From: Nadav Har'El <[email protected]>
Committer: Nadav Har'El <[email protected]>
Branch: master
syscall: fix indentation mishmash in entry.S
No functional changes.
Signed-off-by: Nadav Har'El <[email protected]>
Message-Id: <[email protected]>
---
diff --git a/arch/x64/entry.S b/arch/x64/entry.S
--- a/arch/x64/entry.S
+++ b/arch/x64/entry.S
@@ -162,9 +162,13 @@ call_signal_handler_thunk:
.align 16
.global syscall_entry
syscall_entry:
- .type syscall_entry, @function
- .cfi_startproc simple
- # There is no ring transition and rflags are left unchanged.
+ .type syscall_entry, @function
+ .cfi_startproc simple
+ # There is no ring transition and rflags are left unchanged.
+
+ # Skip the "red zone" allowed by the AMD64 ABI (the caller used a
+ # SYSCALL instruction and doesn't know he called a function):
+ subq $128, %rsp
# Skip the "red zone" allowed by the AMD64 ABI (the caller used a
# SYSCALL instruction and doesn't know he called a function):
@@ -177,68 +181,68 @@ syscall_entry:
pushq %rcx
pushq %rbp
movq %rsp, %rbp
- #
- # From
http://stackoverflow.com/questions/2535989/what-are-the-calling-conventions-for-unix-linux-system-calls-on-x86-64:
- # "User-level applications use as integer registers for passing the
sequence %rdi, %rsi, %rdx, %rcx, %r8 and %r9. The kernel interface
uses %rdi, %rsi, %rdx, %r10, %r8 and %r9"
+ #
+ # From
http://stackoverflow.com/questions/2535989/what-are-the-calling-conventions-for-unix-linux-system-calls-on-x86-64:
+ # "User-level applications use as integer registers for passing the
sequence %rdi, %rsi, %rdx, %rcx, %r8 and %r9. The kernel interface
uses %rdi, %rsi, %rdx, %r10, %r8 and %r9"
- # FIXME: fpu
- # build the stack frame by hand
- pushq %rsp
- subq $8, %rsp # rip was saved in rcx by the syscall instruction
- pushq %rax
- pushq %rbx
- pushq %rcx # contains rip before syscall instruction
- pushq %rdx
- pushq %rsi
- pushq %rdi
- pushq %r8
- pushq %r9
- pushq %r10
- pushq %r11 # contains rflags before syscall instruction
- pushq %r12
- pushq %r13
- pushq %r14
- pushq %r15
+ # FIXME: fpu
+ # build the stack frame by hand
+ pushq %rsp
+ subq $8, %rsp # rip was saved in rcx by the syscall instruction
+ pushq %rax
+ pushq %rbx
+ pushq %rcx # contains rip before syscall instruction
+ pushq %rdx
+ pushq %rsi
+ pushq %rdi
+ pushq %r8
+ pushq %r9
+ pushq %r10
+ pushq %r11 # contains rflags before syscall instruction
+ pushq %r12
+ pushq %r13
+ pushq %r14
+ pushq %r15
- # stack contains a signal_frame
- .cfi_signal_frame
- .cfi_def_cfa %rsp, 0
+ # stack contains a signal_frame
+ .cfi_signal_frame
+ .cfi_def_cfa %rsp, 0
.cfi_register rip,rcx # rcx took previous rip value
.cfi_register rflags,r11 # r11 took previous rflags value
.cfi_undefined rcx # was overwritten with rip by the syscall instruction
.cfi_undefined r11 # was overwritten with rflags by the syscall
instruction
- .cfi_offset %r15, 0x00
- .cfi_offset %r14, 0x08
- .cfi_offset %r13, 0x10
- .cfi_offset %r12, 0x18
- .cfi_offset %r11, 0x20
- .cfi_offset %r10, 0x28
- .cfi_offset %r9, 0x30
- .cfi_offset %r8, 0x38
- .cfi_offset %rbp, 0x40
- .cfi_offset %rdi, 0x48
- .cfi_offset %rsi, 0x50
- .cfi_offset %rdx, 0x58
- .cfi_offset %rcx, 0x60
- .cfi_offset %rbx, 0x68
- .cfi_offset %rax, 0x70
- .cfi_offset %rip, 0x80
- .cfi_offset %rsp, 0x98
+ .cfi_offset %r15, 0x00
+ .cfi_offset %r14, 0x08
+ .cfi_offset %r13, 0x10
+ .cfi_offset %r12, 0x18
+ .cfi_offset %r11, 0x20
+ .cfi_offset %r10, 0x28
+ .cfi_offset %r9, 0x30
+ .cfi_offset %r8, 0x38
+ .cfi_offset %rbp, 0x40
+ .cfi_offset %rdi, 0x48
+ .cfi_offset %rsi, 0x50
+ .cfi_offset %rdx, 0x58
+ .cfi_offset %rcx, 0x60
+ .cfi_offset %rbx, 0x68
+ .cfi_offset %rax, 0x70
+ .cfi_offset %rip, 0x80
+ .cfi_offset %rsp, 0x98
- # The kernel interface use r10 as fourth argument while the user
interface use rcx
- # so overwrite rcx with r10
- movq %r10, %rcx
+ # The kernel interface use r10 as fourth argument while the user
interface use rcx
+ # so overwrite rcx with r10
+ movq %r10, %rcx
- # prepare function call parameter: r9 is on the stack since it's the
seventh param
- # because we shift existing params by one to make room for syscall
number
- pushq %r9
- movq %r8, %r9
- movq %rcx, %r8
- movq %rdx, %rcx
- movq %rsi, %rdx
- movq %rdi, %rsi
- # syscall number from rax as first argument
- movq %rax, %rdi
+ # prepare function call parameter: r9 is on the stack since it's the
seventh param
+ # because we shift existing params by one to make room for syscall
number
+ pushq %r9
+ movq %r8, %r9
+ movq %rcx, %r8
+ movq %rdx, %rcx
+ movq %rsi, %rdx
+ movq %rdi, %rsi
+ # syscall number from rax as first argument
+ movq %rax, %rdi
# align stack to 16 bytes, as required by the ABI.
# Counting the pushes above is not enough because we don't know what
was
@@ -256,37 +260,37 @@ syscall_entry:
pushq (%rsp)
andq $-0x10, %rsp
- callq syscall_wrapper
+ callq syscall_wrapper
movq 8(%rsp), %rsp
- popq %r9
- # in Linux user and kernel return value are in rax so we have nothing to
do for return values
+ popq %r9
+ # in Linux user and kernel return value are in rax so we have nothing
to do for return values
- popq %r15
- popq %r14
- popq %r13
- popq %r12
- popq %r11
- popq %r10
- popq %r9
- popq %r8
- popq %rdi
- popq %rsi
- popq %rdx
- popq %rcx
- popq %rbx
- addq $8, %rsp # skip rax emplacement (return value is in rax)
- addq $8, %rsp # rip emplacement (rip cannot be popped)
- popq %rsp
+ popq %r15
+ popq %r14
+ popq %r13
+ popq %r12
+ popq %r11
+ popq %r10
+ popq %r9
+ popq %r8
+ popq %rdi
+ popq %rsi
+ popq %rdx
+ popq %rcx
+ popq %rbx
+ addq $8, %rsp # skip rax emplacement (return value is in rax)
+ addq $8, %rsp # rip emplacement (rip cannot be popped)
+ popq %rsp
popq %rbp
popq %rcx
addq $128, %rsp # undo red-zone skip
- # jump to rcx where the syscall instruction put rip
- # (sysret would leave rxc cloberred so we have nothing to do to restore
it)
- jmpq *%rcx
- .cfi_endproc
+ # jump to rcx where the syscall instruction put rip
+ # (sysret would leave rxc cloberred so we have nothing to do to
restore it)
+ jmpq *%rcx
+ .cfi_endproc
.size syscall_entry, .-syscall_entry
--
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