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author | Denys Vlasenko <vda.linux@googlemail.com> | 2013-02-17 13:17:49 +0100 |
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committer | Denys Vlasenko <vda.linux@googlemail.com> | 2013-02-17 13:17:49 +0100 |
commit | 09a87ae9712acb3725fb76d3f71215e168215611 (patch) | |
tree | 3bdbe689d0cf133477ec5b4d06369c4bfabb1615 | |
parent | 782d90f9187e290f4523efe04a6e0eacdeb68613 (diff) | |
download | strace-09a87ae9712acb3725fb76d3f71215e168215611.tar.gz strace-09a87ae9712acb3725fb76d3f71215e168215611.tar.bz2 strace-09a87ae9712acb3725fb76d3f71215e168215611.tar.xz |
Remove wrong x32-specific lseek
Testing confirmed what I suspected: x32 lseek uses kernel-sized
(i.e. wide) long for offset parameter.
* file.c: Delete sys_lseek32.
* linux/syscall.h: Likewise.
* linux/x32/syscallent1.h: Likewise.
* test/x32_lseek.c: New file.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
-rw-r--r-- | file.c | 26 | ||||
-rw-r--r-- | linux/syscall.h | 4 | ||||
-rw-r--r-- | linux/x32/syscallent1.h | 1 | ||||
-rw-r--r-- | test/x32_lseek.c | 38 |
4 files changed, 41 insertions, 28 deletions
@@ -528,6 +528,7 @@ static const struct xlat whence_codes[] = { * In kernel, off_t is always the same as (kernel's) long * (see include/uapi/asm-generic/posix_types.h), * which means that on x32 we need to use tcp->ext_arg[N] to get offset argument. + * Use test/x32_lseek.c to test lseek decoding. */ #if defined(LINUX_MIPSN32) || defined(X32) int @@ -548,27 +549,6 @@ sys_lseek(struct tcb *tcp) } return RVAL_LUDECIMAL; } - -# if defined(X32) -int -sys_lseek32(struct tcb *tcp) -{ - long offset; - int whence; - - if (entering(tcp)) { - printfd(tcp, tcp->u_arg[0]); - offset = tcp->u_arg[1]; - whence = tcp->u_arg[2]; - if (whence == SEEK_SET) - tprintf(", %lu, ", offset); - else - tprintf(", %ld, ", offset); - printxval(whence_codes, whence, "SEEK_???"); - } - return RVAL_UDECIMAL; -} -# endif #else int sys_lseek(struct tcb *tcp) @@ -598,9 +578,9 @@ sys_lseek(struct tcb *tcp) * * hi,lo are "unsigned longs" and combined exactly this way in kernel: * ((loff_t) hi << 32) | lo - * Note that for architectures with kernel's long wider than userspace longs + * Note that for architectures with kernel's long wider than userspace long * (such as x32), combining code will use *kernel's*, i.e. *wide* longs - * for hi and lo. You may need to use tcp->ext_arg[N]! + * for hi and lo. We may need to use tcp->ext_arg[N]! */ int sys_llseek(struct tcb *tcp) diff --git a/linux/syscall.h b/linux/syscall.h index c0f955b..0107564 100644 --- a/linux/syscall.h +++ b/linux/syscall.h @@ -373,7 +373,3 @@ int sys_shmsys(); #define SYS_shmsys_subcall 207 #define SYS_shmsys_nsubcalls 4 #endif - -#ifdef X32 -int sys_lseek32(); -#endif diff --git a/linux/x32/syscallent1.h b/linux/x32/syscallent1.h index 20c6529..e58372e 100644 --- a/linux/x32/syscallent1.h +++ b/linux/x32/syscallent1.h @@ -4,7 +4,6 @@ #define sys_oldstat printargs #define sys_oldfstat printargs #define sys_oldlstat printargs -#define sys_lseek sys_lseek32 #define sys_lstat64 sys_stat64 #define sys_truncate64 sys_truncate #define sys_ftruncate64 sys_ftruncate diff --git a/test/x32_lseek.c b/test/x32_lseek.c new file mode 100644 index 0000000..6faa2fa --- /dev/null +++ b/test/x32_lseek.c @@ -0,0 +1,38 @@ +// Test program which explores whether lseek syscall (not llseek!) +// on x32 uses 64-bit offset argument. +// IOW: does _kernel_ truncate it on entry? +// The answer appears to be "no, full 64-bit offset is used". +// strace must show it correctly too - tricky if strace itself is x32 one! +// +// Build: x86_64-gcc -static -Wall -ox32_lseek x32_lseek.c +// Run: $ strace ./x32_lseek 2>&1 | grep lseek | grep 1250999896321 +// lseek(0, 1250999896321, SEEK_SET) = 1250999896321 +#define _GNU_SOURCE +#include <sys/types.h> +#include <stdlib.h> +#include <unistd.h> +#include <errno.h> +#include <sys/stat.h> +#include <fcntl.h> +#include <stdio.h> +#include <sys/syscall.h> +// Ensure we are compiling to 64 bits +struct bug { int t[sizeof(long) > 4 ? 1 : -1]; }; +int main(int argc, char **argv) +{ + long ofs = 0x12345678901; + errno = 0; + close(0); + if (open("/etc/passwd", O_RDONLY)) + return 1; + long r = syscall( + (long) (__NR_lseek | 0x40000000), // make x32 call + (long) (0), + (long) (ofs), + (long) (SEEK_SET) + ); + printf("pos:%ld(0x%lx) errno:%m\n", r, r); + if (!errno) + printf((r == ofs) ? "64-bit offset used\n" : "Kernel truncated offset\n"); + return 0; +} |