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[Qemu-devel] [PATCH 05/11] tcg/i386: Make direct jump patching thread-sa
From: |
Sergey Fedorov |
Subject: |
[Qemu-devel] [PATCH 05/11] tcg/i386: Make direct jump patching thread-safe |
Date: |
Thu, 7 Apr 2016 18:53:47 +0300 |
From: Sergey Fedorov <address@hidden>
Ensure direct jump patching in i386 is atomic by:
* naturally aligning a location of direct jump address;
* using atomic_read()/atomic_set() for code patching.
Signed-off-by: Sergey Fedorov <address@hidden>
Signed-off-by: Sergey Fedorov <address@hidden>
---
include/exec/exec-all.h | 2 +-
tcg/i386/tcg-target.inc.c | 17 +++++++++++++++++
2 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/include/exec/exec-all.h b/include/exec/exec-all.h
index 59709c9dd5c9..82399175fe80 100644
--- a/include/exec/exec-all.h
+++ b/include/exec/exec-all.h
@@ -312,7 +312,7 @@ void ppc_tb_set_jmp_target(uintptr_t jmp_addr, uintptr_t
addr);
static inline void tb_set_jmp_target1(uintptr_t jmp_addr, uintptr_t addr)
{
/* patch the branch destination */
- stl_le_p((void*)jmp_addr, addr - (jmp_addr + 4));
+ atomic_set((int32_t *)jmp_addr, addr - (jmp_addr + 4));
/* no need to flush icache explicitly */
}
#elif defined(__s390x__)
diff --git a/tcg/i386/tcg-target.inc.c b/tcg/i386/tcg-target.inc.c
index 9187d34caf6d..3ffb7b3124d8 100644
--- a/tcg/i386/tcg-target.inc.c
+++ b/tcg/i386/tcg-target.inc.c
@@ -1123,6 +1123,19 @@ static void tcg_out_jmp(TCGContext *s, tcg_insn_unit
*dest)
tcg_out_branch(s, 0, dest);
}
+static void tcg_out_nopn(TCGContext *s, int n)
+{
+ static const uint8_t nop1[] = { 0x90 };
+ static const uint8_t nop2[] = { 0x66, 0x90 };
+ static const uint8_t nop3[] = { 0x8d, 0x76, 0x00 };
+ static const uint8_t *const nopn[] = { nop1, nop2, nop3 };
+ int i;
+ assert(n <= ARRAY_SIZE(nopn));
+ for (i = 0; i < n; ++i) {
+ tcg_out8(s, nopn[n - 1][i]);
+ }
+}
+
#if defined(CONFIG_SOFTMMU)
/* helper signature: helper_ret_ld_mmu(CPUState *env, target_ulong addr,
* int mmu_idx, uintptr_t ra)
@@ -1777,6 +1790,10 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode
opc,
case INDEX_op_goto_tb:
if (s->tb_jmp_offset) {
/* direct jump method */
+ /* align jump displacement for atomic pathing */
+ if (((uintptr_t)s->code_ptr & 3) != 3) {
+ tcg_out_nopn(s, 3 - ((uintptr_t)s->code_ptr & 3));
+ }
tcg_out8(s, OPC_JMP_long); /* jmp im */
s->tb_jmp_offset[args[0]] = tcg_current_code_size(s);
tcg_out32(s, 0);
--
2.8.1
- Re: [Qemu-devel] [PATCH 03/11] tci: Make direct jump patching thread-safe, (continued)
[Qemu-devel] [PATCH 06/11] tcg/s390: Make direct jump patching thread-safe, Sergey Fedorov, 2016/04/07
[Qemu-devel] [PATCH 01/11] tci: Fix build regression, Sergey Fedorov, 2016/04/07
[Qemu-devel] [PATCH 05/11] tcg/i386: Make direct jump patching thread-safe,
Sergey Fedorov <=
[Qemu-devel] [PATCH 02/11] pc-bios/s390-ccw: Use correct strip when cross-compiling, Sergey Fedorov, 2016/04/07