diff options
| -rw-r--r-- | coregrind/vg_to_ucode.c | 17 | ||||
| -rw-r--r-- | vg_to_ucode.c | 17 |
2 files changed, 32 insertions, 2 deletions
diff --git a/coregrind/vg_to_ucode.c b/coregrind/vg_to_ucode.c index 5cef0b84..c03f5817 100644 --- a/coregrind/vg_to_ucode.c +++ b/coregrind/vg_to_ucode.c @@ -2644,8 +2644,23 @@ void codegen_xchg_eAX_Reg ( UCodeBlock* cb, Int sz, Int reg ) static void codegen_SAHF ( UCodeBlock* cb ) { - Int t = newTemp(cb); + Int t = newTemp(cb); + Int t2 = newTemp(cb); uInstr2(cb, GET, 4, ArchReg, R_EAX, TempReg, t); + + /* Mask out parts of t not corresponding to %AH. This stops the + instrumenter complaining if they are undefined. Otherwise, the + instrumenter would check all 32 bits of t at the PUSH, which + could be the cause of incorrect warnings. Discovered by Daniel + Veillard <veillard@redhat.com>. + */ + uInstr2(cb, MOV, 4, Literal, 0, TempReg, t2); + uLiteral(cb, 0x0000FF00); + uInstr2(cb, AND, 4, TempReg, t2, TempReg, t); + /* We deliberately don't set the condition codes here, since this + AND is purely internal to Valgrind and nothing to do with the + client's state. */ + uInstr0(cb, CALLM_S, 0); uInstr1(cb, PUSH, 4, TempReg, t); uInstr1(cb, CALLM, 0, Lit16, VGOFF_(helper_SAHF)); diff --git a/vg_to_ucode.c b/vg_to_ucode.c index 5cef0b84..c03f5817 100644 --- a/vg_to_ucode.c +++ b/vg_to_ucode.c @@ -2644,8 +2644,23 @@ void codegen_xchg_eAX_Reg ( UCodeBlock* cb, Int sz, Int reg ) static void codegen_SAHF ( UCodeBlock* cb ) { - Int t = newTemp(cb); + Int t = newTemp(cb); + Int t2 = newTemp(cb); uInstr2(cb, GET, 4, ArchReg, R_EAX, TempReg, t); + + /* Mask out parts of t not corresponding to %AH. This stops the + instrumenter complaining if they are undefined. Otherwise, the + instrumenter would check all 32 bits of t at the PUSH, which + could be the cause of incorrect warnings. Discovered by Daniel + Veillard <veillard@redhat.com>. + */ + uInstr2(cb, MOV, 4, Literal, 0, TempReg, t2); + uLiteral(cb, 0x0000FF00); + uInstr2(cb, AND, 4, TempReg, t2, TempReg, t); + /* We deliberately don't set the condition codes here, since this + AND is purely internal to Valgrind and nothing to do with the + client's state. */ + uInstr0(cb, CALLM_S, 0); uInstr1(cb, PUSH, 4, TempReg, t); uInstr1(cb, CALLM, 0, Lit16, VGOFF_(helper_SAHF)); |