diff options
Diffstat (limited to 'lib/libc/i386/gen/getcontext.S')
| -rw-r--r-- | lib/libc/i386/gen/getcontext.S | 51 |
1 files changed, 22 insertions, 29 deletions
diff --git a/lib/libc/i386/gen/getcontext.S b/lib/libc/i386/gen/getcontext.S index 9e799d5..3fcdff3 100644 --- a/lib/libc/i386/gen/getcontext.S +++ b/lib/libc/i386/gen/getcontext.S @@ -30,14 +30,13 @@ __FBSDID("$FreeBSD$"); /* * Where do we define these? */ -#define UC_MC_VALID 0x0001 /* __UC_MC_VALID <machine/ucontext.h> */ -#define UC_FP_VALID 0x0002 /* __UC_FP_VALID <machine/ucontext.h> */ -#define MC_FP_VALID UC_MC_VALID | UC_FP_VALID +#define MC_SIZE 640 /* sizeof mcontext_t */ #define UC_MC_OFFSET 16 /* offset to mcontext from ucontext */ -#define UC_FLAGS_OFFSET 208 /* offset to flags from ucontext */ -#define MC_FLAGS_OFFSET 192 /* offset to flags from mcontext */ -#define MC_FP_REGS_OFFSET 80 /* offset to FP regs from mcontext */ -#define MC_FP_CW_OFFSET 80 /* offset to FP control word */ +#define UC_MC_LEN_OFFSET 96 /* offset to mc_len from mcontext */ +#define MC_LEN_OFFSET 80 /* offset to mc_len from mcontext */ +#define MC_FP_REGS_OFFSET 96 /* offset to FP regs from mcontext */ +#define MC_FP_CW_OFFSET 96 /* offset to FP control word */ +#define MC_OWNEDFP_OFFSET 88 /* offset to mc_ownedfp from mcontext */ /* * int setcontext(ucontext_t *ucp); @@ -54,8 +53,8 @@ ENTRY(__setcontext) jne 1f movl $-1, %eax jmp 5f -1: testl $UC_MC_VALID, UC_FLAGS_OFFSET(%eax) /* is context valid? */ - jnz 2f +1: cmpl $MC_SIZE, UC_MC_LEN_OFFSET(%eax) /* is context valid? */ + je 2f movl $-1, %eax /* bzzzt, invalid context */ jmp 5f 2: PIC_PROLOGUE @@ -80,18 +79,19 @@ ENTRY(__setcontext) subl $4, %esp /* leave space for the return address */ movl 60(%edx), %eax /* put return address at top of stack */ movl %eax, (%esp) - testl $UC_FP_VALID, MC_FLAGS_OFFSET(%edx) /* are FP regs valid? */ + cmpl $0, MC_OWNEDFP_OFFSET(%edx) /* are FP regs valid? */ jz 3f frstor MC_FP_REGS_OFFSET(%edx) /* restore FP regs */ jmp 4f 3: fninit fldcw MC_FP_CW_OFFSET(%edx) -4: movl 68(%edx), %eax /* restore flags register */ - sahf - movl 48(%edx), %eax /* restore ax, bx, cx, and dx last */ +4: movl 48(%edx), %eax /* restore ax, bx, cx */ movl 36(%edx), %ebx movl 44(%edx), %ecx - movl 40(%edx), %edx + pushl 68(%edx) /* flags on stack */ + pushl 40(%edx) /* %edx on stack */ + popl %edx /* %edx off stack */ + popf /* flags off stack */ 5: ret /* @@ -109,8 +109,8 @@ ENTRY(__getcontext) jne 1f movl $-1, %eax jmp 2f - movl 4(%esp), %eax /* get address of context and sigset */ -1: PIC_PROLOGUE +1: movl 4(%esp), %eax /* get address of context and sigset */ + PIC_PROLOGUE pushl %eax /* oset = &ucp->uc_sigmask */ pushl $0 /* set = NULL */ pushl $3 /* how = SIG_SETMASK */ @@ -136,30 +136,23 @@ ENTRY(__getcontext) movl %ecx, 44(%edx) movl (%esp), %eax /* get return address */ movl %eax, 60(%edx) /* save return address */ + movl %ss, 76(%edx) /* - * XXX - Do we really need to save floating point registers? + * Don't save floating point registers here. * * This is an explicit call to get the current context, so - * shouldn't the caller be done with the floating point registers? + * the caller is done with the floating point registers. * Contexts formed by involuntary switches, such as signal delivery, - * should have floating point registers saved by the kernel. - * - * As of this writing, the kernel doesn't yet save the FPU state - * on signal delivery, so a setcontext on the interrupted context - * may yield incorrect results regardless. + * have floating point registers saved by the kernel. */ -#if 1 fnstcw MC_FP_CW_OFFSET(%edx) - movl $UC_MC_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext valid, no FP */ -#else - fnsave MC_FP_REGS_OFFSET(%edx) /* save FP regs */ - movl $MC_FP_VALID, MC_FLAGS_OFFSET(%edx) /* mcontext and FP valid */ -#endif + movl $0, MC_OWNEDFP_OFFSET(%edx) /* no FP */ lahf /* get eflags */ movl %eax, 68(%edx) /* store eflags */ movl %esp, %eax /* setcontext pushes the return */ addl $4, %eax /* address onto the top of the */ movl %eax, 72(%edx) /* stack; account for this */ + movl $MC_SIZE, MC_LEN_OFFSET(%edx) /* context is now valid */ movl 40(%edx), %edx /* restore edx -- is this needed? */ xorl %eax, %eax /* return 0 */ 2: ret |
