Using asm goto in __WARN_FLAGS() and WARN_ON() allows more
flexibility to GCC.
For that add an entry to the exception table so that
program_check_exception() knowns where to resume execution
after a WARNING.
Here are two exemples. The first one is done on PPC32 (which
benefits from the previous patch), the second is on PPC64.
unsigned long test(struct pt_regs *regs)
{
int ret;
WARN_ON(regs->msr & MSR_PR);
return regs->gpr[3];
}
unsigned long test9w(unsigned long a, unsigned long b)
{
if (WARN_ON(!b))
return 0;
return a / b;
}
Before the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
3c0: 80 63 00 0c lwz r3,12(r3)
3c4: 4e 80 00 20 blr
0000000000000bf0 <.test9w>:
bf0: 7c 89 00 74 cntlzd r9,r4
bf4: 79 29 d1 82 rldicl r9,r9,58,6
bf8: 0b 09 00 00 tdnei r9,0
bfc: 2c 24 00 00 cmpdi r4,0
c00: 41 82 00 0c beq c0c <.test9w+0x1c>
c04: 7c 63 23 92 divdu r3,r3,r4
c08: 4e 80 00 20 blr
c0c: 38 60 00 00 li r3,0
c10: 4e 80 00 20 blr
After the patch:
000003a8 <test>:
3a8: 81 23 00 84 lwz r9,132(r3)
3ac: 71 29 40 00 andi. r9,r9,16384
3b0: 40 82 00 0c bne 3bc <test+0x14>
3b4: 80 63 00 0c lwz r3,12(r3)
3b8: 4e 80 00 20 blr
3bc: 0f e0 00 00 twui r0,0
0000000000000c50 <.test9w>:
c50: 7c 89 00 74 cntlzd r9,r4
c54: 79 29 d1 82 rldicl r9,r9,58,6
c58: 0b 09 00 00 tdnei r9,0
c5c: 7c 63 23 92 divdu r3,r3,r4
c60: 4e 80 00 20 blr
c70: 38 60 00 00 li r3,0
c74: 4e 80 00 20 blr
In the first exemple, we see GCC doesn't need to duplicate what
happens after the trap.
In the second exemple, we see that GCC doesn't need to emit a test
and a branch in the likely path in addition to the trap.
We've got some WARN_ON() in .softirqentry.text section so it needs
to be added in the OTHER_TEXT_SECTIONS in modpost.c
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/389962b1b702e3c78d169e59bcfac56282889173.1618331882.git.christophe.leroy@csgroup.eu
/* Prevent access to userspace using any key values */
LOAD_REG_IMMEDIATE(\gpr2, AMR_KUAP_BLOCKED)
999: tdne \gpr1, \gpr2
- EMIT_BUG_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE)
+ EMIT_WARN_ENTRY 999b, __FILE__, __LINE__, (BUGFLAG_WARNING | BUGFLAG_ONCE)
END_MMU_FTR_SECTION_NESTED_IFSET(MMU_FTR_BOOK3S_KUAP, 67)
#endif
.endm
#ifdef __KERNEL__
#include <asm/asm-compat.h>
+#include <asm/extable.h>
#ifdef CONFIG_BUG
.endm
#endif /* verbose */
+.macro EMIT_WARN_ENTRY addr,file,line,flags
+ EX_TABLE(\addr,\addr+4)
+ EMIT_BUG_ENTRY \addr,\file,\line,\flags
+.endm
+
#else /* !__ASSEMBLY__ */
/* _EMIT_BUG_ENTRY expects args %0,%1,%2,%3 to be FILE, LINE, flags and
sizeof(struct bug_entry), respectively */
"i" (sizeof(struct bug_entry)), \
##__VA_ARGS__)
+#define WARN_ENTRY(insn, flags, label, ...) \
+ asm_volatile_goto( \
+ "1: " insn "\n" \
+ EX_TABLE(1b, %l[label]) \
+ _EMIT_BUG_ENTRY \
+ : : "i" (__FILE__), "i" (__LINE__), \
+ "i" (flags), \
+ "i" (sizeof(struct bug_entry)), \
+ ##__VA_ARGS__ : : label)
+
/*
* BUG_ON() and WARN_ON() do their best to cooperate with compile-time
* optimisations. However depending on the complexity of the condition
} while (0)
#define HAVE_ARCH_BUG
-#define __WARN_FLAGS(flags) BUG_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags))
+#define __WARN_FLAGS(flags) do { \
+ __label__ __label_warn_on; \
+ \
+ WARN_ENTRY("twi 31, 0, 0", BUGFLAG_WARNING | (flags), __label_warn_on); \
+ unreachable(); \
+ \
+__label_warn_on: \
+ break; \
+} while (0)
#ifdef CONFIG_PPC64
#define BUG_ON(x) do { \
} while (0)
#define WARN_ON(x) ({ \
- int __ret_warn_on = !!(x); \
- if (__builtin_constant_p(__ret_warn_on)) { \
- if (__ret_warn_on) \
+ bool __ret_warn_on = false; \
+ do { \
+ if (__builtin_constant_p((x))) { \
+ if (!(x)) \
+ break; \
__WARN(); \
- } else { \
- BUG_ENTRY(PPC_TLNEI " %4, 0", \
- BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN), \
- "r" (__ret_warn_on)); \
- } \
+ __ret_warn_on = true; \
+ } else { \
+ __label__ __label_warn_on; \
+ \
+ WARN_ENTRY(PPC_TLNEI " %4, 0", \
+ BUGFLAG_WARNING | BUGFLAG_TAINT(TAINT_WARN), \
+ __label_warn_on, "r" (x)); \
+ break; \
+__label_warn_on: \
+ __ret_warn_on = true; \
+ } \
+ } while (0); \
unlikely(__ret_warn_on); \
})
#ifdef __ASSEMBLY__
.macro EMIT_BUG_ENTRY addr,file,line,flags
.endm
+.macro EMIT_WARN_ENTRY addr,file,line,flags
+.endm
#else /* !__ASSEMBLY__ */
#define _EMIT_BUG_ENTRY
+#define _EMIT_WARN_ENTRY
#endif
#endif /* CONFIG_BUG */
#define ARCH_HAS_RELATIVE_EXTABLE
+#ifndef __ASSEMBLY__
+
struct exception_table_entry {
int insn;
int fixup;
}
#endif
+
+/*
+ * Helper macro for exception table entries
+ */
+#define EX_TABLE(_fault, _target) \
+ stringify_in_c(.section __ex_table,"a";)\
+ stringify_in_c(.balign 4;) \
+ stringify_in_c(.long (_fault) - . ;) \
+ stringify_in_c(.long (_target) - . ;) \
+ stringify_in_c(.previous)
+
+#endif
#include <asm/ppc-opcode.h>
#include <asm/firmware.h>
#include <asm/feature-fixups.h>
+#include <asm/extable.h>
#ifdef __ASSEMBLY__
#endif /* __ASSEMBLY__ */
-/*
- * Helper macro for exception table entries
- */
-#define EX_TABLE(_fault, _target) \
- stringify_in_c(.section __ex_table,"a";)\
- stringify_in_c(.balign 4;) \
- stringify_in_c(.long (_fault) - . ;) \
- stringify_in_c(.long (_target) - . ;) \
- stringify_in_c(.previous)
-
#define SOFT_MASK_TABLE(_start, _end) \
stringify_in_c(.section __soft_mask_table,"a";)\
stringify_in_c(.balign 8;) \
*/
lbz r0,PACAIRQSOFTMASK(r13)
1: tdeqi r0,IRQS_ENABLED
- EMIT_BUG_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
+ EMIT_WARN_ENTRY 1b,__FILE__,__LINE__,BUGFLAG_WARNING
#endif
/* Hard-disable interrupts */
addi r3,r3,-4
0: twnei r5, 0 /* WARN if r3 is not cache aligned */
- EMIT_BUG_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
+ EMIT_WARN_ENTRY 0b,__FILE__,__LINE__, BUGFLAG_WARNING
addi r4,r4,-4
if (!(regs->msr & MSR_PR) && /* not user-mode */
report_bug(bugaddr, regs) == BUG_TRAP_TYPE_WARN) {
- regs_add_return_ip(regs, 4);
- return;
+ const struct exception_table_entry *entry;
+
+ entry = search_exception_tables(bugaddr);
+ if (entry) {
+ regs_set_return_ip(regs, extable_fixup(entry) + regs->nip - bugaddr);
+ return;
+ }
}
_exception(SIGTRAP, regs, TRAP_BRKPT, regs->nip);
return;
".kprobes.text", ".cpuidle.text", ".noinstr.text"
#define OTHER_TEXT_SECTIONS ".ref.text", ".head.text", ".spinlock.text", \
".fixup", ".entry.text", ".exception.text", ".text.*", \
- ".coldtext"
+ ".coldtext", ".softirqentry.text"
#define INIT_SECTIONS ".init.*"
#define MEM_INIT_SECTIONS ".meminit.*"
--- /dev/null
+../../../../../../arch/powerpc/include/asm/extable.h
\ No newline at end of file
projects / kernel.git / commitdiff