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| author | Youling Tang <tangyouling@loongson.cn> | 2022-10-12 16:36:19 +0800 |
|---|---|---|
| committer | Huacai Chen <chenhuacai@loongson.cn> | 2022-10-12 16:36:19 +0800 |
| commit | 2d2c395217d2233e752dbddcae3c5d94050b48c1 (patch) | |
| tree | b632f68aef7055a5dba5481123a3190e75bc98e5 /arch/loongarch/kernel | |
| parent | dea2df3cc72555633cc7858ce1daa4b757f843ad (diff) | |
| download | linux-2d2c395217d2233e752dbddcae3c5d94050b48c1.tar.bz2 | |
LoongArch: Use generic BUG() handler
Inspired by commit 9fb7410f955("arm64/BUG: Use BRK instruction for
generic BUG traps"), do similar for LoongArch to use generic BUG()
handler.
This patch uses the BREAK software breakpoint instruction to generate
a trap instead, similarly to most other arches, with the generic BUG
code generating the dmesg boilerplate.
This allows bug metadata to be moved to a separate table and reduces
the amount of inline code at BUG() and WARN() sites. This also avoids
clobbering any registers before they can be dumped.
To mitigate the size of the bug table further, this patch makes use of
the existing infrastructure for encoding addresses within the bug table
as 32-bit relative pointers instead of absolute pointers.
(Note: this limits the max kernel size to 2GB.)
Before patch:
[ 3018.338013] lkdtm: Performing direct entry BUG
[ 3018.342445] Kernel bug detected[#5]:
[ 3018.345992] CPU: 2 PID: 865 Comm: cat Tainted: G D 6.0.0-rc6+ #35
After patch:
[ 125.585985] lkdtm: Performing direct entry BUG
[ 125.590433] ------------[ cut here ]------------
[ 125.595020] kernel BUG at drivers/misc/lkdtm/bugs.c:78!
[ 125.600211] Oops - BUG[#1]:
[ 125.602980] CPU: 3 PID: 410 Comm: cat Not tainted 6.0.0-rc6+ #36
Out-of-line file/line data information obtained compared to before.
Signed-off-by: Youling Tang <tangyouling@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Diffstat (limited to 'arch/loongarch/kernel')
| -rw-r--r-- | arch/loongarch/kernel/head.S | 4 | ||||
| -rw-r--r-- | arch/loongarch/kernel/traps.c | 26 |
2 files changed, 28 insertions, 2 deletions
diff --git a/arch/loongarch/kernel/head.S b/arch/loongarch/kernel/head.S index 0c67c24ce087..d32128f1d3c4 100644 --- a/arch/loongarch/kernel/head.S +++ b/arch/loongarch/kernel/head.S @@ -8,6 +8,7 @@ #include <asm/addrspace.h> #include <asm/asm.h> #include <asm/asmmacro.h> +#include <asm/bug.h> #include <asm/regdef.h> #include <asm/loongarch.h> #include <asm/stackframe.h> @@ -85,6 +86,7 @@ SYM_CODE_START(kernel_entry) # kernel entry point PTR_ADDI sp, sp, -4 * SZREG # init stack pointer bl start_kernel + ASM_BUG() SYM_CODE_END(kernel_entry) @@ -116,6 +118,8 @@ SYM_CODE_START(smpboot_entry) ld.d tp, t0, CPU_BOOT_TINFO bl start_secondary + ASM_BUG() + SYM_CODE_END(smpboot_entry) #endif /* CONFIG_SMP */ diff --git a/arch/loongarch/kernel/traps.c b/arch/loongarch/kernel/traps.c index a5e8bd5d7948..66c2849b26e5 100644 --- a/arch/loongarch/kernel/traps.c +++ b/arch/loongarch/kernel/traps.c @@ -374,6 +374,29 @@ asmlinkage void noinstr do_ale(struct pt_regs *regs) irqentry_exit(regs, state); } +#ifdef CONFIG_GENERIC_BUG +int is_valid_bugaddr(unsigned long addr) +{ + return 1; +} +#endif /* CONFIG_GENERIC_BUG */ + +static void bug_handler(struct pt_regs *regs) +{ + switch (report_bug(regs->csr_era, regs)) { + case BUG_TRAP_TYPE_BUG: + case BUG_TRAP_TYPE_NONE: + die_if_kernel("Oops - BUG", regs); + force_sig(SIGTRAP); + break; + + case BUG_TRAP_TYPE_WARN: + /* Skip the BUG instruction and continue */ + regs->csr_era += LOONGARCH_INSN_SIZE; + break; + } +} + asmlinkage void noinstr do_bp(struct pt_regs *regs) { bool user = user_mode(regs); @@ -427,8 +450,7 @@ asmlinkage void noinstr do_bp(struct pt_regs *regs) switch (bcode) { case BRK_BUG: - die_if_kernel("Kernel bug detected", regs); - force_sig(SIGTRAP); + bug_handler(regs); break; case BRK_DIVZERO: die_if_kernel("Break instruction in kernel code", regs); |