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authorH. Peter Anvin <hpa@linux.intel.com>2010-09-14 12:42:41 -0700
committerH. Peter Anvin <hpa@linux.intel.com>2010-09-14 16:08:46 -0700
commit36d001c70d8a0144ac1d038f6876c484849a74de (patch)
tree98e061ce49af5ce48d6d67ffe5d3258563f4445d
parentc41d68a513c71e35a14f66d71782d27a79a81ea6 (diff)
x86-64, compat: Test %rax for the syscall number, not %eax
On 64 bits, we always, by necessity, jump through the system call table via %rax. For 32-bit system calls, in theory the system call number is stored in %eax, and the code was testing %eax for a valid system call number. At one point we loaded the stored value back from the stack to enforce zero-extension, but that was removed in checkin d4d67150165df8bf1cc05e532f6efca96f907cab. An actual 32-bit process will not be able to introduce a non-zero-extended number, but it can happen via ptrace. Instead of re-introducing the zero-extension, test what we are actually going to use, i.e. %rax. This only adds a handful of REX prefixes to the code. Reported-by: Ben Hawkes <hawkes@sota.gen.nz> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@kernel.org> Cc: Roland McGrath <roland@redhat.com> Cc: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--arch/x86/ia32/ia32entry.S14
1 files changed, 7 insertions, 7 deletions
diff --git a/arch/x86/ia32/ia32entry.S b/arch/x86/ia32/ia32entry.S
index b86feab..84e3a4e 100644
--- a/arch/x86/ia32/ia32entry.S
+++ b/arch/x86/ia32/ia32entry.S
@@ -153,7 +153,7 @@ ENTRY(ia32_sysenter_target)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
CFI_REMEMBER_STATE
jnz sysenter_tracesys
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja ia32_badsys
sysenter_do_call:
IA32_ARG_FIXUP
@@ -195,7 +195,7 @@ sysexit_from_sys_call:
movl $AUDIT_ARCH_I386,%edi /* 1st arg: audit arch */
call audit_syscall_entry
movl RAX-ARGOFFSET(%rsp),%eax /* reload syscall number */
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja ia32_badsys
movl %ebx,%edi /* reload 1st syscall arg */
movl RCX-ARGOFFSET(%rsp),%esi /* reload 2nd syscall arg */
@@ -248,7 +248,7 @@ sysenter_tracesys:
call syscall_trace_enter
LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja int_ret_from_sys_call /* sysenter_tracesys has set RAX(%rsp) */
jmp sysenter_do_call
CFI_ENDPROC
@@ -314,7 +314,7 @@ ENTRY(ia32_cstar_target)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
CFI_REMEMBER_STATE
jnz cstar_tracesys
- cmpl $IA32_NR_syscalls-1,%eax
+ cmpq $IA32_NR_syscalls-1,%rax
ja ia32_badsys
cstar_do_call:
IA32_ARG_FIXUP 1
@@ -367,7 +367,7 @@ cstar_tracesys:
LOAD_ARGS32 ARGOFFSET, 1 /* reload args from stack in case ptrace changed it */
RESTORE_REST
xchgl %ebp,%r9d
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja int_ret_from_sys_call /* cstar_tracesys has set RAX(%rsp) */
jmp cstar_do_call
END(ia32_cstar_target)
@@ -425,7 +425,7 @@ ENTRY(ia32_syscall)
orl $TS_COMPAT,TI_status(%r10)
testl $_TIF_WORK_SYSCALL_ENTRY,TI_flags(%r10)
jnz ia32_tracesys
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja ia32_badsys
ia32_do_call:
IA32_ARG_FIXUP
@@ -444,7 +444,7 @@ ia32_tracesys:
call syscall_trace_enter
LOAD_ARGS32 ARGOFFSET /* reload args from stack in case ptrace changed it */
RESTORE_REST
- cmpl $(IA32_NR_syscalls-1),%eax
+ cmpq $(IA32_NR_syscalls-1),%rax
ja int_ret_from_sys_call /* ia32_tracesys has set RAX(%rsp) */
jmp ia32_do_call
END(ia32_syscall)