wireguard-linux/arch/x86/include/asm/syscall.h, branch update-toolchain

x86/bhi: Add support for clearing branch history at syscall entry

2024-04-08T17:27:05Z

Branch History Injection (BHI) attacks may allow a malicious application to influence indirect branch prediction in kernel by poisoning the branch history. eIBRS isolates indirect branch targets in ring0. The BHB can still influence the choice of indirect branch predictor entry, and although branch predictor entries are isolated between modes when eIBRS is enabled, the BHB itself is not isolated between modes. Alder Lake and new processors supports a hardware control BHI_DIS_S to mitigate BHI. For older processors Intel has released a software sequence to clear the branch history on parts that don't support BHI_DIS_S. Add support to execute the software sequence at syscall entry and VMexit to overwrite the branch history. For now, branch history is not cleared at interrupt entry, as malicious applications are not believed to have sufficient control over the registers, since previous register state is cleared at interrupt entry. Researchers continue to poke at this area and it may become necessary to clear at interrupt entry as well in the future. This mitigation is only defined here. It is enabled later. Signed-off-by: Pawan Gupta Co-developed-by: Daniel Sneddon Signed-off-by: Daniel Sneddon Signed-off-by: Thomas Gleixner Reviewed-by: Alexandre Chartre Reviewed-by: Josh Poimboeuf

x86/syscall: Don't force use of indirect calls for system calls

2024-04-08T17:27:05Z

Make build a switch statement instead, and the compiler can either decide to generate an indirect jump, or - more likely these days due to mitigations - just a series of conditional branches. Yes, the conditional branches also have branch prediction, but the branch prediction is much more controlled, in that it just causes speculatively running the wrong system call (harmless), rather than speculatively running possibly wrong random less controlled code gadgets. This doesn't mitigate other indirect calls, but the system call indirection is the first and most easily triggered case. Signed-off-by: Linus Torvalds Signed-off-by: Daniel Sneddon Signed-off-by: Thomas Gleixner Reviewed-by: Josh Poimboeuf

x86/entry/64: Convert SYSRET validation tests to C

2023-10-13T11:05:28Z

No change in functionality expected. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Josh Poimboeuf Cc: Uros Bizjak Link: https://lore.kernel.org/r/20231011224351.130935-2-brgerst@gmail.com

x86/entry/32: Convert do_fast_syscall_32() to bool return type

2023-10-05T08:06:42Z

Doesn't have to be 'long' - this simplifies the code a bit. Signed-off-by: Brian Gerst Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20230721161018.50214-5-brgerst@gmail.com

x86/entry: Add do_SYSENTER_32() prototype

2023-05-18T18:56:18Z

The 32-bit system call entry points can be called on both 32-bit and 64-bit kernels, but on the former the declarations are hidden: arch/x86/entry/common.c:238:24: error: no previous prototype for 'do_SYSENTER_32' [-Werror=missing-prototypes] Move them all out of the #ifdef block to avoid the warnings. Signed-off-by: Arnd Bergmann Signed-off-by: Dave Hansen Reviewed-by: Alexander Lobakin Link: https://lore.kernel.org/all/20230516193549.544673-12-arnd%40kernel.org

arch: remove unused function syscall_set_arguments()

2021-09-14T14:06:20Z

This function appears to have been unused since it was first introduced in commit 828c365cc8b8 ("tracehook: asm/syscall.h"). Signed-off-by: Peter Collingbourne Link: https://linux-review.googlesource.com/id/I8ce04f002903a37c0b6c1d16e9b2a3afa716c097 Signed-off-by: Arnd Bergmann

x86/entry: Use int everywhere for system call numbers

2021-05-25T08:07:00Z

System call numbers are defined as int, so use int everywhere for system call numbers. This is strictly a cleanup; it should not change anything user visible; all ABI changes have been done in the preceeding patches. [ tglx: Replaced the unsigned long cast ] Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210518191303.4135296-7-hpa@zytor.com

x86/syscall: Unconditionally prototype {ia32,x32}_sys_call_table[]

2021-05-12T08:49:15Z

Even if these APIs are disabled, and the arrays therefore do not exist, having the prototypes allows us to use IS_ENABLED() rather than using #ifdefs. If something ends up trying to actually *use* these arrays a linker error will ensue. Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210510185316.3307264-4-hpa@zytor.com

x86/entry: Reverse arguments to do_syscall_64()

2021-05-12T08:49:14Z

Reverse the order of arguments to do_syscall_64() so that the first argument is the pt_regs pointer. This is not only consistent with *all* other entry points from assembly, but it actually makes the compiled code slightly better. Signed-off-by: H. Peter Anvin (Intel) Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/20210510185316.3307264-3-hpa@zytor.com

Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2020-03-31T18:04:05Z

Pull x86 cleanups from Ingo Molnar: "This topic tree contains more commits than usual: - most of it are uaccess cleanups/reorganization by Al - there's a bunch of prototype declaration (--Wmissing-prototypes) cleanups - misc other cleanups all around the map" * 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (36 commits) x86/mm/set_memory: Fix -Wmissing-prototypes warnings x86/efi: Add a prototype for efi_arch_mem_reserve() x86/mm: Mark setup_emu2phys_nid() static x86/jump_label: Move 'inline' keyword placement x86/platform/uv: Add a missing prototype for uv_bau_message_interrupt() kill uaccess_try() x86: unsafe_put-style macro for sigmask x86: x32_setup_rt_frame(): consolidate uaccess areas x86: __setup_rt_frame(): consolidate uaccess areas x86: __setup_frame(): consolidate uaccess areas x86: setup_sigcontext(): list user_access_{begin,end}() into callers x86: get rid of put_user_try in __setup_rt_frame() (both 32bit and 64bit) x86: ia32_setup_rt_frame(): consolidate uaccess areas x86: ia32_setup_frame(): consolidate uaccess areas x86: ia32_setup_sigcontext(): lift user_access_{begin,end}() into the callers x86/alternatives: Mark text_poke_loc_init() static x86/cpu: Fix a -Wmissing-prototypes warning for init_ia32_feat_ctl() x86/mm: Drop pud_mknotpresent() x86: Replace setup_irq() by request_irq() x86/configs: Slightly reduce defconfigs ...