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authorWill Deacon <will@kernel.org>2022-03-14 22:05:13 +0300
committerWill Deacon <will@kernel.org>2022-03-14 22:08:31 +0300
commit641d804157294d9b19bdfe6a2cdbd5d25939a048 (patch)
treed4e06201998b94999fc1e1ea7cea95b334da9630 /arch/arm64/kernel/entry.S
parent8d93b7a242b2adf36949c10b8eb9cc084a74b59a (diff)
parent52c9f93a9c482251cb0d224faa602ba26d462be8 (diff)
downloadlinux-641d804157294d9b19bdfe6a2cdbd5d25939a048.tar.xz
Merge branch 'for-next/spectre-bhb' into for-next/core
Merge in the latest Spectre mess to fix up conflicts with what was already queued for 5.18 when the embargo finally lifted. * for-next/spectre-bhb: (21 commits) arm64: Do not include __READ_ONCE() block in assembly files arm64: proton-pack: Include unprivileged eBPF status in Spectre v2 mitigation reporting arm64: Use the clearbhb instruction in mitigations KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated arm64: Mitigate spectre style branch history side channels arm64: proton-pack: Report Spectre-BHB vulnerabilities as part of Spectre-v2 arm64: Add percpu vectors for EL1 arm64: entry: Add macro for reading symbol addresses from the trampoline arm64: entry: Add vectors that have the bhb mitigation sequences arm64: entry: Add non-kpti __bp_harden_el1_vectors for mitigations arm64: entry: Allow the trampoline text to occupy multiple pages arm64: entry: Make the kpti trampoline's kpti sequence optional arm64: entry: Move trampoline macros out of ifdef'd section arm64: entry: Don't assume tramp_vectors is the start of the vectors arm64: entry: Allow tramp_alias to access symbols after the 4K boundary arm64: entry: Move the trampoline data page before the text page arm64: entry: Free up another register on kpti's tramp_exit path arm64: entry: Make the trampoline cleanup optional KVM: arm64: Allow indirect vectors to be used without SPECTRE_V3A arm64: spectre: Rename spectre_v4_patch_fw_mitigation_conduit ...
Diffstat (limited to 'arch/arm64/kernel/entry.S')
-rw-r--r--arch/arm64/kernel/entry.S214
1 files changed, 157 insertions, 57 deletions
diff --git a/arch/arm64/kernel/entry.S b/arch/arm64/kernel/entry.S
index a3ee79bcd5cb..ede028dee81b 100644
--- a/arch/arm64/kernel/entry.S
+++ b/arch/arm64/kernel/entry.S
@@ -37,18 +37,21 @@
.macro kernel_ventry, el:req, ht:req, regsize:req, label:req
.align 7
-#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+.Lventry_start\@:
.if \el == 0
-alternative_if ARM64_UNMAP_KERNEL_AT_EL0
+ /*
+ * This must be the first instruction of the EL0 vector entries. It is
+ * skipped by the trampoline vectors, to trigger the cleanup.
+ */
+ b .Lskip_tramp_vectors_cleanup\@
.if \regsize == 64
mrs x30, tpidrro_el0
msr tpidrro_el0, xzr
.else
mov x30, xzr
.endif
-alternative_else_nop_endif
+.Lskip_tramp_vectors_cleanup\@:
.endif
-#endif
sub sp, sp, #PT_REGS_SIZE
#ifdef CONFIG_VMAP_STACK
@@ -95,11 +98,15 @@ alternative_else_nop_endif
mrs x0, tpidrro_el0
#endif
b el\el\ht\()_\regsize\()_\label
+.org .Lventry_start\@ + 128 // Did we overflow the ventry slot?
.endm
- .macro tramp_alias, dst, sym
+ .macro tramp_alias, dst, sym, tmp
mov_q \dst, TRAMP_VALIAS
- add \dst, \dst, #(\sym - .entry.tramp.text)
+ adr_l \tmp, \sym
+ add \dst, \dst, \tmp
+ adr_l \tmp, .entry.tramp.text
+ sub \dst, \dst, \tmp
.endm
/*
@@ -116,7 +123,7 @@ alternative_cb_end
tbnz \tmp2, #TIF_SSBD, .L__asm_ssbd_skip\@
mov w0, #ARM_SMCCC_ARCH_WORKAROUND_2
mov w1, #\state
-alternative_cb spectre_v4_patch_fw_mitigation_conduit
+alternative_cb smccc_patch_fw_mitigation_conduit
nop // Patched to SMC/HVC #0
alternative_cb_end
.L__asm_ssbd_skip\@:
@@ -410,21 +417,26 @@ alternative_else_nop_endif
ldp x24, x25, [sp, #16 * 12]
ldp x26, x27, [sp, #16 * 13]
ldp x28, x29, [sp, #16 * 14]
- ldr lr, [sp, #S_LR]
- add sp, sp, #PT_REGS_SIZE // restore sp
.if \el == 0
-alternative_insn eret, nop, ARM64_UNMAP_KERNEL_AT_EL0
+alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
+ ldr lr, [sp, #S_LR]
+ add sp, sp, #PT_REGS_SIZE // restore sp
+ eret
+alternative_else_nop_endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
bne 4f
- msr far_el1, x30
- tramp_alias x30, tramp_exit_native
+ msr far_el1, x29
+ tramp_alias x30, tramp_exit_native, x29
br x30
4:
- tramp_alias x30, tramp_exit_compat
+ tramp_alias x30, tramp_exit_compat, x29
br x30
#endif
.else
+ ldr lr, [sp, #S_LR]
+ add sp, sp, #PT_REGS_SIZE // restore sp
+
/* Ensure any device/NC reads complete */
alternative_insn nop, "dmb sy", ARM64_WORKAROUND_1508412
@@ -591,12 +603,6 @@ SYM_CODE_END(ret_to_user)
.popsection // .entry.text
-#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
-/*
- * Exception vectors trampoline.
- */
- .pushsection ".entry.tramp.text", "ax"
-
// Move from tramp_pg_dir to swapper_pg_dir
.macro tramp_map_kernel, tmp
mrs \tmp, ttbr1_el1
@@ -630,12 +636,47 @@ alternative_else_nop_endif
*/
.endm
- .macro tramp_ventry, regsize = 64
+ .macro tramp_data_page dst
+ adr_l \dst, .entry.tramp.text
+ sub \dst, \dst, PAGE_SIZE
+ .endm
+
+ .macro tramp_data_read_var dst, var
+#ifdef CONFIG_RANDOMIZE_BASE
+ tramp_data_page \dst
+ add \dst, \dst, #:lo12:__entry_tramp_data_\var
+ ldr \dst, [\dst]
+#else
+ ldr \dst, =\var
+#endif
+ .endm
+
+#define BHB_MITIGATION_NONE 0
+#define BHB_MITIGATION_LOOP 1
+#define BHB_MITIGATION_FW 2
+#define BHB_MITIGATION_INSN 3
+
+ .macro tramp_ventry, vector_start, regsize, kpti, bhb
.align 7
1:
.if \regsize == 64
msr tpidrro_el0, x30 // Restored in kernel_ventry
.endif
+
+ .if \bhb == BHB_MITIGATION_LOOP
+ /*
+ * This sequence must appear before the first indirect branch. i.e. the
+ * ret out of tramp_ventry. It appears here because x30 is free.
+ */
+ __mitigate_spectre_bhb_loop x30
+ .endif // \bhb == BHB_MITIGATION_LOOP
+
+ .if \bhb == BHB_MITIGATION_INSN
+ clearbhb
+ isb
+ .endif // \bhb == BHB_MITIGATION_INSN
+
+ .if \kpti == 1
/*
* Defend against branch aliasing attacks by pushing a dummy
* entry onto the return stack and using a RET instruction to
@@ -645,46 +686,75 @@ alternative_else_nop_endif
b .
2:
tramp_map_kernel x30
-#ifdef CONFIG_RANDOMIZE_BASE
- adr x30, tramp_vectors + PAGE_SIZE
alternative_insn isb, nop, ARM64_WORKAROUND_QCOM_FALKOR_E1003
- ldr x30, [x30]
-#else
- ldr x30, =vectors
-#endif
+ tramp_data_read_var x30, vectors
alternative_if_not ARM64_WORKAROUND_CAVIUM_TX2_219_PRFM
- prfm plil1strm, [x30, #(1b - tramp_vectors)]
+ prfm plil1strm, [x30, #(1b - \vector_start)]
alternative_else_nop_endif
+
msr vbar_el1, x30
- add x30, x30, #(1b - tramp_vectors)
isb
+ .else
+ ldr x30, =vectors
+ .endif // \kpti == 1
+
+ .if \bhb == BHB_MITIGATION_FW
+ /*
+ * The firmware sequence must appear before the first indirect branch.
+ * i.e. the ret out of tramp_ventry. But it also needs the stack to be
+ * mapped to save/restore the registers the SMC clobbers.
+ */
+ __mitigate_spectre_bhb_fw
+ .endif // \bhb == BHB_MITIGATION_FW
+
+ add x30, x30, #(1b - \vector_start + 4)
ret
+.org 1b + 128 // Did we overflow the ventry slot?
.endm
.macro tramp_exit, regsize = 64
- adr x30, tramp_vectors
+ tramp_data_read_var x30, this_cpu_vector
+ get_this_cpu_offset x29
+ ldr x30, [x30, x29]
+
msr vbar_el1, x30
- tramp_unmap_kernel x30
+ ldr lr, [sp, #S_LR]
+ tramp_unmap_kernel x29
.if \regsize == 64
- mrs x30, far_el1
+ mrs x29, far_el1
.endif
+ add sp, sp, #PT_REGS_SIZE // restore sp
eret
sb
.endm
- .align 11
-SYM_CODE_START_NOALIGN(tramp_vectors)
+ .macro generate_tramp_vector, kpti, bhb
+.Lvector_start\@:
.space 0x400
- tramp_ventry
- tramp_ventry
- tramp_ventry
- tramp_ventry
+ .rept 4
+ tramp_ventry .Lvector_start\@, 64, \kpti, \bhb
+ .endr
+ .rept 4
+ tramp_ventry .Lvector_start\@, 32, \kpti, \bhb
+ .endr
+ .endm
- tramp_ventry 32
- tramp_ventry 32
- tramp_ventry 32
- tramp_ventry 32
+#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
+/*
+ * Exception vectors trampoline.
+ * The order must match __bp_harden_el1_vectors and the
+ * arm64_bp_harden_el1_vectors enum.
+ */
+ .pushsection ".entry.tramp.text", "ax"
+ .align 11
+SYM_CODE_START_NOALIGN(tramp_vectors)
+#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
+ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_LOOP
+ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_FW
+ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_INSN
+#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
+ generate_tramp_vector kpti=1, bhb=BHB_MITIGATION_NONE
SYM_CODE_END(tramp_vectors)
SYM_CODE_START(tramp_exit_native)
@@ -701,13 +771,57 @@ SYM_CODE_END(tramp_exit_compat)
.pushsection ".rodata", "a"
.align PAGE_SHIFT
SYM_DATA_START(__entry_tramp_data_start)
+__entry_tramp_data_vectors:
.quad vectors
+#ifdef CONFIG_ARM_SDE_INTERFACE
+__entry_tramp_data___sdei_asm_handler:
+ .quad __sdei_asm_handler
+#endif /* CONFIG_ARM_SDE_INTERFACE */
+__entry_tramp_data_this_cpu_vector:
+ .quad this_cpu_vector
SYM_DATA_END(__entry_tramp_data_start)
.popsection // .rodata
#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/*
+ * Exception vectors for spectre mitigations on entry from EL1 when
+ * kpti is not in use.
+ */
+ .macro generate_el1_vector, bhb
+.Lvector_start\@:
+ kernel_ventry 1, t, 64, sync // Synchronous EL1t
+ kernel_ventry 1, t, 64, irq // IRQ EL1t
+ kernel_ventry 1, t, 64, fiq // FIQ EL1h
+ kernel_ventry 1, t, 64, error // Error EL1t
+
+ kernel_ventry 1, h, 64, sync // Synchronous EL1h
+ kernel_ventry 1, h, 64, irq // IRQ EL1h
+ kernel_ventry 1, h, 64, fiq // FIQ EL1h
+ kernel_ventry 1, h, 64, error // Error EL1h
+
+ .rept 4
+ tramp_ventry .Lvector_start\@, 64, 0, \bhb
+ .endr
+ .rept 4
+ tramp_ventry .Lvector_start\@, 32, 0, \bhb
+ .endr
+ .endm
+
+/* The order must match tramp_vecs and the arm64_bp_harden_el1_vectors enum. */
+ .pushsection ".entry.text", "ax"
+ .align 11
+SYM_CODE_START(__bp_harden_el1_vectors)
+#ifdef CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY
+ generate_el1_vector bhb=BHB_MITIGATION_LOOP
+ generate_el1_vector bhb=BHB_MITIGATION_FW
+ generate_el1_vector bhb=BHB_MITIGATION_INSN
+#endif /* CONFIG_MITIGATE_SPECTRE_BRANCH_HISTORY */
+SYM_CODE_END(__bp_harden_el1_vectors)
+ .popsection
+
+
+/*
* Register switch for AArch64. The callee-saved registers need to be saved
* and restored. On entry:
* x0 = previous task_struct (must be preserved across the switch)
@@ -832,14 +946,7 @@ SYM_CODE_START(__sdei_asm_entry_trampoline)
* Remember whether to unmap the kernel on exit.
*/
1: str x4, [x1, #(SDEI_EVENT_INTREGS + S_SDEI_TTBR1)]
-
-#ifdef CONFIG_RANDOMIZE_BASE
- adr x4, tramp_vectors + PAGE_SIZE
- add x4, x4, #:lo12:__sdei_asm_trampoline_next_handler
- ldr x4, [x4]
-#else
- ldr x4, =__sdei_asm_handler
-#endif
+ tramp_data_read_var x4, __sdei_asm_handler
br x4
SYM_CODE_END(__sdei_asm_entry_trampoline)
NOKPROBE(__sdei_asm_entry_trampoline)
@@ -862,13 +969,6 @@ SYM_CODE_END(__sdei_asm_exit_trampoline)
NOKPROBE(__sdei_asm_exit_trampoline)
.ltorg
.popsection // .entry.tramp.text
-#ifdef CONFIG_RANDOMIZE_BASE
-.pushsection ".rodata", "a"
-SYM_DATA_START(__sdei_asm_trampoline_next_handler)
- .quad __sdei_asm_handler
-SYM_DATA_END(__sdei_asm_trampoline_next_handler)
-.popsection // .rodata
-#endif /* CONFIG_RANDOMIZE_BASE */
#endif /* CONFIG_UNMAP_KERNEL_AT_EL0 */
/*
@@ -978,7 +1078,7 @@ alternative_if_not ARM64_UNMAP_KERNEL_AT_EL0
alternative_else_nop_endif
#ifdef CONFIG_UNMAP_KERNEL_AT_EL0
- tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline
+ tramp_alias dst=x5, sym=__sdei_asm_exit_trampoline, tmp=x3
br x5
#endif
SYM_CODE_END(__sdei_asm_handler)