aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorRussell King <rmk+kernel@armlinux.org.uk>2018-05-11 11:16:22 +0100
committerDavid A. Long <dave.long@linaro.org>2018-10-30 23:23:46 -0400
commitf79b41c803919dcb44a18c4e29ab551b1f8d2d00 (patch)
treebba4c173836be9ac4f847b86f22fc64214f732b1
parent5a6278c73c27599e79f65602e83fd7cb5cef9fd4 (diff)
downloadlinux-linaro-stable-f79b41c803919dcb44a18c4e29ab551b1f8d2d00.tar.gz
ARM: spectre-v1: fix syscall entry
Commit 10573ae547c85b2c61417ff1a106cffbfceada35 upstream. Prevent speculation at the syscall table decoding by clamping the index used to zero on invalid system call numbers, and using the csdb speculative barrier. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk> Acked-by: Mark Rutland <mark.rutland@arm.com> Boot-tested-by: Tony Lindgren <tony@atomide.com> Reviewed-by: Tony Lindgren <tony@atomide.com> Signed-off-by: David A. Long <dave.long@linaro.org>
-rw-r--r--arch/arm/kernel/entry-common.S18
-rw-r--r--arch/arm/kernel/entry-header.S25
2 files changed, 32 insertions, 11 deletions
diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
index 30a7228eaceb..e969b18d9ff9 100644
--- a/arch/arm/kernel/entry-common.S
+++ b/arch/arm/kernel/entry-common.S
@@ -223,9 +223,7 @@ local_restart:
tst r10, #_TIF_SYSCALL_WORK @ are we tracing syscalls?
bne __sys_trace
- cmp scno, #NR_syscalls @ check upper syscall limit
- badr lr, ret_fast_syscall @ return address
- ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
+ invoke_syscall tbl, scno, r10, ret_fast_syscall
add r1, sp, #S_OFF
2: cmp scno, #(__ARM_NR_BASE - __NR_SYSCALL_BASE)
@@ -258,14 +256,8 @@ __sys_trace:
mov r1, scno
add r0, sp, #S_OFF
bl syscall_trace_enter
-
- badr lr, __sys_trace_return @ return address
- mov scno, r0 @ syscall number (possibly new)
- add r1, sp, #S_R0 + S_OFF @ pointer to regs
- cmp scno, #NR_syscalls @ check upper syscall limit
- ldmccia r1, {r0 - r6} @ have to reload r0 - r6
- stmccia sp, {r4, r5} @ and update the stack args
- ldrcc pc, [tbl, scno, lsl #2] @ call sys_* routine
+ mov scno, r0
+ invoke_syscall tbl, scno, r10, __sys_trace_return, reload=1
cmp scno, #-1 @ skip the syscall?
bne 2b
add sp, sp, #S_OFF @ restore stack
@@ -317,6 +309,10 @@ sys_syscall:
bic scno, r0, #__NR_OABI_SYSCALL_BASE
cmp scno, #__NR_syscall - __NR_SYSCALL_BASE
cmpne scno, #NR_syscalls @ check range
+#ifdef CONFIG_CPU_SPECTRE
+ movhs scno, #0
+ csdb
+#endif
stmloia sp, {r5, r6} @ shuffle args
movlo r0, r1
movlo r1, r2
diff --git a/arch/arm/kernel/entry-header.S b/arch/arm/kernel/entry-header.S
index 6d243e830516..86dfee487e24 100644
--- a/arch/arm/kernel/entry-header.S
+++ b/arch/arm/kernel/entry-header.S
@@ -373,6 +373,31 @@
#endif
.endm
+ .macro invoke_syscall, table, nr, tmp, ret, reload=0
+#ifdef CONFIG_CPU_SPECTRE
+ mov \tmp, \nr
+ cmp \tmp, #NR_syscalls @ check upper syscall limit
+ movcs \tmp, #0
+ csdb
+ badr lr, \ret @ return address
+ .if \reload
+ add r1, sp, #S_R0 + S_OFF @ pointer to regs
+ ldmccia r1, {r0 - r6} @ reload r0-r6
+ stmccia sp, {r4, r5} @ update stack arguments
+ .endif
+ ldrcc pc, [\table, \tmp, lsl #2] @ call sys_* routine
+#else
+ cmp \nr, #NR_syscalls @ check upper syscall limit
+ badr lr, \ret @ return address
+ .if \reload
+ add r1, sp, #S_R0 + S_OFF @ pointer to regs
+ ldmccia r1, {r0 - r6} @ reload r0-r6
+ stmccia sp, {r4, r5} @ update stack arguments
+ .endif
+ ldrcc pc, [\table, \nr, lsl #2] @ call sys_* routine
+#endif
+ .endm
+
/*
* These are the registers used in the syscall handler, and allow us to
* have in theory up to 7 arguments to a function - r0 to r6.