diff options
Diffstat (limited to 'common/recipes-kernel/linux/linux-yocto-4.9.21/0021-x86-entry-64-Remove-the-SYSCALL64-fast-path.patch')
| -rw-r--r-- | common/recipes-kernel/linux/linux-yocto-4.9.21/0021-x86-entry-64-Remove-the-SYSCALL64-fast-path.patch | 207 |
1 files changed, 0 insertions, 207 deletions
diff --git a/common/recipes-kernel/linux/linux-yocto-4.9.21/0021-x86-entry-64-Remove-the-SYSCALL64-fast-path.patch b/common/recipes-kernel/linux/linux-yocto-4.9.21/0021-x86-entry-64-Remove-the-SYSCALL64-fast-path.patch deleted file mode 100644 index c476da81..00000000 --- a/common/recipes-kernel/linux/linux-yocto-4.9.21/0021-x86-entry-64-Remove-the-SYSCALL64-fast-path.patch +++ /dev/null @@ -1,207 +0,0 @@ -From 18dacfea13d15dbf2fa1037cf76ee463c52af031 Mon Sep 17 00:00:00 2001 -From: Andy Lutomirski <luto@kernel.org> -Date: Sun, 28 Jan 2018 10:38:49 -0800 -Subject: [PATCH 21/42] x86/entry/64: Remove the SYSCALL64 fast path - -(cherry picked from commit 21d375b6b34ff511a507de27bf316b3dde6938d9) - -The SYCALLL64 fast path was a nice, if small, optimization back in the good -old days when syscalls were actually reasonably fast. Now there is PTI to -slow everything down, and indirect branches are verboten, making everything -messier. The retpoline code in the fast path is particularly nasty. - -Just get rid of the fast path. The slow path is barely slower. - -[ tglx: Split out the 'push all extra regs' part ] - -Signed-off-by: Andy Lutomirski <luto@kernel.org> -Signed-off-by: Thomas Gleixner <tglx@linutronix.de> -Acked-by: Ingo Molnar <mingo@kernel.org> -Cc: Borislav Petkov <bp@alien8.de> -Cc: Linus Torvalds <torvalds@linux-foundation.org> -Cc: Kernel Hardening <kernel-hardening@lists.openwall.com> -Link: https://lkml.kernel.org/r/462dff8d4d64dfbfc851fbf3130641809d980ecd.1517164461.git.luto@kernel.org -Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> -Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> ---- - arch/x86/entry/entry_64.S | 123 +------------------------------------------- - arch/x86/entry/syscall_64.c | 7 +-- - 2 files changed, 3 insertions(+), 127 deletions(-) - -diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S -index e422e15..4360253 100644 ---- a/arch/x86/entry/entry_64.S -+++ b/arch/x86/entry/entry_64.S -@@ -179,94 +179,11 @@ GLOBAL(entry_SYSCALL_64_after_swapgs) - pushq %r11 /* pt_regs->r11 */ - sub $(6*8), %rsp /* pt_regs->bp, bx, r12-15 not saved */ - -- /* -- * If we need to do entry work or if we guess we'll need to do -- * exit work, go straight to the slow path. -- */ -- movq PER_CPU_VAR(current_task), %r11 -- testl $_TIF_WORK_SYSCALL_ENTRY|_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) -- jnz entry_SYSCALL64_slow_path -- --entry_SYSCALL_64_fastpath: -- /* -- * Easy case: enable interrupts and issue the syscall. If the syscall -- * needs pt_regs, we'll call a stub that disables interrupts again -- * and jumps to the slow path. -- */ -- TRACE_IRQS_ON -- ENABLE_INTERRUPTS(CLBR_NONE) --#if __SYSCALL_MASK == ~0 -- cmpq $__NR_syscall_max, %rax --#else -- andl $__SYSCALL_MASK, %eax -- cmpl $__NR_syscall_max, %eax --#endif -- ja 1f /* return -ENOSYS (already in pt_regs->ax) */ -- movq %r10, %rcx -- -- /* -- * This call instruction is handled specially in stub_ptregs_64. -- * It might end up jumping to the slow path. If it jumps, RAX -- * and all argument registers are clobbered. -- */ --#ifdef CONFIG_RETPOLINE -- movq sys_call_table(, %rax, 8), %rax -- call __x86_indirect_thunk_rax --#else -- call *sys_call_table(, %rax, 8) --#endif --.Lentry_SYSCALL_64_after_fastpath_call: -- -- movq %rax, RAX(%rsp) --1: -- -- /* -- * If we get here, then we know that pt_regs is clean for SYSRET64. -- * If we see that no exit work is required (which we are required -- * to check with IRQs off), then we can go straight to SYSRET64. -- */ -- DISABLE_INTERRUPTS(CLBR_NONE) -- TRACE_IRQS_OFF -- movq PER_CPU_VAR(current_task), %r11 -- testl $_TIF_ALLWORK_MASK, TASK_TI_flags(%r11) -- jnz 1f -- -- LOCKDEP_SYS_EXIT -- TRACE_IRQS_ON /* user mode is traced as IRQs on */ -- movq RIP(%rsp), %rcx -- movq EFLAGS(%rsp), %r11 -- RESTORE_C_REGS_EXCEPT_RCX_R11 -- /* -- * This opens a window where we have a user CR3, but are -- * running in the kernel. This makes using the CS -- * register useless for telling whether or not we need to -- * switch CR3 in NMIs. Normal interrupts are OK because -- * they are off here. -- */ -- SWITCH_USER_CR3 -- movq RSP(%rsp), %rsp -- USERGS_SYSRET64 -- --1: -- /* -- * The fast path looked good when we started, but something changed -- * along the way and we need to switch to the slow path. Calling -- * raise(3) will trigger this, for example. IRQs are off. -- */ -- TRACE_IRQS_ON -- ENABLE_INTERRUPTS(CLBR_NONE) -- SAVE_EXTRA_REGS -- movq %rsp, %rdi -- call syscall_return_slowpath /* returns with IRQs disabled */ -- jmp return_from_SYSCALL_64 -- --entry_SYSCALL64_slow_path: - /* IRQs are off. */ - SAVE_EXTRA_REGS - movq %rsp, %rdi - call do_syscall_64 /* returns with IRQs disabled */ - --return_from_SYSCALL_64: - RESTORE_EXTRA_REGS - TRACE_IRQS_IRETQ /* we're about to change IF */ - -@@ -339,6 +256,7 @@ return_from_SYSCALL_64: - syscall_return_via_sysret: - /* rcx and r11 are already restored (see code above) */ - RESTORE_C_REGS_EXCEPT_RCX_R11 -+ - /* - * This opens a window where we have a user CR3, but are - * running in the kernel. This makes using the CS -@@ -363,45 +281,6 @@ opportunistic_sysret_failed: - jmp restore_c_regs_and_iret - END(entry_SYSCALL_64) - --ENTRY(stub_ptregs_64) -- /* -- * Syscalls marked as needing ptregs land here. -- * If we are on the fast path, we need to save the extra regs, -- * which we achieve by trying again on the slow path. If we are on -- * the slow path, the extra regs are already saved. -- * -- * RAX stores a pointer to the C function implementing the syscall. -- * IRQs are on. -- */ -- cmpq $.Lentry_SYSCALL_64_after_fastpath_call, (%rsp) -- jne 1f -- -- /* -- * Called from fast path -- disable IRQs again, pop return address -- * and jump to slow path -- */ -- DISABLE_INTERRUPTS(CLBR_NONE) -- TRACE_IRQS_OFF -- popq %rax -- jmp entry_SYSCALL64_slow_path -- --1: -- JMP_NOSPEC %rax /* Called from C */ --END(stub_ptregs_64) -- --.macro ptregs_stub func --ENTRY(ptregs_\func) -- leaq \func(%rip), %rax -- jmp stub_ptregs_64 --END(ptregs_\func) --.endm -- --/* Instantiate ptregs_stub for each ptregs-using syscall */ --#define __SYSCALL_64_QUAL_(sym) --#define __SYSCALL_64_QUAL_ptregs(sym) ptregs_stub sym --#define __SYSCALL_64(nr, sym, qual) __SYSCALL_64_QUAL_##qual(sym) --#include <asm/syscalls_64.h> -- - /* - * %rdi: prev task - * %rsi: next task -diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c -index 9dbc5ab..6705edd 100644 ---- a/arch/x86/entry/syscall_64.c -+++ b/arch/x86/entry/syscall_64.c -@@ -6,14 +6,11 @@ - #include <asm/asm-offsets.h> - #include <asm/syscall.h> - --#define __SYSCALL_64_QUAL_(sym) sym --#define __SYSCALL_64_QUAL_ptregs(sym) ptregs_##sym -- --#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long __SYSCALL_64_QUAL_##qual(sym)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); -+#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); - #include <asm/syscalls_64.h> - #undef __SYSCALL_64 - --#define __SYSCALL_64(nr, sym, qual) [nr] = __SYSCALL_64_QUAL_##qual(sym), -+#define __SYSCALL_64(nr, sym, qual) [nr] = sym, - - extern long sys_ni_syscall(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long); - --- -2.7.4 - |