This is a note to let you know that I've just added the patch titled
RISC-V: take text_mutex during alternative patching
to the 6.2-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
risc-v-take-text_mutex-during-alternative-patching.patch
and it can be found in the queue-6.2 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit cdb68604f94eb8323964cc8cece2b292d520c1fe
Author: Sasha Levin <sashal@xxxxxxxxxx>
Date: Mon Mar 13 11:43:48 2023 -0400
RISC-V: take text_mutex during alternative patching
[ Upstream commit 9493e6f3ce02f44c21aa19f3cbf3b9aa05479d06 ]
Guenter reported a splat during boot, that Samuel pointed out was the
lockdep assertion failing in patch_insn_write():
WARNING: CPU: 0 PID: 0 at arch/riscv/kernel/patch.c:63 patch_insn_write+0x222/0x2f6
epc : patch_insn_write+0x222/0x2f6
ra : patch_insn_write+0x21e/0x2f6
epc : ffffffff800068c6 ra : ffffffff800068c2 sp : ffffffff81803df0
gp : ffffffff81a1ab78 tp : ffffffff81814f80 t0 : ffffffffffffe000
t1 : 0000000000000001 t2 : 4c45203a76637369 s0 : ffffffff81803e40
s1 : 0000000000000004 a0 : 0000000000000000 a1 : ffffffffffffffff
a2 : 0000000000000004 a3 : 0000000000000000 a4 : 0000000000000001
a5 : 0000000000000000 a6 : 0000000000000000 a7 : 0000000052464e43
s2 : ffffffff80b4889c s3 : 000000000000082c s4 : ffffffff80b48828
s5 : 0000000000000828 s6 : ffffffff8131a0a0 s7 : 0000000000000fff
s8 : 0000000008000200 s9 : ffffffff8131a520 s10: 0000000000000018
s11: 000000000000000b t3 : 0000000000000001 t4 : 000000000000000d
t5 : ffffffffd8180000 t6 : ffffffff81803bc8
status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000003
[<ffffffff800068c6>] patch_insn_write+0x222/0x2f6
[<ffffffff80006a36>] patch_text_nosync+0xc/0x2a
[<ffffffff80003b86>] riscv_cpufeature_patch_func+0x52/0x98
[<ffffffff80003348>] _apply_alternatives+0x46/0x86
[<ffffffff80c02d36>] apply_boot_alternatives+0x3c/0xfa
[<ffffffff80c03ad8>] setup_arch+0x584/0x5b8
[<ffffffff80c0075a>] start_kernel+0xa2/0x8f8
This issue was exposed by 702e64550b12 ("riscv: fpu: switch has_fpu() to
riscv_has_extension_likely()"), as it is the patching in has_fpu() that
triggers the splats in Guenter's report.
Take the text_mutex before doing any code patching to satisfy lockdep.
Fixes: ff689fd21cb1 ("riscv: add RISC-V Svpbmt extension support")
Fixes: a35707c3d850 ("riscv: add memory-type errata for T-Head")
Fixes: 1a0e5dbd3723 ("riscv: sifive: Add SiFive alternative ports")
Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Link: https://lore.kernel.org/all/20230212154333.GA3760469@xxxxxxxxxxxx/
Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
Reviewed-by: Samuel Holland <samuel@xxxxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230212194735.491785-1-conor@xxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/riscv/errata/sifive/errata.c b/arch/riscv/errata/sifive/errata.c
index 1031038423e74..5b77d7310e391 100644
--- a/arch/riscv/errata/sifive/errata.c
+++ b/arch/riscv/errata/sifive/errata.c
@@ -4,6 +4,7 @@
*/
#include <linux/kernel.h>
+#include <linux/memory.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/bug.h>
@@ -107,7 +108,9 @@ void __init_or_module sifive_errata_patch_func(struct alt_entry *begin,
tmp = (1U << alt->errata_id);
if (cpu_req_errata & tmp) {
+ mutex_lock(&text_mutex);
patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ mutex_lock(&text_mutex);
cpu_apply_errata |= tmp;
}
}
diff --git a/arch/riscv/errata/thead/errata.c b/arch/riscv/errata/thead/errata.c
index fac5742d1c1e6..9d71fe3d35c77 100644
--- a/arch/riscv/errata/thead/errata.c
+++ b/arch/riscv/errata/thead/errata.c
@@ -5,6 +5,7 @@
#include <linux/bug.h>
#include <linux/kernel.h>
+#include <linux/memory.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/uaccess.h>
@@ -97,11 +98,14 @@ void __init_or_module thead_errata_patch_func(struct alt_entry *begin, struct al
tmp = (1U << alt->errata_id);
if (cpu_req_errata & tmp) {
/* On vm-alternatives, the mmu isn't running yet */
- if (stage == RISCV_ALTERNATIVES_EARLY_BOOT)
+ if (stage == RISCV_ALTERNATIVES_EARLY_BOOT) {
memcpy((void *)__pa_symbol(alt->old_ptr),
(void *)__pa_symbol(alt->alt_ptr), alt->alt_len);
- else
+ } else {
+ mutex_lock(&text_mutex);
patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ mutex_unlock(&text_mutex);
+ }
}
}
diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c
index 93e45560af307..5a82d5520a1fd 100644
--- a/arch/riscv/kernel/cpufeature.c
+++ b/arch/riscv/kernel/cpufeature.c
@@ -10,6 +10,7 @@
#include <linux/ctype.h>
#include <linux/libfdt.h>
#include <linux/log2.h>
+#include <linux/memory.h>
#include <linux/module.h>
#include <linux/of.h>
#include <asm/alternative.h>
@@ -339,8 +340,11 @@ void __init_or_module riscv_cpufeature_patch_func(struct alt_entry *begin,
}
tmp = (1U << alt->errata_id);
- if (cpu_req_feature & tmp)
+ if (cpu_req_feature & tmp) {
+ mutex_lock(&text_mutex);
patch_text_nosync(alt->old_ptr, alt->alt_ptr, alt->alt_len);
+ mutex_unlock(&text_mutex);
+ }
}
}
#endif
