From: Peter Zijlstra <peterz@infradead.org>
To: x86@kernel.org
Cc: linux-kernel@vger.kernel.org, peterz@infradead.org,
jpoimboe@redhat.com, mark.rutland@arm.com, dvyukov@google.com,
seanjc@google.com, pbonzini@redhat.com, mbenes@suse.cz
Subject: [RFC][PATCH 18/22] x86,kvm: Remove .fixup usage
Date: Thu, 04 Nov 2021 17:47:47 +0100 [thread overview]
Message-ID: <20211104165525.588957687@infradead.org> (raw)
In-Reply-To: 20211104164729.226550532@infradead.org
KVM instruction emulation has a gnarly hack where the .fixup does a
return, luckily exceptions can easily emulate a return so create a new
extable type to fully do the FASTOP magic.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
arch/x86/include/asm/extable_fixup_types.h | 1 +
arch/x86/kvm/emulate.c | 14 +++-----------
arch/x86/mm/extable.c | 11 +++++++++++
3 files changed, 15 insertions(+), 11 deletions(-)
--- a/arch/x86/include/asm/extable_fixup_types.h
+++ b/arch/x86/include/asm/extable_fixup_types.h
@@ -40,5 +40,6 @@
#define EX_TYPE_ONE_REG (EX_TYPE_IMM_REG | EX_TYPE_IMM(1))
#define EX_TYPE_FAULT_SGX 18
+#define EX_TYPE_KVM_FASTOP 19
#endif
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -344,7 +344,7 @@ static int fastop(struct x86_emulate_ctx
__FOP_RET(#op "_" #dst)
#define FOP1EEX(op, dst) \
- FOP1E(op, dst) _ASM_EXTABLE(10b, kvm_fastop_exception)
+ FOP1E(op, dst) _ASM_EXTABLE_TYPE(10b, 10b, EX_TYPE_KVM_FASTOP)
#define FASTOP1(op) \
FOP_START(op) \
@@ -434,10 +434,6 @@ static int fastop(struct x86_emulate_ctx
#op " %al \n\t" \
__FOP_RET(#op)
-asm(".pushsection .fixup, \"ax\"\n"
- "kvm_fastop_exception: xor %esi, %esi; ret\n"
- ".popsection");
-
FOP_START(setcc)
FOP_SETCC(seto)
FOP_SETCC(setno)
@@ -473,12 +469,8 @@ FOP_END;
\
asm volatile("1:" insn "\n" \
"2:\n" \
- ".pushsection .fixup, \"ax\"\n" \
- "3: movl $1, %[_fault]\n" \
- " jmp 2b\n" \
- ".popsection\n" \
- _ASM_EXTABLE(1b, 3b) \
- : [_fault] "+qm"(_fault) inoutclob ); \
+ _ASM_EXTABLE_TYPE_REG(1b, 2b, EX_TYPE_ONE_REG, %[_fault]) \
+ : [_fault] "+r"(_fault) inoutclob ); \
\
_fault ? X86EMUL_UNHANDLEABLE : X86EMUL_CONTINUE; \
})
--- a/arch/x86/mm/extable.c
+++ b/arch/x86/mm/extable.c
@@ -10,6 +10,7 @@
#include <asm/traps.h>
#include <asm/kdebug.h>
#include <asm/sgx.h>
+#include <asm/text-patching.h>
static inline unsigned long *pt_regs_nr(struct pt_regs *regs, int nr)
{
@@ -154,6 +155,14 @@ static bool ex_handler_sgx(const struct
return ex_handler_default(fixup, regs);
}
+static bool ex_handler_kvm_fastop(const struct exception_table_entry *fixup,
+ struct pt_regs *regs)
+{
+ regs->si = 0;
+ int3_emulate_ret(regs);
+ return true;
+}
+
#define EX_TYPE_MASK 0x000000FF
#define EX_REG_MASK 0x00000F00
#define EX_FLAG_MASK 0x0000F000
@@ -231,6 +240,8 @@ int fixup_exception(struct pt_regs *regs
return ex_handler_imm_reg(e, regs, reg, imm);
case EX_TYPE_FAULT_SGX:
return ex_handler_sgx(e, regs, trapnr);
+ case EX_TYPE_KVM_FASTOP:
+ return ex_handler_kvm_fastop(e, regs);
}
BUG();
}
next prev parent reply other threads:[~2021-11-04 16:56 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-04 16:47 [RFC][PATCH 00/22] x86: Remove anonymous out-of-line fixups Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 01/22] bitfield.h: Fix "type of reg too small for mask" test Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 02/22] x86,mmx_32: Remove .fixup usage Peter Zijlstra
2021-11-04 18:00 ` Borislav Petkov
2021-11-05 11:20 ` David Laight
2021-11-04 20:22 ` Josh Poimboeuf
2021-11-05 8:05 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 03/22] x86,copy_user_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 04/22] x86,copy_mc_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 05/22] x86,entry_64: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 06/22] x86,entry_32: " Peter Zijlstra
2021-11-04 20:39 ` Josh Poimboeuf
2021-11-05 7:43 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 07/22] x86,extable: Extend extable functionality Peter Zijlstra
2021-11-04 21:49 ` Josh Poimboeuf
2021-11-05 7:54 ` Peter Zijlstra
2021-11-05 10:16 ` Mark Rutland
2021-11-05 17:32 ` Sean Christopherson
2021-11-05 18:45 ` Peter Zijlstra
2021-11-05 19:17 ` Sean Christopherson
2021-11-05 19:32 ` Peter Zijlstra
2021-11-05 19:47 ` Sean Christopherson
2021-11-05 20:15 ` Peter Zijlstra
2021-11-05 20:26 ` Peter Zijlstra
2021-11-05 22:30 ` Sean Christopherson
2021-11-04 16:47 ` [RFC][PATCH 08/22] x86,msr: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 09/22] x86,futex: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 10/22] x86,uaccess: " Peter Zijlstra
2021-11-04 22:28 ` Josh Poimboeuf
2021-11-04 16:47 ` [RFC][PATCH 11/22] x86,xen: " Peter Zijlstra
2021-11-04 22:31 ` Josh Poimboeuf
2021-11-05 7:56 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 12/22] x86,fpu: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 13/22] x86,segment: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 14/22] x86,ftrace: " Peter Zijlstra
2021-11-04 22:35 ` Josh Poimboeuf
2021-11-05 7:57 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 15/22] x86,vmx: " Peter Zijlstra
2021-11-04 18:50 ` Paolo Bonzini
2021-11-05 18:17 ` Sean Christopherson
2021-11-05 18:52 ` Peter Zijlstra
2021-11-05 20:58 ` Peter Zijlstra
2021-11-05 22:29 ` Sean Christopherson
2021-11-06 7:05 ` Paolo Bonzini
2021-11-06 8:36 ` Peter Zijlstra
2021-11-07 19:13 ` Paolo Bonzini
2021-11-06 8:28 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 16/22] x86,checksum_32: " Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 17/22] x86,sgx: " Peter Zijlstra
2021-11-04 16:47 ` Peter Zijlstra [this message]
2021-11-04 18:50 ` [RFC][PATCH 18/22] x86,kvm: " Paolo Bonzini
2021-11-05 7:58 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 19/22] x86,usercopy_32: Simplify Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 20/22] x86,usercopy: Remove .fixup usage Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 21/22] x86,word-at-a-time: " Peter Zijlstra
2021-11-04 23:33 ` Josh Poimboeuf
2021-11-05 8:04 ` Peter Zijlstra
2021-11-04 16:47 ` [RFC][PATCH 22/22] x86: Remove .fixup section Peter Zijlstra
2021-11-04 23:00 ` Josh Poimboeuf
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