From 87b70b32fadb057d9eabb81e4f1d57742217b590 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 9 Jun 2009 11:34:00 -0700 Subject: memdisk: don't use the stack before bootstrap Under some certain circumstances, it might not be safe to use the stack as it was set up, so use a jump instead of a call to invoke the bootstrap. Signed-off-by: H. Peter Anvin --- memdisk/memdisk16.asm | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/memdisk/memdisk16.asm b/memdisk/memdisk16.asm index 0c5b9973..6bafae7f 100644 --- a/memdisk/memdisk16.asm +++ b/memdisk/memdisk16.asm @@ -159,8 +159,7 @@ copy_cmdline: mov gs,si lss sp,[cs:b_sssp] movzx esp,sp - call far [cs:b_csip] - int 18h ; A far return -> INT 18h + jmp far [cs:b_csip] ; ; We enter protected mode, set up a flat 32-bit environment, run rep movsd -- cgit v1.2.1 From 21e8f68b76dda9fa4dd8a70fcfe1d574cad37cc5 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Tue, 9 Jun 2009 22:50:55 -0700 Subject: com32.h: cleanups, make OFFS_VALID() take the pointer size into account Clean up some of the constructs in com32.h, and make OFFS_VALID() take the pointer type into account for the range check -- the whole object needs to fit within the segment. Signed-off-by: H. Peter Anvin --- com32/include/com32.h | 29 ++++++++++++++++++++--------- 1 file changed, 20 insertions(+), 9 deletions(-) diff --git a/com32/include/com32.h b/com32/include/com32.h index c003f7ca..aa7fb4b6 100644 --- a/com32/include/com32.h +++ b/com32/include/com32.h @@ -36,6 +36,8 @@ #define _COM32_H #include +#include +#include #include /* For __cdecl */ /* @@ -132,17 +134,20 @@ static inline uint16_t OFFS(const volatile void *__p) return (uint16_t) (uintptr_t) __p & 0x000F; } -static inline uint16_t OFFS_WRT(const volatile void *__p, uint16_t seg) +static inline uint16_t OFFS_WRT(const volatile void *__p, uint16_t __seg) { - return (uint16_t) ((uintptr_t) __p - ((uintptr_t) seg << 4)); + return (uint16_t) ((uintptr_t) __p - ((uintptr_t) __seg << 4)); } -static inline int OFFS_VALID(const volatile void *__p, uint16_t seg) +#define OFFS_VALID(p,s) _OFFS_VALID((p), sizeof *(p), (s)) + +static inline bool _OFFS_VALID(const volatile void *__p, size_t __s, + uint16_t __seg) { - uintptr_t __segstart = (uintptr_t) seg << 4; - uintptr_t __ptr = (uintptr_t) __p; + uintptr_t __segstart = (uintptr_t)__seg << 4; + uintptr_t __offs = (uintptr_t)__p - __segstart; - return (__ptr >= __segstart) && (__ptr <= __segstart + 0xffff); + return __offs <= 0x10000-__s; } static inline void *MK_PTR(uint16_t __seg, uint16_t __offs) @@ -153,21 +158,27 @@ static inline void *MK_PTR(uint16_t __seg, uint16_t __offs) /* Some tools to handle 16:16 far pointers in memory */ struct __far_ptr { - uint32_t __ptr; + union { + uint32_t ptr; + struct { + uint16_t offs, seg; + }; + }; } __attribute__ ((packed)); typedef struct __far_ptr far_ptr_t; static inline void *GET_PTR(far_ptr_t __fptr) { - return MK_PTR(__fptr.__ptr >> 16, __fptr.__ptr); + return MK_PTR(__fptr.seg, __fptr.offs); } static inline far_ptr_t FAR_PTR(void *__ptr) { far_ptr_t __fptr; - __fptr.__ptr = (SEG(__ptr) << 16) + OFFS(__ptr); + __fptr.offs = OFFS(__ptr); + __fptr.seg = SEG(__ptr); return __fptr; } -- cgit v1.2.1