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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] x86emul: support FNSTENV and FNSAVE
commit 422a104ba3c84795a08fa107117d6d08e79ef106
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Fri May 29 17:33:54 2020 +0200
Commit: Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Fri May 29 17:33:54 2020 +0200
x86emul: support FNSTENV and FNSAVE
To avoid introducing another boolean into emulator state, the
rex_prefix field gets (ab)used to convey the real/VM86 vs protected mode
info (affecting structure layout, albeit not size) to x86_emul_blk().
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
tools/tests/x86_emulator/test_x86_emulator.c | 75 +++++++++++
tools/tests/x86_emulator/x86-emulate.h | 1 +
xen/arch/x86/x86_emulate/x86_emulate.c | 181 ++++++++++++++++++++++++++-
3 files changed, 254 insertions(+), 3 deletions(-)
diff --git a/tools/tests/x86_emulator/test_x86_emulator.c
b/tools/tests/x86_emulator/test_x86_emulator.c
index c80cb58d7d..ae8f140aa8 100644
--- a/tools/tests/x86_emulator/test_x86_emulator.c
+++ b/tools/tests/x86_emulator/test_x86_emulator.c
@@ -748,6 +748,25 @@ static struct x86_emulate_ops emulops = {
#define MMAP_ADDR 0x100000
+/*
+ * 64-bit OSes may not (be able to) properly restore the two selectors in
+ * the FPU environment. Zap them so that memcmp() on two saved images will
+ * work regardless of whether a context switch occurred in the middle.
+ */
+static void zap_fpsel(unsigned int *env, bool is_32bit)
+{
+ if ( is_32bit )
+ {
+ env[4] &= ~0xffff;
+ env[6] &= ~0xffff;
+ }
+ else
+ {
+ env[2] &= ~0xffff;
+ env[3] &= ~0xffff;
+ }
+}
+
#ifdef __x86_64__
# define STKVAL_DISP 64
static const struct {
@@ -2396,6 +2415,62 @@ int main(int argc, char **argv)
else
printf("skipped\n");
+ printf("%-40s", "Testing fnstenv 4(%ecx)...");
+ if ( stack_exec && cpu_has_fpu )
+ {
+ const uint16_t three = 3;
+
+ asm volatile ( "fninit\n\t"
+ "fld1\n\t"
+ "fidivs %1\n\t"
+ "fstenv %0"
+ : "=m" (res[9]) : "m" (three) : "memory" );
+ zap_fpsel(&res[9], true);
+ instr[0] = 0xd9; instr[1] = 0x71; instr[2] = 0x04;
+ regs.eip = (unsigned long)&instr[0];
+ regs.ecx = (unsigned long)res;
+ res[8] = 0xaa55aa55;
+ rc = x86_emulate(&ctxt, &emulops);
+ zap_fpsel(&res[1], true);
+ if ( (rc != X86EMUL_OKAY) ||
+ memcmp(res + 1, res + 9, 28) ||
+ res[8] != 0xaa55aa55 ||
+ (regs.eip != (unsigned long)&instr[3]) )
+ goto fail;
+ printf("okay\n");
+ }
+ else
+ printf("skipped\n");
+
+ printf("%-40s", "Testing 16-bit fnsave (%ecx)...");
+ if ( stack_exec && cpu_has_fpu )
+ {
+ const uint16_t five = 5;
+
+ asm volatile ( "fninit\n\t"
+ "fld1\n\t"
+ "fidivs %1\n\t"
+ "fsaves %0"
+ : "=m" (res[25]) : "m" (five) : "memory" );
+ zap_fpsel(&res[25], false);
+ asm volatile ( "frstors %0" :: "m" (res[25]) : "memory" );
+ instr[0] = 0x66; instr[1] = 0xdd; instr[2] = 0x31;
+ regs.eip = (unsigned long)&instr[0];
+ regs.ecx = (unsigned long)res;
+ res[23] = 0xaa55aa55;
+ res[24] = 0xaa55aa55;
+ rc = x86_emulate(&ctxt, &emulops);
+ if ( (rc != X86EMUL_OKAY) ||
+ memcmp(res, res + 25, 94) ||
+ (res[23] >> 16) != 0xaa55 ||
+ res[24] != 0xaa55aa55 ||
+ (regs.eip != (unsigned long)&instr[3]) )
+ goto fail;
+ printf("okay\n");
+ }
+ else
+ printf("skipped\n");
+
printf("%-40s", "Testing movq %mm3,(%ecx)...");
if ( stack_exec && cpu_has_mmx )
{
diff --git a/tools/tests/x86_emulator/x86-emulate.h
b/tools/tests/x86_emulator/x86-emulate.h
index 978dc48b33..6ea6cbc658 100644
--- a/tools/tests/x86_emulator/x86-emulate.h
+++ b/tools/tests/x86_emulator/x86-emulate.h
@@ -129,6 +129,7 @@ static inline bool xcr0_mask(uint64_t mask)
}
#define cache_line_size() (cp.basic.clflush_size * 8)
+#define cpu_has_fpu cp.basic.fpu
#define cpu_has_mmx cp.basic.mmx
#define cpu_has_fxsr cp.basic.fxsr
#define cpu_has_sse cp.basic.sse
diff --git a/xen/arch/x86/x86_emulate/x86_emulate.c
b/xen/arch/x86/x86_emulate/x86_emulate.c
index 505ec09662..5ecf5c6335 100644
--- a/xen/arch/x86/x86_emulate/x86_emulate.c
+++ b/xen/arch/x86/x86_emulate/x86_emulate.c
@@ -856,6 +856,9 @@ struct x86_emulate_state {
enum {
blk_NONE,
blk_enqcmd,
+#ifndef X86EMUL_NO_FPU
+ blk_fst, /* FNSTENV, FNSAVE */
+#endif
blk_movdir,
} blk;
uint8_t modrm, modrm_mod, modrm_reg, modrm_rm;
@@ -897,6 +900,50 @@ struct x86_emulate_state {
#define PTR_POISON NULL /* 32-bit builds are for user-space, so NULL is OK. */
#endif
+#ifndef X86EMUL_NO_FPU
+struct x87_env16 {
+ uint16_t fcw;
+ uint16_t fsw;
+ uint16_t ftw;
+ union {
+ struct {
+ uint16_t fip_lo;
+ uint16_t fop:11, :1, fip_hi:4;
+ uint16_t fdp_lo;
+ uint16_t :12, fdp_hi:4;
+ } real;
+ struct {
+ uint16_t fip;
+ uint16_t fcs;
+ uint16_t fdp;
+ uint16_t fds;
+ } prot;
+ } mode;
+};
+
+struct x87_env32 {
+ uint32_t fcw:16, :16;
+ uint32_t fsw:16, :16;
+ uint32_t ftw:16, :16;
+ union {
+ struct {
+ /* some CPUs/FPUs also store the full FIP here */
+ uint32_t fip_lo:16, :16;
+ uint32_t fop:11, :1, fip_hi:16, :4;
+ /* some CPUs/FPUs also store the full FDP here */
+ uint32_t fdp_lo:16, :16;
+ uint32_t :12, fdp_hi:16, :4;
+ } real;
+ struct {
+ uint32_t fip;
+ uint32_t fcs:16, fop:11, :5;
+ uint32_t fdp;
+ uint32_t fds:16, :16;
+ } prot;
+ } mode;
+};
+#endif
+
typedef union {
uint64_t mmx;
uint64_t __attribute__ ((aligned(16))) xmm[2];
@@ -4924,9 +4971,22 @@ x86_emulate(
goto done;
emulate_fpu_insn_memsrc(b, modrm_reg & 7, src.val);
break;
- case 6: /* fnstenv - TODO */
+ case 6: /* fnstenv */
+ fail_if(!ops->blk);
+ state->blk = blk_fst;
+ /*
+ * REX is meaningless for this insn by this point - (ab)use
+ * the field to communicate real vs protected mode to ->blk().
+ */
+ /*state->*/rex_prefix = in_protmode(ctxt, ops);
+ if ( (rc = ops->blk(ea.mem.seg, ea.mem.off, NULL,
+ op_bytes > 2 ? sizeof(struct x87_env32)
+ : sizeof(struct x87_env16),
+ &_regs.eflags,
+ state, ctxt)) != X86EMUL_OKAY )
+ goto done;
state->fpu_ctrl = true;
- goto unimplemented_insn;
+ break;
case 7: /* fnstcw m2byte */
state->fpu_ctrl = true;
fpu_memdst16:
@@ -5080,9 +5140,24 @@ x86_emulate(
emulate_fpu_insn_memdst(b, modrm_reg & 7, dst.val);
break;
case 4: /* frstor - TODO */
- case 6: /* fnsave - TODO */
state->fpu_ctrl = true;
goto unimplemented_insn;
+ case 6: /* fnsave */
+ fail_if(!ops->blk);
+ state->blk = blk_fst;
+ /*
+ * REX is meaningless for this insn by this point - (ab)use
+ * the field to communicate real vs protected mode to ->blk().
+ */
+ /*state->*/rex_prefix = in_protmode(ctxt, ops);
+ if ( (rc = ops->blk(ea.mem.seg, ea.mem.off, NULL,
+ op_bytes > 2 ? sizeof(struct x87_env32) +
80
+ : sizeof(struct x87_env16) +
80,
+ &_regs.eflags,
+ state, ctxt)) != X86EMUL_OKAY )
+ goto done;
+ state->fpu_ctrl = true;
+ break;
case 7: /* fnstsw m2byte */
state->fpu_ctrl = true;
goto fpu_memdst16;
@@ -11559,6 +11634,14 @@ int x86_emul_blk(
switch ( state->blk )
{
bool zf;
+#ifndef X86EMUL_NO_FPU
+ struct {
+ struct x87_env32 env;
+ struct {
+ uint8_t bytes[10];
+ } freg[8];
+ } fpstate;
+#endif
/*
* Throughout this switch(), memory clobbers are used to compensate
@@ -11588,6 +11671,98 @@ int x86_emul_blk(
*eflags |= X86_EFLAGS_ZF;
break;
+#ifndef X86EMUL_NO_FPU
+
+ case blk_fst:
+ ASSERT(!data);
+
+ /* Don't chance consuming uninitialized data. */
+ memset(&fpstate, 0, sizeof(fpstate));
+ if ( bytes > sizeof(fpstate.env) )
+ asm ( "fnsave %0" : "+m" (fpstate) );
+ else
+ asm ( "fnstenv %0" : "+m" (fpstate.env) );
+
+ /* state->rex_prefix carries CR0.PE && !EFLAGS.VM setting */
+ switch ( bytes )
+ {
+ case sizeof(fpstate.env): /* 32-bit FNSTENV */
+ case sizeof(fpstate): /* 32-bit FNSAVE */
+ if ( !state->rex_prefix )
+ {
+ /* Convert 32-bit prot to 32-bit real/vm86 format. */
+ unsigned int fip = fpstate.env.mode.prot.fip +
+ (fpstate.env.mode.prot.fcs << 4);
+ unsigned int fdp = fpstate.env.mode.prot.fdp +
+ (fpstate.env.mode.prot.fds << 4);
+ unsigned int fop = fpstate.env.mode.prot.fop;
+
+ memset(&fpstate.env.mode, 0, sizeof(fpstate.env.mode));
+ fpstate.env.mode.real.fip_lo = fip;
+ fpstate.env.mode.real.fip_hi = fip >> 16;
+ fpstate.env.mode.real.fop = fop;
+ fpstate.env.mode.real.fdp_lo = fdp;
+ fpstate.env.mode.real.fdp_hi = fdp >> 16;
+ }
+ memcpy(ptr, &fpstate.env, sizeof(fpstate.env));
+ if ( bytes == sizeof(fpstate.env) )
+ ptr = NULL;
+ else
+ ptr += sizeof(fpstate.env);
+ break;
+
+ case sizeof(struct x87_env16): /* 16-bit
FNSTENV */
+ case sizeof(struct x87_env16) + sizeof(fpstate.freg): /* 16-bit FNSAVE
*/
+ if ( state->rex_prefix )
+ {
+ /* Convert 32-bit prot to 16-bit prot format. */
+ struct x87_env16 *env = ptr;
+
+ env->fcw = fpstate.env.fcw;
+ env->fsw = fpstate.env.fsw;
+ env->ftw = fpstate.env.ftw;
+ env->mode.prot.fip = fpstate.env.mode.prot.fip;
+ env->mode.prot.fcs = fpstate.env.mode.prot.fcs;
+ env->mode.prot.fdp = fpstate.env.mode.prot.fdp;
+ env->mode.prot.fds = fpstate.env.mode.prot.fds;
+ }
+ else
+ {
+ /* Convert 32-bit prot to 16-bit real/vm86 format. */
+ unsigned int fip = fpstate.env.mode.prot.fip +
+ (fpstate.env.mode.prot.fcs << 4);
+ unsigned int fdp = fpstate.env.mode.prot.fdp +
+ (fpstate.env.mode.prot.fds << 4);
+ struct x87_env16 env = {
+ .fcw = fpstate.env.fcw,
+ .fsw = fpstate.env.fsw,
+ .ftw = fpstate.env.ftw,
+ .mode.real.fip_lo = fip,
+ .mode.real.fip_hi = fip >> 16,
+ .mode.real.fop = fpstate.env.mode.prot.fop,
+ .mode.real.fdp_lo = fdp,
+ .mode.real.fdp_hi = fdp >> 16
+ };
+
+ memcpy(ptr, &env, sizeof(env));
+ }
+ if ( bytes == sizeof(struct x87_env16) )
+ ptr = NULL;
+ else
+ ptr += sizeof(struct x87_env16);
+ break;
+
+ default:
+ ASSERT_UNREACHABLE();
+ return X86EMUL_UNHANDLEABLE;
+ }
+
+ if ( ptr )
+ memcpy(ptr, fpstate.freg, sizeof(fpstate.freg));
+ break;
+
+#endif /* X86EMUL_NO_FPU */
+
case blk_movdir:
switch ( bytes )
{
--
generated by git-patchbot for /home/xen/git/xen.git#master
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