Index: syscall_entrypoint.cc |
=================================================================== |
--- syscall_entrypoint.cc (revision 167) |
+++ syscall_entrypoint.cc (working copy) |
@@ -176,7 +176,7 @@ |
"mov %ebx, %eax\n" // NR_exit |
"jmp 0b\n" |
"1:cmp $173, %eax\n" // NR_rt_sigreturn |
- "jnz 3f\n" |
+ "jnz 4f\n" |
// Convert rt_sigframe into sigframe, allowing us to call sigreturn(). |
// This is possible since the first part of signal stack frames have |
@@ -202,19 +202,21 @@ |
"rep movsl\n" |
"mov 0x2C8(%esp), %ebx\n" // copy first half of signal mask |
"mov %ebx, 0x54(%esp)\n" |
- "lea 2f, %esi\n" |
+ "call 2f\n" |
+ "2:pop %esi\n" |
+ "add $(3f-2b), %esi\n" |
"push %esi\n" // push restorer function |
"lea 0x2D4(%esp), %edi\n" // patch up retcode magic numbers |
"movb $2, %cl\n" |
"rep movsl\n" |
"ret\n" // return to restorer function |
- "2:pop %eax\n" // remove dummy argument (signo) |
+ "3:pop %eax\n" // remove dummy argument (signo) |
"mov $119, %eax\n" // NR_sigaction |
"int $0x80\n" |
// Preserve all registers |
- "3:push %ebp\n" |
+ "4:push %ebp\n" |
"push $0xDEADBEEF\n" // marker used by breakpad |
"push %ebx\n" |
"push %ecx\n" |
@@ -242,8 +244,12 @@ |
"push %eax\n" |
// Check range of system call |
- "cmp playground$maxSyscall, %eax\n" |
- "ja 9f\n" |
+ "call 5f\n" |
+ "5:pop %edx\n" |
+ "add $(_GLOBAL_OFFSET_TABLE_+(.-5b)), %edx\n" |
+ "mov playground$maxSyscall@GOT(%edx), %edx\n" |
+ "cmp 0(%edx), %eax\n" |
+ "ja 14f\n" |
// We often have long sequences of calls to gettimeofday(). This is |
// needlessly expensive. Coalesce them into a single call. |
@@ -257,9 +263,9 @@ |
// or maybe, if we have recently seen requests to compute |
// the time. There might be a repeated pattern of those. |
"cmp $78, %eax\n" // __NR_gettimeofday |
- "jnz 6f\n" |
+ "jnz 10f\n" |
"cmp %eax, %fs:0x102C-0x58\n" // last system call |
- "jnz 4f\n" |
+ "jnz 7f\n" |
// This system call and the last system call prior to this one both are |
// calls to gettimeofday(). Try to avoid making the new call and just |
@@ -267,44 +273,50 @@ |
// Just in case the caller is spinning on the result from gettimeofday(), |
// every so often, call the actual system call. |
"decl %fs:0x1030-0x58\n" // countdown calls to gettimofday() |
- "jz 4f\n" |
+ "jz 7f\n" |
// Atomically read the 64bit word representing last-known timestamp and |
// return it to the caller. On x86-32 this is a little more complicated and |
// requires the use of the cmpxchg8b instruction. |
"mov %ebx, %eax\n" |
"mov %ecx, %edx\n" |
- "lock; cmpxchg8b 100f\n" |
+ "call 6f\n" |
+ "6:pop %ebp\n" |
+ "add $(100f-6b), %ebp\n" |
+ "lock; cmpxchg8b 0(%ebp)\n" |
"mov %eax, 0(%ebx)\n" |
"mov %edx, 4(%ebx)\n" |
"xor %eax, %eax\n" |
"add $28, %esp\n" |
- "jmp 8f\n" |
+ "jmp 13f\n" |
// This is a call to gettimeofday(), but we don't have a valid cached |
// result, yet. |
- "4:mov %eax, %fs:0x102C-0x58\n" // remember syscall number |
+ "7:mov %eax, %fs:0x102C-0x58\n" // remember syscall number |
"movl $500, %fs:0x1030-0x58\n" // make system call, each 500 invocations |
- "call playground$defaultSystemCallHandler\n" |
+ "call playground$defaultSystemCallHandler@PLT\n" |
// Returned from gettimeofday(). Remember return value, in case the |
// application calls us again right away. |
// Again, this has to happen atomically and requires cmpxchg8b. |
"mov 4(%ebx), %ecx\n" |
"mov 0(%ebx), %ebx\n" |
- "mov 100f, %eax\n" |
- "mov 101f, %edx\n" |
- "5:lock; cmpxchg8b 100f\n" |
- "jnz 5b\n" |
+ "call 8f\n" |
+ "8:pop %ebp\n" |
+ "add $(100f-8b), %ebp\n" |
+ "mov 0(%ebp), %eax\n" |
+ "mov 4(%ebp), %edx\n" |
+ "9:lock; cmpxchg8b 0(%ebp)\n" |
+ "jnz 9b\n" |
"xor %eax, %eax\n" |
- "jmp 10f\n" |
+ "jmp 15f\n" |
// Remember the number of the last system call made. We deliberately do |
// not remember calls to gettid(), as we have often seen long sequences |
// of calls to just gettimeofday() and gettid(). In that situation, we |
// would still like to coalesce the gettimeofday() calls. |
- "6:cmp $224, %eax\n" // __NR_gettid |
- "jz 7f\n" |
+ "10:cmp $224, %eax\n" // __NR_gettid |
+ "jz 11f\n" |
"mov %eax, %fs:0x102C-0x58\n" // remember syscall number |
// Retrieve function call from system call table (c.f.system_call_table.cc) |
@@ -312,21 +324,24 @@ |
// that should be handled by the defaultSystemCallHandler(); minus one |
// for unrestricted system calls that need to be forwarded to the trusted |
// thread; and function pointers to specific handler functions. |
- "7:shl $3, %eax\n" |
- "mov playground$syscallTable, %ebx\n" |
- "add %ebx, %eax\n" |
+ "11:shl $3, %eax\n" |
+ "call 12f\n" |
+ "12:pop %ebx\n" |
+ "add $(_GLOBAL_OFFSET_TABLE_+(.-12b)), %ebx\n" |
+ "mov playground$syscallTable@GOT(%ebx), %ebx\n" |
+ "add 0(%ebx), %eax\n" |
"mov 0(%eax), %eax\n" |
// Jump to function if non-null and not UNRESTRICTED_SYSCALL, otherwise |
// jump to fallback handler. |
"cmp $1, %eax\n" |
- "jbe 9f\n" |
+ "jbe 14f\n" |
"add $4, %esp\n" |
"call *%eax\n" |
"add $24, %esp\n" |
// Restore CPU registers, except for %eax which was set by the system call. |
- "8:pop %esp\n" |
+ "13:pop %esp\n" |
"pop %edi\n" |
"pop %esi\n" |
"pop %edx\n" |
@@ -343,14 +358,13 @@ |
"ret\n" |
// Call default handler. |
- "9:call playground$defaultSystemCallHandler\n" |
- "10:add $28, %esp\n" |
- "jmp 8b\n" |
+ "14:call playground$defaultSystemCallHandler@PLT\n" |
+ "15:add $28, %esp\n" |
+ "jmp 13b\n" |
".pushsection \".bss\"\n" |
".balign 8\n" |
-"100:.byte 0, 0, 0, 0\n" |
-"101:.byte 0, 0, 0, 0\n" |
+"100:.byte 0, 0, 0, 0, 0, 0, 0, 0\n" |
".popsection\n" |
#else |