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authorJens Axboe <axboe@kernel.dk>2022-07-24 18:41:03 -0600
committerJens Axboe <axboe@kernel.dk>2022-07-24 18:41:03 -0600
commit4effe18fc0da27ae5d51a702841e87fa13b8a32d (patch)
tree468f353a3713c93b27e7b2c262efd747e66ff199 /arch/x86/kvm/emulate.c
parentMerge branch 'io_uring-zerocopy-send' of git://git.kernel.org/pub/scm/linux/k... (diff)
parentio_uring: ensure REQ_F_ISREG is set async offload (diff)
downloadlinux-4effe18fc0da27ae5d51a702841e87fa13b8a32d.tar.gz
linux-4effe18fc0da27ae5d51a702841e87fa13b8a32d.zip
Merge branch 'for-5.20/io_uring' into for-5.20/io_uring-zerocopy-send
* for-5.20/io_uring: (716 commits) io_uring: ensure REQ_F_ISREG is set async offload net: fix compat pointer in get_compat_msghdr() io_uring: Don't require reinitable percpu_ref io_uring: fix types in io_recvmsg_multishot_overflow io_uring: Use atomic_long_try_cmpxchg in __io_account_mem io_uring: support multishot in recvmsg net: copy from user before calling __get_compat_msghdr net: copy from user before calling __copy_msghdr io_uring: support 0 length iov in buffer select in compat io_uring: fix multishot ending when not polled io_uring: add netmsg cache io_uring: impose max limit on apoll cache io_uring: add abstraction around apoll cache io_uring: move apoll cache to poll.c io_uring: consolidate hash_locked io-wq handling io_uring: clear REQ_F_HASH_LOCKED on hash removal io_uring: don't race double poll setting REQ_F_ASYNC_DATA io_uring: don't miss setting REQ_F_DOUBLE_POLL io_uring: disable multishot recvmsg io_uring: only trace one of complete or overflow ... Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'arch/x86/kvm/emulate.c')
-rw-r--r--arch/x86/kvm/emulate.c35
1 files changed, 18 insertions, 17 deletions
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index 89b11e7dca8a..f8382abe22ff 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -189,9 +189,6 @@
#define X8(x...) X4(x), X4(x)
#define X16(x...) X8(x), X8(x)
-#define NR_FASTOP (ilog2(sizeof(ulong)) + 1)
-#define FASTOP_SIZE (8 * (1 + HAS_KERNEL_IBT))
-
struct opcode {
u64 flags;
u8 intercept;
@@ -306,9 +303,15 @@ static void invalidate_registers(struct x86_emulate_ctxt *ctxt)
* Moreover, they are all exactly FASTOP_SIZE bytes long, so functions for
* different operand sizes can be reached by calculation, rather than a jump
* table (which would be bigger than the code).
+ *
+ * The 16 byte alignment, considering 5 bytes for the RET thunk, 3 for ENDBR
+ * and 1 for the straight line speculation INT3, leaves 7 bytes for the
+ * body of the function. Currently none is larger than 4.
*/
static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
+#define FASTOP_SIZE 16
+
#define __FOP_FUNC(name) \
".align " __stringify(FASTOP_SIZE) " \n\t" \
".type " name ", @function \n\t" \
@@ -325,13 +328,15 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
#define FOP_RET(name) \
__FOP_RET(#name)
-#define FOP_START(op) \
+#define __FOP_START(op, align) \
extern void em_##op(struct fastop *fake); \
asm(".pushsection .text, \"ax\" \n\t" \
".global em_" #op " \n\t" \
- ".align " __stringify(FASTOP_SIZE) " \n\t" \
+ ".align " __stringify(align) " \n\t" \
"em_" #op ":\n\t"
+#define FOP_START(op) __FOP_START(op, FASTOP_SIZE)
+
#define FOP_END \
".popsection")
@@ -435,17 +440,12 @@ static int fastop(struct x86_emulate_ctxt *ctxt, fastop_t fop);
/*
* Depending on .config the SETcc functions look like:
*
- * ENDBR [4 bytes; CONFIG_X86_KERNEL_IBT]
- * SETcc %al [3 bytes]
- * RET [1 byte]
- * INT3 [1 byte; CONFIG_SLS]
- *
- * Which gives possible sizes 4, 5, 8 or 9. When rounded up to the
- * next power-of-two alignment they become 4, 8 or 16 resp.
+ * ENDBR [4 bytes; CONFIG_X86_KERNEL_IBT]
+ * SETcc %al [3 bytes]
+ * RET | JMP __x86_return_thunk [1,5 bytes; CONFIG_RETHUNK]
+ * INT3 [1 byte; CONFIG_SLS]
*/
-#define SETCC_LENGTH (ENDBR_INSN_SIZE + 4 + IS_ENABLED(CONFIG_SLS))
-#define SETCC_ALIGN (4 << IS_ENABLED(CONFIG_SLS) << HAS_KERNEL_IBT)
-static_assert(SETCC_LENGTH <= SETCC_ALIGN);
+#define SETCC_ALIGN 16
#define FOP_SETCC(op) \
".align " __stringify(SETCC_ALIGN) " \n\t" \
@@ -453,9 +453,10 @@ static_assert(SETCC_LENGTH <= SETCC_ALIGN);
#op ": \n\t" \
ASM_ENDBR \
#op " %al \n\t" \
- __FOP_RET(#op)
+ __FOP_RET(#op) \
+ ".skip " __stringify(SETCC_ALIGN) " - (.-" #op "), 0xcc \n\t"
-FOP_START(setcc)
+__FOP_START(setcc, SETCC_ALIGN)
FOP_SETCC(seto)
FOP_SETCC(setno)
FOP_SETCC(setc)