* [PATCH 5.3 082/166] MIPS: Ingenic: Disable broken BTB lookup optimization.
[not found] <20191006171212.850660298@linuxfoundation.org>
@ 2019-10-06 17:20 ` Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 083/166] MIPS: Dont use bc_false uninitialized in __mm_isBranchInstr Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 084/166] MIPS: tlbex: Explicitly cast _PAGE_NO_EXEC to a boolean Greg Kroah-Hartman
2 siblings, 0 replies; 3+ messages in thread
From: Greg Kroah-Hartman @ 2019-10-06 17:20 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Zhou Yanjie, Paul Burton, linux-mips,
ralf, paul, jhogan, malat, tglx, allison, syq, chenhc,
jiaxun.yang, Sasha Levin
From: Zhou Yanjie <zhouyanjie@zoho.com>
[ Upstream commit 053951dda71ecb4b554a2cdbe26f5f6f9bee9dd2 ]
In order to further reduce power consumption, the XBurst core
by default attempts to avoid branch target buffer lookups by
detecting & special casing loops. This feature will cause
BogoMIPS and lpj calculate in error. Set cp0 config7 bit 4 to
disable this feature.
Signed-off-by: Zhou Yanjie <zhouyanjie@zoho.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: ralf@linux-mips.org
Cc: paul@crapouillou.net
Cc: jhogan@kernel.org
Cc: malat@debian.org
Cc: gregkh@linuxfoundation.org
Cc: tglx@linutronix.de
Cc: allison@lohutok.net
Cc: syq@debian.org
Cc: chenhc@lemote.com
Cc: jiaxun.yang@flygoat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/include/asm/mipsregs.h | 4 ++++
arch/mips/kernel/cpu-probe.c | 7 +++++++
2 files changed, 11 insertions(+)
diff --git a/arch/mips/include/asm/mipsregs.h b/arch/mips/include/asm/mipsregs.h
index 1e6966e8527e9..bdbdc19a2b8f8 100644
--- a/arch/mips/include/asm/mipsregs.h
+++ b/arch/mips/include/asm/mipsregs.h
@@ -689,6 +689,9 @@
#define MIPS_CONF7_IAR (_ULCAST_(1) << 10)
#define MIPS_CONF7_AR (_ULCAST_(1) << 16)
+/* Ingenic Config7 bits */
+#define MIPS_CONF7_BTB_LOOP_EN (_ULCAST_(1) << 4)
+
/* Config7 Bits specific to MIPS Technologies. */
/* Performance counters implemented Per TC */
@@ -2813,6 +2816,7 @@ __BUILD_SET_C0(status)
__BUILD_SET_C0(cause)
__BUILD_SET_C0(config)
__BUILD_SET_C0(config5)
+__BUILD_SET_C0(config7)
__BUILD_SET_C0(intcontrol)
__BUILD_SET_C0(intctl)
__BUILD_SET_C0(srsmap)
diff --git a/arch/mips/kernel/cpu-probe.c b/arch/mips/kernel/cpu-probe.c
index 9635c1db3ae6a..e654ffc1c8a0d 100644
--- a/arch/mips/kernel/cpu-probe.c
+++ b/arch/mips/kernel/cpu-probe.c
@@ -1964,6 +1964,13 @@ static inline void cpu_probe_ingenic(struct cpuinfo_mips *c, unsigned int cpu)
c->cputype = CPU_JZRISC;
c->writecombine = _CACHE_UNCACHED_ACCELERATED;
__cpu_name[cpu] = "Ingenic JZRISC";
+ /*
+ * The XBurst core by default attempts to avoid branch target
+ * buffer lookups by detecting & special casing loops. This
+ * feature will cause BogoMIPS and lpj calculate in error.
+ * Set cp0 config7 bit 4 to disable this feature.
+ */
+ set_c0_config7(MIPS_CONF7_BTB_LOOP_EN);
break;
default:
panic("Unknown Ingenic Processor ID!");
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 5.3 083/166] MIPS: Dont use bc_false uninitialized in __mm_isBranchInstr
[not found] <20191006171212.850660298@linuxfoundation.org>
2019-10-06 17:20 ` [PATCH 5.3 082/166] MIPS: Ingenic: Disable broken BTB lookup optimization Greg Kroah-Hartman
@ 2019-10-06 17:20 ` Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 084/166] MIPS: tlbex: Explicitly cast _PAGE_NO_EXEC to a boolean Greg Kroah-Hartman
2 siblings, 0 replies; 3+ messages in thread
From: Greg Kroah-Hartman @ 2019-10-06 17:20 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Nathan Chancellor, Paul Burton,
Ralf Baechle, James Hogan, Nick Desaulniers, linux-mips,
clang-built-linux, Sasha Levin
From: Nathan Chancellor <natechancellor@gmail.com>
[ Upstream commit c2869aafe7191d366d74c55cb8a93c6d0baba317 ]
clang warns:
arch/mips/kernel/branch.c:148:8: error: variable 'bc_false' is used
uninitialized whenever switch case is taken
[-Werror,-Wsometimes-uninitialized]
case mm_bc2t_op:
^~~~~~~~~~
arch/mips/kernel/branch.c:157:8: note: uninitialized use occurs here
if (bc_false)
^~~~~~~~
arch/mips/kernel/branch.c:149:8: error: variable 'bc_false' is used
uninitialized whenever switch case is taken
[-Werror,-Wsometimes-uninitialized]
case mm_bc1t_op:
^~~~~~~~~~
arch/mips/kernel/branch.c:157:8: note: uninitialized use occurs here
if (bc_false)
^~~~~~~~
arch/mips/kernel/branch.c:142:4: note: variable 'bc_false' is declared
here
int bc_false = 0;
^
2 errors generated.
When mm_bc1t_op and mm_bc2t_op are taken, the bc_false initialization
does not happen, which leads to a garbage value upon use, as illustrated
below with a small sample program.
$ mipsel-linux-gnu-gcc --version | head -n1
mipsel-linux-gnu-gcc (Debian 8.3.0-2) 8.3.0
$ clang --version | head -n1
ClangBuiltLinux clang version 9.0.0 (git://github.com/llvm/llvm-project
544315b4197034a3be8acd12cba56a75fb1f08dc) (based on LLVM 9.0.0svn)
$ cat test.c
#include <stdio.h>
static void switch_scoped(int opcode)
{
switch (opcode) {
case 1:
case 2: {
int bc_false = 0;
bc_false = 4;
case 3:
case 4:
printf("\t* switch scoped bc_false = %d\n", bc_false);
}
}
}
static void function_scoped(int opcode)
{
int bc_false = 0;
switch (opcode) {
case 1:
case 2: {
bc_false = 4;
case 3:
case 4:
printf("\t* function scoped bc_false = %d\n", bc_false);
}
}
}
int main(void)
{
int opcode;
for (opcode = 1; opcode < 5; opcode++) {
printf("opcode = %d:\n", opcode);
switch_scoped(opcode);
function_scoped(opcode);
printf("\n");
}
return 0;
}
$ mipsel-linux-gnu-gcc -std=gnu89 -static test.c && \
qemu-mipsel a.out
opcode = 1:
* switch scoped bc_false = 4
* function scoped bc_false = 4
opcode = 2:
* switch scoped bc_false = 4
* function scoped bc_false = 4
opcode = 3:
* switch scoped bc_false = 2147483004
* function scoped bc_false = 0
opcode = 4:
* switch scoped bc_false = 2147483004
* function scoped bc_false = 0
$ clang -std=gnu89 --target=mipsel-linux-gnu -m32 -static test.c && \
qemu-mipsel a.out
opcode = 1:
* switch scoped bc_false = 4
* function scoped bc_false = 4
opcode = 2:
* switch scoped bc_false = 4
* function scoped bc_false = 4
opcode = 3:
* switch scoped bc_false = 2147483004
* function scoped bc_false = 0
opcode = 4:
* switch scoped bc_false = 2147483004
* function scoped bc_false = 0
Move the definition up so that we get the right behavior and mark it
__maybe_unused as it will not be used when CONFIG_MIPS_FP_SUPPORT
isn't enabled.
Fixes: 6a1cc218b9cc ("MIPS: branch: Remove FP branch handling when CONFIG_MIPS_FP_SUPPORT=n")
Link: https://github.com/ClangBuiltLinux/linux/issues/603
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/kernel/branch.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 1db29957a9318..2c38f75d87ffb 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -58,6 +58,7 @@ int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
unsigned long *contpc)
{
union mips_instruction insn = (union mips_instruction)dec_insn.insn;
+ int __maybe_unused bc_false = 0;
if (!cpu_has_mmips)
return 0;
@@ -139,7 +140,6 @@ int __mm_isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
#ifdef CONFIG_MIPS_FP_SUPPORT
case mm_bc2f_op:
case mm_bc1f_op: {
- int bc_false = 0;
unsigned int fcr31;
unsigned int bit;
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 5.3 084/166] MIPS: tlbex: Explicitly cast _PAGE_NO_EXEC to a boolean
[not found] <20191006171212.850660298@linuxfoundation.org>
2019-10-06 17:20 ` [PATCH 5.3 082/166] MIPS: Ingenic: Disable broken BTB lookup optimization Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 083/166] MIPS: Dont use bc_false uninitialized in __mm_isBranchInstr Greg Kroah-Hartman
@ 2019-10-06 17:20 ` Greg Kroah-Hartman
2 siblings, 0 replies; 3+ messages in thread
From: Greg Kroah-Hartman @ 2019-10-06 17:20 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Nathan Chancellor, Paul Burton,
Ralf Baechle, James Hogan, Nick Desaulniers, linux-mips,
clang-built-linux, Sasha Levin
From: Nathan Chancellor <natechancellor@gmail.com>
[ Upstream commit c59ae0a1055127dd3828a88e111a0db59b254104 ]
clang warns:
arch/mips/mm/tlbex.c:634:19: error: use of logical '&&' with constant
operand [-Werror,-Wconstant-logical-operand]
if (cpu_has_rixi && _PAGE_NO_EXEC) {
^ ~~~~~~~~~~~~~
arch/mips/mm/tlbex.c:634:19: note: use '&' for a bitwise operation
if (cpu_has_rixi && _PAGE_NO_EXEC) {
^~
&
arch/mips/mm/tlbex.c:634:19: note: remove constant to silence this
warning
if (cpu_has_rixi && _PAGE_NO_EXEC) {
~^~~~~~~~~~~~~~~~
1 error generated.
Explicitly cast this value to a boolean so that clang understands we
intend for this to be a non-zero value.
Fixes: 00bf1c691d08 ("MIPS: tlbex: Avoid placing software PTE bits in Entry* PFN fields")
Link: https://github.com/ClangBuiltLinux/linux/issues/609
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Paul Burton <paul.burton@mips.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: James Hogan <jhogan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: linux-mips@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: clang-built-linux@googlegroups.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/mips/mm/tlbex.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/mm/tlbex.c b/arch/mips/mm/tlbex.c
index 144ceb0fba88f..bece1264d1c5a 100644
--- a/arch/mips/mm/tlbex.c
+++ b/arch/mips/mm/tlbex.c
@@ -631,7 +631,7 @@ static __maybe_unused void build_convert_pte_to_entrylo(u32 **p,
return;
}
- if (cpu_has_rixi && _PAGE_NO_EXEC) {
+ if (cpu_has_rixi && !!_PAGE_NO_EXEC) {
if (fill_includes_sw_bits) {
UASM_i_ROTR(p, reg, reg, ilog2(_PAGE_GLOBAL));
} else {
--
2.20.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
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2019-10-06 17:20 ` [PATCH 5.3 082/166] MIPS: Ingenic: Disable broken BTB lookup optimization Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 083/166] MIPS: Dont use bc_false uninitialized in __mm_isBranchInstr Greg Kroah-Hartman
2019-10-06 17:20 ` [PATCH 5.3 084/166] MIPS: tlbex: Explicitly cast _PAGE_NO_EXEC to a boolean Greg Kroah-Hartman
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