mirror of
https://github.com/torvalds/linux
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2b2fe6052d
Use rseq_unqual_scalar_typeof() rather than typeof() in macros to remove
the volatile qualifier (if there is one in the input argument), thus
generating better assembly code in those scenarios.
Also add extra brackets around the "p" parameter in RSEQ_READ_ONCE(),
RSEQ_WRITE_ONCE(), and rseq_unqual_scalar_typeof() across architectures
to preserve expectations of operator priority. Here is an example that
shows how operator priority may be an issue with missing parentheses:
#define m(p) \
do { \
__typeof__(*p) v = 0; \
} while (0)
void fct(unsigned long long *p1)
{
m(p1 + 1); /* works */
m(1 + p1); /* broken */
}
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
164 lines
5.4 KiB
C
164 lines
5.4 KiB
C
/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
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/*
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* RSEQ_SIG uses the trap4 instruction. As Linux does not make use of the
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* access-register mode nor the linkage stack this instruction will always
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* cause a special-operation exception (the trap-enabled bit in the DUCT
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* is and will stay 0). The instruction pattern is
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* b2 ff 0f ff trap4 4095(%r0)
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*/
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#define RSEQ_SIG 0xB2FF0FFF
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#define rseq_smp_mb() __asm__ __volatile__ ("bcr 15,0" ::: "memory")
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#define rseq_smp_rmb() rseq_smp_mb()
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#define rseq_smp_wmb() rseq_smp_mb()
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#define rseq_smp_load_acquire(p) \
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__extension__ ({ \
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rseq_unqual_scalar_typeof(*(p)) ____p1 = RSEQ_READ_ONCE(*(p)); \
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rseq_barrier(); \
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____p1; \
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})
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#define rseq_smp_acquire__after_ctrl_dep() rseq_smp_rmb()
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#define rseq_smp_store_release(p, v) \
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do { \
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rseq_barrier(); \
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RSEQ_WRITE_ONCE(*(p), v); \
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} while (0)
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#ifdef __s390x__
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#define LONG_L "lg"
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#define LONG_S "stg"
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#define LONG_LT_R "ltgr"
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#define LONG_CMP "cg"
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#define LONG_CMP_R "cgr"
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#define LONG_ADDI "aghi"
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#define LONG_ADD_R "agr"
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#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, \
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start_ip, post_commit_offset, abort_ip) \
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".pushsection __rseq_cs, \"aw\"\n\t" \
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".balign 32\n\t" \
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__rseq_str(label) ":\n\t" \
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".long " __rseq_str(version) ", " __rseq_str(flags) "\n\t" \
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".quad " __rseq_str(start_ip) ", " __rseq_str(post_commit_offset) ", " __rseq_str(abort_ip) "\n\t" \
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".popsection\n\t" \
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".pushsection __rseq_cs_ptr_array, \"aw\"\n\t" \
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".quad " __rseq_str(label) "b\n\t" \
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".popsection\n\t"
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/*
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* Exit points of a rseq critical section consist of all instructions outside
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* of the critical section where a critical section can either branch to or
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* reach through the normal course of its execution. The abort IP and the
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* post-commit IP are already part of the __rseq_cs section and should not be
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* explicitly defined as additional exit points. Knowing all exit points is
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* useful to assist debuggers stepping over the critical section.
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*/
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#define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip) \
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".pushsection __rseq_exit_point_array, \"aw\"\n\t" \
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".quad " __rseq_str(start_ip) ", " __rseq_str(exit_ip) "\n\t" \
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".popsection\n\t"
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#elif __s390__
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#define __RSEQ_ASM_DEFINE_TABLE(label, version, flags, \
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start_ip, post_commit_offset, abort_ip) \
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".pushsection __rseq_cs, \"aw\"\n\t" \
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".balign 32\n\t" \
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__rseq_str(label) ":\n\t" \
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".long " __rseq_str(version) ", " __rseq_str(flags) "\n\t" \
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".long 0x0, " __rseq_str(start_ip) ", 0x0, " __rseq_str(post_commit_offset) ", 0x0, " __rseq_str(abort_ip) "\n\t" \
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".popsection\n\t" \
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".pushsection __rseq_cs_ptr_array, \"aw\"\n\t" \
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".long 0x0, " __rseq_str(label) "b\n\t" \
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".popsection\n\t"
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/*
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* Exit points of a rseq critical section consist of all instructions outside
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* of the critical section where a critical section can either branch to or
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* reach through the normal course of its execution. The abort IP and the
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* post-commit IP are already part of the __rseq_cs section and should not be
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* explicitly defined as additional exit points. Knowing all exit points is
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* useful to assist debuggers stepping over the critical section.
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*/
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#define RSEQ_ASM_DEFINE_EXIT_POINT(start_ip, exit_ip) \
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".pushsection __rseq_exit_point_array, \"aw\"\n\t" \
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".long 0x0, " __rseq_str(start_ip) ", 0x0, " __rseq_str(exit_ip) "\n\t" \
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".popsection\n\t"
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#define LONG_L "l"
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#define LONG_S "st"
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#define LONG_LT_R "ltr"
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#define LONG_CMP "c"
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#define LONG_CMP_R "cr"
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#define LONG_ADDI "ahi"
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#define LONG_ADD_R "ar"
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#endif
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#define RSEQ_ASM_DEFINE_TABLE(label, start_ip, post_commit_ip, abort_ip) \
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__RSEQ_ASM_DEFINE_TABLE(label, 0x0, 0x0, start_ip, \
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(post_commit_ip - start_ip), abort_ip)
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#define RSEQ_ASM_STORE_RSEQ_CS(label, cs_label, rseq_cs) \
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RSEQ_INJECT_ASM(1) \
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"larl %%r0, " __rseq_str(cs_label) "\n\t" \
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LONG_S " %%r0, %[" __rseq_str(rseq_cs) "]\n\t" \
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__rseq_str(label) ":\n\t"
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#define RSEQ_ASM_CMP_CPU_ID(cpu_id, current_cpu_id, label) \
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RSEQ_INJECT_ASM(2) \
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"c %[" __rseq_str(cpu_id) "], %[" __rseq_str(current_cpu_id) "]\n\t" \
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"jnz " __rseq_str(label) "\n\t"
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#define RSEQ_ASM_DEFINE_ABORT(label, teardown, abort_label) \
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".pushsection __rseq_failure, \"ax\"\n\t" \
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".long " __rseq_str(RSEQ_SIG) "\n\t" \
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__rseq_str(label) ":\n\t" \
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teardown \
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"jg %l[" __rseq_str(abort_label) "]\n\t" \
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".popsection\n\t"
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#define RSEQ_ASM_DEFINE_CMPFAIL(label, teardown, cmpfail_label) \
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".pushsection __rseq_failure, \"ax\"\n\t" \
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__rseq_str(label) ":\n\t" \
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teardown \
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"jg %l[" __rseq_str(cmpfail_label) "]\n\t" \
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".popsection\n\t"
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/* Per-cpu-id indexing. */
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#define RSEQ_TEMPLATE_CPU_ID
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#define RSEQ_TEMPLATE_MO_RELAXED
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#include "rseq-s390-bits.h"
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#undef RSEQ_TEMPLATE_MO_RELAXED
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#define RSEQ_TEMPLATE_MO_RELEASE
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#include "rseq-s390-bits.h"
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#undef RSEQ_TEMPLATE_MO_RELEASE
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#undef RSEQ_TEMPLATE_CPU_ID
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/* Per-mm-cid indexing. */
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#define RSEQ_TEMPLATE_MM_CID
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#define RSEQ_TEMPLATE_MO_RELAXED
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#include "rseq-s390-bits.h"
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#undef RSEQ_TEMPLATE_MO_RELAXED
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#define RSEQ_TEMPLATE_MO_RELEASE
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#include "rseq-s390-bits.h"
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#undef RSEQ_TEMPLATE_MO_RELEASE
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#undef RSEQ_TEMPLATE_MM_CID
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/* APIs which are not based on cpu ids. */
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#define RSEQ_TEMPLATE_CPU_ID_NONE
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#define RSEQ_TEMPLATE_MO_RELAXED
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#include "rseq-s390-bits.h"
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#undef RSEQ_TEMPLATE_MO_RELAXED
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#undef RSEQ_TEMPLATE_CPU_ID_NONE
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