Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
Merge tag 'riscv-for-linus-6.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V fixes from Palmer Dabbelt:
- RISC-V architecture-specific ELF attributes have been disabled in the
kernel builds
- A fix for a locking failure while during errata patching that
manifests on SiFive-based systems
- A fix for a KASAN failure during stack unwinding
- A fix for some lockdep failures during text patching
* tag 'riscv-for-linus-6.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux:
RISC-V: Don't check text_mutex during stop_machine
riscv: Use READ_ONCE_NOCHECK in imprecise unwinding stack mode
RISC-V: fix taking the text_mutex twice during sifive errata patching
RISC-V: Stop emitting attributes
+52
-8
+7
arch/riscv/Makefile
+7
arch/riscv/Makefile
···
84
84
# Avoid generating .eh_frame sections.
85
85
KBUILD_CFLAGS += -fno-asynchronous-unwind-tables -fno-unwind-tables
86
86
87
+
# The RISC-V attributes frequently cause compatibility issues and provide no
88
+
# information, so just turn them off.
89
+
KBUILD_CFLAGS += $(call cc-option,-mno-riscv-attribute)
90
+
KBUILD_AFLAGS += $(call cc-option,-mno-riscv-attribute)
91
+
KBUILD_CFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
92
+
KBUILD_AFLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
93
+
87
94
KBUILD_CFLAGS_MODULE += $(call cc-option,-mno-relax)
88
95
KBUILD_AFLAGS_MODULE += $(call as-option,-Wa$(comma)-mno-relax)
89
96
+1
-1
arch/riscv/errata/sifive/errata.c
+1
-1
arch/riscv/errata/sifive/errata.c
+1
-1
arch/riscv/include/asm/ftrace.h
+1
-1
arch/riscv/include/asm/ftrace.h
+2
arch/riscv/include/asm/patch.h
+2
arch/riscv/include/asm/patch.h
+4
arch/riscv/kernel/compat_vdso/Makefile
+4
arch/riscv/kernel/compat_vdso/Makefile
···
14
14
COMPAT_CC_FLAGS := -march=rv32g -mabi=ilp32
15
15
COMPAT_LD_FLAGS := -melf32lriscv
16
16
17
+
# Disable attributes, as they're useless and break the build.
18
+
COMPAT_CC_FLAGS += $(call cc-option,-mno-riscv-attribute)
19
+
COMPAT_CC_FLAGS += $(call as-option,-Wa$(comma)-mno-arch-attr)
20
+
17
21
# Files to link into the compat_vdso
18
22
obj-compat_vdso = $(patsubst %, %.o, $(compat_vdso-syms)) note.o
19
23
+11
-2
arch/riscv/kernel/ftrace.c
+11
-2
arch/riscv/kernel/ftrace.c
···
15
15
void ftrace_arch_code_modify_prepare(void) __acquires(&text_mutex)
16
16
{
17
17
mutex_lock(&text_mutex);
18
+
19
+
/*
20
+
* The code sequences we use for ftrace can't be patched while the
21
+
* kernel is running, so we need to use stop_machine() to modify them
22
+
* for now. This doesn't play nice with text_mutex, we use this flag
23
+
* to elide the check.
24
+
*/
25
+
riscv_patch_in_stop_machine = true;
18
26
}
19
27
20
28
void ftrace_arch_code_modify_post_process(void) __releases(&text_mutex)
21
29
{
30
+
riscv_patch_in_stop_machine = false;
22
31
mutex_unlock(&text_mutex);
23
32
}
24
33
···
116
107
{
117
108
int out;
118
109
119
-
ftrace_arch_code_modify_prepare();
110
+
mutex_lock(&text_mutex);
120
111
out = ftrace_make_nop(mod, rec, MCOUNT_ADDR);
121
-
ftrace_arch_code_modify_post_process();
112
+
mutex_unlock(&text_mutex);
122
113
123
114
return out;
124
115
}
+25
-3
arch/riscv/kernel/patch.c
+25
-3
arch/riscv/kernel/patch.c
···
11
11
#include <asm/kprobes.h>
12
12
#include <asm/cacheflush.h>
13
13
#include <asm/fixmap.h>
14
+
#include <asm/ftrace.h>
14
15
#include <asm/patch.h>
15
16
16
17
struct patch_insn {
···
20
19
int ninsns;
21
20
atomic_t cpu_count;
22
21
};
22
+
23
+
int riscv_patch_in_stop_machine = false;
23
24
24
25
#ifdef CONFIG_MMU
25
26
/*
···
63
60
* Before reaching here, it was expected to lock the text_mutex
64
61
* already, so we don't need to give another lock here and could
65
62
* ensure that it was safe between each cores.
63
+
*
64
+
* We're currently using stop_machine() for ftrace & kprobes, and while
65
+
* that ensures text_mutex is held before installing the mappings it
66
+
* does not ensure text_mutex is held by the calling thread. That's
67
+
* safe but triggers a lockdep failure, so just elide it for that
68
+
* specific case.
66
69
*/
67
-
lockdep_assert_held(&text_mutex);
70
+
if (!riscv_patch_in_stop_machine)
71
+
lockdep_assert_held(&text_mutex);
68
72
69
73
if (across_pages)
70
74
patch_map(addr + len, FIX_TEXT_POKE1);
···
135
125
136
126
int patch_text(void *addr, u32 *insns, int ninsns)
137
127
{
128
+
int ret;
138
129
struct patch_insn patch = {
139
130
.addr = addr,
140
131
.insns = insns,
···
143
132
.cpu_count = ATOMIC_INIT(0),
144
133
};
145
134
146
-
return stop_machine_cpuslocked(patch_text_cb,
147
-
&patch, cpu_online_mask);
135
+
/*
136
+
* kprobes takes text_mutex, before calling patch_text(), but as we call
137
+
* calls stop_machine(), the lockdep assertion in patch_insn_write()
138
+
* gets confused by the context in which the lock is taken.
139
+
* Instead, ensure the lock is held before calling stop_machine(), and
140
+
* set riscv_patch_in_stop_machine to skip the check in
141
+
* patch_insn_write().
142
+
*/
143
+
lockdep_assert_held(&text_mutex);
144
+
riscv_patch_in_stop_machine = true;
145
+
ret = stop_machine_cpuslocked(patch_text_cb, &patch, cpu_online_mask);
146
+
riscv_patch_in_stop_machine = false;
147
+
return ret;
148
148
}
149
149
NOKPROBE_SYMBOL(patch_text);