNHANDLEABLE.
> */
> - int (*cmpxchg8b)(
> + int (*cmpxchg2)(
> enum x86_segment seg,
> unsigned long offset,
> unsigned long old_lo,
> Index: 2008-04-15/xen/arch/x86/x86_emulate.c
> ===================================================================
> --- 2008-04-15.orig/xen/arch/x86/x86_emulate.c 2008-04-01 14:20:52.000000000
> +0200
> +++ 2008-04-15/xen/arch/x86/x86_emulate.c 2008-04-15 08:48:15.000000000 +0200
> @@ -12,6 +12,8 @@
> #include <asm/x86_emulate.h>
>
> #undef cmpxchg
> +#undef cpuid
> +#undef wbinvd
>
> #define __emulate_fpu_insn(_op) \
> do{ int _exn; \
> Index: 2008-04-15/xen/include/asm-x86/cpufeature.h
> ===================================================================
> --- 2008-04-15.orig/xen/include/asm-x86/cpufeature.h 2008-04-01
> 14:20:52.000000000 +0200
> +++ 2008-04-15/xen/include/asm-x86/cpufeature.h 2008-04-15 08:48:15.000000000
> +0200
> @@ -149,6 +149,7 @@
> #define cpu_has_cyrix_arr boot_cpu_has(X86_FEATURE_CYRIX_ARR)
> #define cpu_has_centaur_mcr boot_cpu_has(X86_FEATURE_CENTAUR_MCR)
> #define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
> +#define cpu_has_cmpxchg16b 0
> #define cpu_has_page1gb 0
> #define cpu_has_efer (boot_cpu_data.x86_capability[1] & 0x20100800)
> #else /* __x86_64__ */
> @@ -175,6 +176,7 @@
> #define cpu_has_cyrix_arr 0
> #define cpu_has_centaur_mcr 0
> #define cpu_has_clflush boot_cpu_has(X86_FEATURE_CLFLSH)
> +#define cpu_has_cmpxchg16b boot_cpu_has(X86_FEATURE_CX16)
> #define cpu_has_page1gb boot_cpu_has(X86_FEATURE_PAGE1GB)
> #define cpu_has_efer 1
> #endif
> Index: 2008-04-15/xen/include/asm-x86/paging.h
> ===================================================================
> --- 2008-04-15.orig/xen/include/asm-x86/paging.h 2008-04-11 14:48:16.000000000
> +0200
> +++ 2008-04-15/xen/include/asm-x86/paging.h 2008-04-15 08:48:15.000000000
> +0200
> @@ -83,12 +83,14 @@ struct shadow_paging_mode {
> unsigned long new,
> unsigned int bytes,
> struct sh_emulate_ctxt *sh_ctxt);
> +#ifdef __i386__
> int (*x86_emulate_cmpxchg8b )(struct vcpu *v, unsigned long va,
> unsigned long old_lo,
> unsigned long old_hi,
> unsigned long new_lo,
> unsigned long new_hi,
> struct sh_emulate_ctxt *sh_ctxt);
> +#endif
> mfn_t (*make_monitor_table )(struct vcpu *v);
> void (*destroy_monitor_table )(struct vcpu *v, mfn_t mmfn);
> int (*guess_wrmap )(struct vcpu *v,
> Index: 2008-04-15/xen/include/asm-x86/x86_emulate.h
> ===================================================================
> --- 2008-04-15.orig/xen/include/asm-x86/x86_emulate.h 2008-04-01
> 14:20:52.000000000 +0200
> +++ 2008-04-15/xen/include/asm-x86/x86_emulate.h 2008-04-15 08:48:15.000000000
> +0200
> @@ -16,6 +16,7 @@
> #include <xen/types.h>
> #include <xen/lib.h>
> #include <asm/regs.h>
> +#include <asm/processor.h>
>
> #include "../../arch/x86/x86_emulate/x86_emulate.h"
>
>
>
>
> _______________________________________________
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