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libc: Add ftruncate64 and improve 64-bit parameter syscall handling.

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This patch improves the handling of 64-bit parameters in syscalls on ARM.
The ARM EABI mandates that 64-bit quantities be passed in even/odd register
pairs, which requires special treatment.

This allows us to simplify our implementations of pread() and pwrite()
and remove the C stubs for pread64() and pwrite64().

Also add ftruncate64() to <unistd.h>

Change-Id: I407e2fd223ba0093dd2d0b04c6152fadfc9ce3ef

Bug 3107933
This commit is contained in:
David 'Digit' Turner
2010-12-16 16:47:14 +01:00
parent 4a7f31fad7
commit 95d751feac
23 changed files with 181 additions and 116 deletions
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68
libc/tools/gensyscalls.py
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@@ -245,6 +245,59 @@ superh_7args_header = """
"""
def param_uses_64bits(param):
"""Returns True iff a syscall parameter description corresponds
to a 64-bit type."""
param = param.strip()
# First, check that the param type begins with one of the known
# 64-bit types.
if not ( \
param.startswith("int64_t") or param.startswith("uint64_t") or \
param.startswith("loff_t") or param.startswith("off64_t") or \
param.startswith("long long") or param.startswith("unsigned long long") or
param.startswith("signed long long") ):
return False
# Second, check that there is no pointer type here
if param.find("*") >= 0:
return False
# Ok
return True
def count_arm_param_registers(params):
"""This function is used to count the number of register used
to pass parameters when invoking a thumb or ARM system call.
This is because the ARM EABI mandates that 64-bit quantities
must be passed in an even+odd register pair. So, for example,
something like:
foo(int fd, off64_t pos)
would actually need 4 registers:
r0 -> int
r1 -> unused
r2-r3 -> pos
"""
count = 0
for param in params:
if param_uses_64bits(param):
if (count & 1) != 0:
count += 1
count += 2
else:
count += 1
return count
def count_generic_param_registers(params):
count = 0
for param in params:
if param_uses_64bits(param):
count += 2
else:
count += 1
return count
class State:
def __init__(self):
self.old_stubs = []
@@ -370,25 +423,28 @@ class State:
syscall_name = t["name"]
if t["id"] >= 0:
num_regs = count_arm_param_registers(syscall_params)
if gen_thumb_stubs:
t["asm-thumb"] = self.thumb_genstub(syscall_func,len(syscall_params),"__NR_"+syscall_name)
t["asm-thumb"] = self.thumb_genstub(syscall_func,num_regs,"__NR_"+syscall_name)
else:
if gen_eabi_stubs:
t["asm-arm"] = self.arm_eabi_genstub(syscall_func,len(syscall_params),"__NR_"+syscall_name)
t["asm-arm"] = self.arm_eabi_genstub(syscall_func,num_regs,"__NR_"+syscall_name)
else:
t["asm-arm"] = self.arm_genstub(syscall_func,len(syscall_params),"__NR_"+syscall_name)
t["asm-arm"] = self.arm_genstub(syscall_func,num_regs,"__NR_"+syscall_name)
if t["id2"] >= 0:
num_regs = count_generic_param_registers(syscall_params)
if t["cid"] >= 0:
t["asm-x86"] = self.x86_genstub_cid(syscall_func, len(syscall_params), "__NR_"+syscall_name, t["cid"])
t["asm-x86"] = self.x86_genstub_cid(syscall_func, num_regs, "__NR_"+syscall_name, t["cid"])
else:
t["asm-x86"] = self.x86_genstub(syscall_func,len(syscall_params),"__NR_"+syscall_name)
t["asm-x86"] = self.x86_genstub(syscall_func, num_regs, "__NR_"+syscall_name)
elif t["cid"] >= 0:
E("cid for dispatch syscalls is only supported for x86 in "
"'%s'" % syscall_name)
return
if t["id3"] >= 0:
t["asm-sh"] = self.superh_genstub(syscall_func,len(syscall_params),"__NR_"+syscall_name)
num_regs = count_generic_param_registers(syscall_params)
t["asm-sh"] = self.superh_genstub(syscall_func,num_regs,"__NR_"+syscall_name)