mirror of
https://github.com/genodelabs/genode.git
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235 lines
7.0 KiB
Diff
235 lines
7.0 KiB
Diff
From f29031cdbe8cebf6c39d02a72dd50c736cec3a69 Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Jakub=20Jerm=C3=A1=C5=99?= <jakub.jermar@kernkonzept.com>
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Subject: [PATCH] amd64: Split _syscall_entry into code and data
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This change makes the entire syscall entry table smaller, sparing 32
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bytes per a statically configured CPU. Note that some padding is still
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used to achieve cacheline alignment of the per-CPU entries of the data
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part of the table.
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Furthemore, by moving the two data members into a data section and
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allowing to modify the handler offset from JDB only, the amd64 kernel is
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easier to make completely W^X in the future. The handler entry offset
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remains a part of the jump instruction opcode (there is no data
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indirection) and JDB is enhanced to be able to patch it when needed.
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Change-Id: I22b91f9fd2b108d99e3ceea6611a15ab3db26bb6
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Edit for Genode: UX changes not included because of more dependencies
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---
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src/jdb/ia32/jdb_trace_set-ia32-ux.cpp | 4 +-
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src/kern/ia32/64/cpu-64.cpp | 31 +++++-------------
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src/kern/ia32/64/entry.S | 29 +++++++++++++++++
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src/kern/ia32/64/syscall_entry.cpp | 54 +++++---------------------------
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4 files changed, 48 insertions(+), 70 deletions(-)
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diff --git a/src/jdb/ia32/jdb_trace_set-ia32-ux.cpp b/src/jdb/ia32/jdb_trace_set-ia32-ux.cpp
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index ec23322..0a2f309 100644
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--- a/src/jdb/ia32/jdb_trace_set-ia32-ux.cpp
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+++ b/src/jdb/ia32/jdb_trace_set-ia32-ux.cpp
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@@ -39,7 +39,7 @@ Jdb_set_trace::set_ipc_vector()
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Idt::set_entry(0x30, (Address) int30_entry, true);
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Jdb::on_each_cpu([fast_entry](Cpu_number cpu){
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- Cpu::cpus.cpu(cpu).set_fast_entry(fast_entry);
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+ //Cpu::cpus.cpu(cpu).set_fast_entry(fast_entry);
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});
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if (Jdb_ipc_trace::_trace)
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@@ -98,7 +98,7 @@ struct Jdb_ipc_log_pm : Pm_object
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else
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fast_entry = entry_sys_fast_ipc_c;
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- Cpu::cpus.cpu(cpu).set_fast_entry(fast_entry);
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+ //Cpu::cpus.cpu(cpu).set_fast_entry(fast_entry);
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}
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void pm_on_suspend(Cpu_number) override {}
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diff --git a/src/kern/ia32/64/cpu-64.cpp b/src/kern/ia32/64/cpu-64.cpp
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index 974c677..d18ad16 100644
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--- a/src/kern/ia32/64/cpu-64.cpp
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+++ b/src/kern/ia32/64/cpu-64.cpp
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@@ -4,7 +4,8 @@ INTERFACE [amd64 && !kernel_isolation]:
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EXTENSION class Cpu
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{
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- static Per_cpu_array<Syscall_entry> _syscall_entry;
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+ static Per_cpu_array<Syscall_entry_data>
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+ _syscall_entry_data asm("syscall_entry_data");
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};
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@@ -13,14 +14,7 @@ IMPLEMENTATION[amd64 && !kernel_isolation]:
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#include "mem_layout.h"
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#include "tss.h"
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-Per_cpu_array<Syscall_entry> Cpu::_syscall_entry;
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-
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-PUBLIC
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-void
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-Cpu::set_fast_entry(void (*func)())
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-{
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- _syscall_entry[id()].set_entry(func);
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-}
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+Per_cpu_array<Syscall_entry_data> Cpu::_syscall_entry_data;
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IMPLEMENT inline NEEDS["tss.h"]
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Address volatile &
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@@ -31,11 +25,13 @@ PUBLIC inline
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void
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Cpu::setup_sysenter()
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{
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+ extern Per_cpu_array<Syscall_entry_text> syscall_entry_text;
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+
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wrmsr(0, GDT_CODE_KERNEL | ((GDT_CODE_USER32 | 3) << 16), MSR_STAR);
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- wrmsr((Unsigned64)&_syscall_entry[id()], MSR_LSTAR);
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- wrmsr((Unsigned64)&_syscall_entry[id()], MSR_CSTAR);
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+ wrmsr((Unsigned64)&syscall_entry_text[id()], MSR_LSTAR);
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+ wrmsr((Unsigned64)&syscall_entry_text[id()], MSR_CSTAR);
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wrmsr(~0U, MSR_SFMASK);
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- _syscall_entry[id()].set_rsp((Address)&kernel_sp());
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+ _syscall_entry_data[id()].set_rsp((Address)&kernel_sp());
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}
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IMPLEMENTATION[amd64 && kernel_isolation]:
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@@ -43,16 +39,6 @@ IMPLEMENTATION[amd64 && kernel_isolation]:
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#include "mem_layout.h"
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#include "tss.h"
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-PUBLIC
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-void
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-Cpu::set_fast_entry(void (*func)())
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-{
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- extern char const syscall_entry_code[];
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- extern char const syscall_entry_reloc[];
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- auto ofs = syscall_entry_reloc - syscall_entry_code + 3; // 3 byte movebas
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- *reinterpret_cast<Signed32 *>(Mem_layout::Mem_layout::Kentry_cpu_page + ofs + 0xa0) = (Signed32)(Signed64)func;
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-}
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-
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PUBLIC inline
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void
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Cpu::setup_sysenter() const
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@@ -78,7 +64,6 @@ Cpu::init_sysenter()
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{
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setup_sysenter();
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wrmsr(rdmsr(MSR_EFER) | 1, MSR_EFER);
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- set_fast_entry(entry_sys_fast_ipc_c);
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}
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diff --git a/src/kern/ia32/64/entry.S b/src/kern/ia32/64/entry.S
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index 1cb8137..ed5a04c 100644
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--- a/src/kern/ia32/64/entry.S
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+++ b/src/kern/ia32/64/entry.S
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@@ -372,7 +372,36 @@ entry_\name:
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jmp all_syscalls
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.endm
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+#ifndef CONFIG_KERNEL_ISOLATION
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+#ifdef CONFIG_MP
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+MAX_NUM_CPUS = CONFIG_MP_MAX_CPUS
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+#else
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+MAX_NUM_CPUS = 1
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+#endif
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+
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+#define SYSCALL_ENTRY_DATA_SIZE 64
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+#define SYSCALL_ENTRY_TEXT_SIZE (0f - 0b)
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+#define SYSCALL_ENTRY_OFFSET ((0b - syscall_entry_text) / SYSCALL_ENTRY_TEXT_SIZE)
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+#define SYSCALL_ENTRY_DATA (syscall_entry_data + SYSCALL_ENTRY_OFFSET * SYSCALL_ENTRY_DATA_SIZE)
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+#define KERN_SP (SYSCALL_ENTRY_DATA + 0)
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+#define USER_SP (SYSCALL_ENTRY_DATA + 8)
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.section ".entry.text.syscalls", "ax", @progbits
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+ .global syscall_entry_text
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+ .align 64
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+syscall_entry_text:
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+.rept MAX_NUM_CPUS
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+0:
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+ mov %rsp, USER_SP(%rip)
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+ mov KERN_SP(%rip), %rsp
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+ mov (%rsp), %rsp
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+ pushq $GDT_DATA_USER | 3
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+ pushq USER_SP(%rip)
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+ jmp entry_sys_fast_ipc_c
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+ .align 32
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+0:
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+.endr
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+#endif /* !CONFIG_KERNEL_ISOLATION */
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+
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.p2align 4
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.type all_syscalls,@function
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all_syscalls:
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diff --git a/src/kern/ia32/64/syscall_entry.cpp b/src/kern/ia32/64/syscall_entry.cpp
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index b03d1ad..3dd7db3 100644
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--- a/src/kern/ia32/64/syscall_entry.cpp
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+++ b/src/kern/ia32/64/syscall_entry.cpp
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@@ -2,58 +2,22 @@ INTERFACE [amd64]:
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#include "types.h"
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-class Syscall_entry
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+class Syscall_entry_data
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{
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-private:
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- template<int INSN_LEN>
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- struct Mem_insn
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- {
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- Unsigned32 _insn:INSN_LEN * 8;
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- Unsigned32 _offset;
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- Mem_insn(Unsigned32 insn, void *mem)
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- : _insn(insn),
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- _offset((Address)mem - (Address)(&_offset + 1))
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- {}
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- } __attribute__((packed));
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-
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- Mem_insn<3> _mov_rsp_user_sp;
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- Mem_insn<3> _mov_kern_sp_rsp;
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- Unsigned32 _mov_rsp_rsp;
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- Unsigned8 _push_ss, _ss_value;
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- Mem_insn<2> _push_user_rsp;
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- Unsigned8 _jmp;
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- Signed32 _entry_offset;
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- Unsigned8 _pading[33]; // pad to the next 64 byte boundary
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- Unsigned64 _kern_sp;
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- Unsigned64 _user_sp;
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-} __attribute__((packed, aligned(64)));
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+ Unsigned64 _kern_sp = 0;
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+ Unsigned64 _user_sp = 0;
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+} __attribute__((packed, aligned(64))); // Enforce cacheline alignment
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+struct Syscall_entry_text
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+{
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+ char _res[32]; // Keep this in sync with code in syscall_entry_text!
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+} __attribute__((packed, aligned(32)));
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IMPLEMENTATION [amd64]:
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-#include "config_gdt.h"
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-
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-PUBLIC inline NEEDS["config_gdt.h"]
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-Syscall_entry::Syscall_entry()
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-: /* mov %rsp, _user_sp(%rip) */ _mov_rsp_user_sp(0x258948, &_user_sp),
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- /* mov _kern_sp(%rip), %rsp */ _mov_kern_sp_rsp(0x258b48, &_kern_sp),
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- /* mov (%rsp), %rsp */ _mov_rsp_rsp(0x24248b48),
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- /* pushq GDT_DATA_USER | 3 */ _push_ss(0x6a), _ss_value(GDT_DATA_USER | 3),
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- /* pushq _user_sp(%rip) */ _push_user_rsp(0x35ff, &_user_sp),
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- /* jmp *_entry_offset */ _jmp(0xe9)
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-{}
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-
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-PUBLIC inline
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-void
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-Syscall_entry::set_entry(void (*func)(void))
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-{
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- _entry_offset = (Address)func
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- - ((Address)&_entry_offset + sizeof(_entry_offset));
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-}
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-
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PUBLIC inline
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void
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-Syscall_entry::set_rsp(Address rsp)
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+Syscall_entry_data::set_rsp(Address rsp)
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{
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_kern_sp = rsp;
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}
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