[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-changelog] [xen master] x86/pv: Introduce and use x86emul_read_dr()
commit 881f8dc4314809293efc6f66f9af49734994bf0e Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Fri Mar 23 20:13:50 2018 +0000 Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CommitDate: Tue Apr 17 15:12:36 2018 +0100 x86/pv: Introduce and use x86emul_read_dr() do_get_debugreg() has several bugs: * The %cr4.de condition is inverted. %dr4/5 should be accessible only when %cr4.de is disabled. * When %cr4.de is disabled, emulation should yield #UD rather than complete with zero. * Using -EINVAL for errors is a broken ABI, as it overlaps with valid values near the top of the address space. Introduce a common x86emul_read_dr() handler (as we will eventually want to add HVM support) which separates its success/failure indication from the data value, and have do_get_debugreg() call into the handler. The ABI of do_get_debugreg() remains broken, but switches from -EINVAL to -ENODEV for compatibility with the changes in the following patch. Take the opportunity to add a missing local variable block to x86_emulate.c Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Acked-by: Jan Beulich <jbeulich@xxxxxxxx> Release-acked-by: Juergen Gross <jgross@xxxxxxxx> --- xen/arch/x86/pv/emul-priv-op.c | 15 +---------- xen/arch/x86/pv/misc-hypercalls.c | 18 +++---------- xen/arch/x86/x86_emulate.c | 49 ++++++++++++++++++++++++++++++++++ xen/arch/x86/x86_emulate/x86_emulate.h | 3 +++ 4 files changed, 56 insertions(+), 29 deletions(-) diff --git a/xen/arch/x86/pv/emul-priv-op.c b/xen/arch/x86/pv/emul-priv-op.c index b4564080ad..61702d9cd3 100644 --- a/xen/arch/x86/pv/emul-priv-op.c +++ b/xen/arch/x86/pv/emul-priv-op.c @@ -794,19 +794,6 @@ static int write_cr(unsigned int reg, unsigned long val, return X86EMUL_UNHANDLEABLE; } -static int read_dr(unsigned int reg, unsigned long *val, - struct x86_emulate_ctxt *ctxt) -{ - unsigned long res = do_get_debugreg(reg); - - if ( IS_ERR_VALUE(res) ) - return X86EMUL_UNHANDLEABLE; - - *val = res; - - return X86EMUL_OKAY; -} - static int write_dr(unsigned int reg, unsigned long val, struct x86_emulate_ctxt *ctxt) { @@ -1305,7 +1292,7 @@ static const struct x86_emulate_ops priv_op_ops = { .read_segment = read_segment, .read_cr = read_cr, .write_cr = write_cr, - .read_dr = read_dr, + .read_dr = x86emul_read_dr, .write_dr = write_dr, .write_xcr = x86emul_write_xcr, .read_msr = read_msr, diff --git a/xen/arch/x86/pv/misc-hypercalls.c b/xen/arch/x86/pv/misc-hypercalls.c index 5862130697..1619be7874 100644 --- a/xen/arch/x86/pv/misc-hypercalls.c +++ b/xen/arch/x86/pv/misc-hypercalls.c @@ -30,22 +30,10 @@ long do_set_debugreg(int reg, unsigned long value) unsigned long do_get_debugreg(int reg) { - struct vcpu *curr = current; + unsigned long val; + int res = x86emul_read_dr(reg, &val, NULL); - switch ( reg ) - { - case 0 ... 3: - case 6: - return curr->arch.debugreg[reg]; - case 7: - return (curr->arch.debugreg[7] | - curr->arch.debugreg[5]); - case 4 ... 5: - return ((curr->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) ? - curr->arch.debugreg[reg + 2] : 0); - } - - return -EINVAL; + return res == X86EMUL_OKAY ? val : -ENODEV; } long do_fpu_taskswitch(int set) diff --git a/xen/arch/x86/x86_emulate.c b/xen/arch/x86/x86_emulate.c index 0729edca7b..d260bdca6d 100644 --- a/xen/arch/x86/x86_emulate.c +++ b/xen/arch/x86/x86_emulate.c @@ -87,3 +87,52 @@ int x86emul_write_xcr(unsigned int reg, uint64_t val, return X86EMUL_OKAY; } + +/* Called with NULL ctxt in hypercall context. */ +int x86emul_read_dr(unsigned int reg, unsigned long *val, + struct x86_emulate_ctxt *ctxt) +{ + struct vcpu *curr = current; + + /* HVM support requires a bit more plumbing before it will work. */ + ASSERT(is_pv_vcpu(curr)); + + switch ( reg ) + { + case 0 ... 3: + case 6: + *val = curr->arch.debugreg[reg]; + break; + + case 7: + *val = (curr->arch.debugreg[7] | + curr->arch.debugreg[5]); + break; + + case 4 ... 5: + if ( !(curr->arch.pv_vcpu.ctrlreg[4] & X86_CR4_DE) ) + { + *val = curr->arch.debugreg[reg + 2]; + break; + } + + /* Fallthrough */ + default: + if ( ctxt ) + x86_emul_hw_exception(TRAP_invalid_op, X86_EVENT_NO_EC, ctxt); + + return X86EMUL_EXCEPTION; + } + + return X86EMUL_OKAY; +} + +/* + * Local variables: + * mode: C + * c-file-style: "BSD" + * c-basic-offset: 4 + * tab-width: 4 + * indent-tabs-mode: nil + * End: + */ diff --git a/xen/arch/x86/x86_emulate/x86_emulate.h b/xen/arch/x86/x86_emulate/x86_emulate.h index 13385b0e40..2ae0518ae1 100644 --- a/xen/arch/x86/x86_emulate/x86_emulate.h +++ b/xen/arch/x86/x86_emulate/x86_emulate.h @@ -722,6 +722,9 @@ int x86emul_read_xcr(unsigned int reg, uint64_t *val, int x86emul_write_xcr(unsigned int reg, uint64_t val, struct x86_emulate_ctxt *ctxt); +int x86emul_read_dr(unsigned int reg, unsigned long *val, + struct x86_emulate_ctxt *ctxt); + #endif int -- generated by git-patchbot for /home/xen/git/xen.git#master _______________________________________________ Xen-changelog mailing list Xen-changelog@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/xen-changelog
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