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| author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2018-03-05 07:39:06 -0500 |
|---|---|---|
| committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2018-03-05 07:39:06 -0500 |
| commit | 76bf7087fb2118aee16370821975f8a58febf68a (patch) | |
| tree | c1a110c82b60b400dd5ac94c73317b284f0a19dc /arch/x86/lib/retpoline.S | |
| parent | e3e389f931a14ddf43089c7db92fc5d74edf93a4 (diff) | |
| parent | 661e50bc853209e41a5c14a290ca4decc43cbfd1 (diff) | |
| download | linux-76bf7087fb2118aee16370821975f8a58febf68a.tar.gz linux-76bf7087fb2118aee16370821975f8a58febf68a.tar.xz | |
Merge commit 'v4.16-rc4~0' into patchwork
* commit 'v4.16-rc4~0': (900 commits)
Linux 4.16-rc4
memremap: fix softlockup reports at teardown
libnvdimm: re-enable deep flush for pmem devices via fsync()
MAINTAINERS: take over Kconfig maintainership
vfio: disable filesystem-dax page pinning
kconfig: fix line number in recursive inclusion error message
Coccinelle: memdup: Fix typo in warning messages
i2c: octeon: Prevent error message on bus error
parisc: Reduce irq overhead when run in qemu
parisc: Use cr16 interval timers unconditionally on qemu
parisc: Check if secondary CPUs want own PDC calls
parisc: Hide virtual kernel memory layout
parisc: Fix ordering of cache and TLB flushes
kconfig: Update ncurses package names for menuconfig
kbuild/kallsyms: trivial typo fix
kbuild: test --build-id linker flag by ld-option instead of cc-ldoption
kbuild: drop superfluous GCC_PLUGINS_CFLAGS assignment
kconfig: Don't leak choice names during parsing
sh: fix build error for empty CONFIG_BUILTIN_DTB_SOURCE
kconfig: set SYMBOL_AUTO to the symbol marked with defconfig_list
...
Diffstat (limited to 'arch/x86/lib/retpoline.S')
| -rw-r--r-- | arch/x86/lib/retpoline.S | 56 |
1 files changed, 0 insertions, 56 deletions
diff --git a/arch/x86/lib/retpoline.S b/arch/x86/lib/retpoline.S index 480edc3a5e03..c909961e678a 100644 --- a/arch/x86/lib/retpoline.S +++ b/arch/x86/lib/retpoline.S @@ -7,7 +7,6 @@ #include <asm/alternative-asm.h> #include <asm/export.h> #include <asm/nospec-branch.h> -#include <asm/bitsperlong.h> .macro THUNK reg .section .text.__x86.indirect_thunk @@ -47,58 +46,3 @@ GENERATE_THUNK(r13) GENERATE_THUNK(r14) GENERATE_THUNK(r15) #endif - -/* - * Fill the CPU return stack buffer. - * - * Each entry in the RSB, if used for a speculative 'ret', contains an - * infinite 'pause; lfence; jmp' loop to capture speculative execution. - * - * This is required in various cases for retpoline and IBRS-based - * mitigations for the Spectre variant 2 vulnerability. Sometimes to - * eliminate potentially bogus entries from the RSB, and sometimes - * purely to ensure that it doesn't get empty, which on some CPUs would - * allow predictions from other (unwanted!) sources to be used. - * - * Google experimented with loop-unrolling and this turned out to be - * the optimal version - two calls, each with their own speculation - * trap should their return address end up getting used, in a loop. - */ -.macro STUFF_RSB nr:req sp:req - mov $(\nr / 2), %_ASM_BX - .align 16 -771: - call 772f -773: /* speculation trap */ - pause - lfence - jmp 773b - .align 16 -772: - call 774f -775: /* speculation trap */ - pause - lfence - jmp 775b - .align 16 -774: - dec %_ASM_BX - jnz 771b - add $((BITS_PER_LONG/8) * \nr), \sp -.endm - -#define RSB_FILL_LOOPS 16 /* To avoid underflow */ - -ENTRY(__fill_rsb) - STUFF_RSB RSB_FILL_LOOPS, %_ASM_SP - ret -END(__fill_rsb) -EXPORT_SYMBOL_GPL(__fill_rsb) - -#define RSB_CLEAR_LOOPS 32 /* To forcibly overwrite all entries */ - -ENTRY(__clear_rsb) - STUFF_RSB RSB_CLEAR_LOOPS, %_ASM_SP - ret -END(__clear_rsb) -EXPORT_SYMBOL_GPL(__clear_rsb) |