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| author | Richard Henderson <richard.henderson@linaro.org> | 2021-11-15 14:08:52 +0100 |
|---|---|---|
| committer | Richard Henderson <richard.henderson@linaro.org> | 2021-12-19 20:47:33 -0800 |
| commit | a3310c0397e21df8f47cde3e55736104b9584d2d (patch) | |
| tree | 2e550417028aea39886ba22f4b60fb9c88404630 /linux-user/host/s390x | |
| parent | b9d2af3c62c22870c02410d5c9c6d097ee0ddf3f (diff) | |
| download | qemu-a3310c0397e21df8f47cde3e55736104b9584d2d.zip qemu-a3310c0397e21df8f47cde3e55736104b9584d2d.tar.gz qemu-a3310c0397e21df8f47cde3e55736104b9584d2d.tar.bz2 | |
linux-user: Move syscall error detection into safe_syscall_base
The current api from safe_syscall_base() is to return -errno, which is
the interface provided by *some* linux kernel abis. The wrapper macro,
safe_syscall(), detects error, stores into errno, and returns -1, to
match the api of the system syscall().
For those kernel abis that do not return -errno natively, this leads
to double syscall error detection. E.g. Linux ppc64, which sets the
SO flag for error.
Simplify the usage from C by moving the error detection into assembly,
and usage from assembly by providing a C helper with which to set errno.
Reviewed-by: Warner Losh <imp@bsdimp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Diffstat (limited to 'linux-user/host/s390x')
| -rw-r--r-- | linux-user/host/s390x/safe-syscall.inc.S | 30 |
1 files changed, 19 insertions, 11 deletions
diff --git a/linux-user/host/s390x/safe-syscall.inc.S b/linux-user/host/s390x/safe-syscall.inc.S index d97d274..899dab3 100644 --- a/linux-user/host/s390x/safe-syscall.inc.S +++ b/linux-user/host/s390x/safe-syscall.inc.S @@ -20,9 +20,6 @@ * first argument an 'int *' to the signal_pending flag, the * second one the system call number (as a 'long'), and all further * arguments being syscall arguments (also 'long'). - * We return a long which is the syscall's return value, which - * may be negative-errno on failure. Conversion to the - * -1-and-errno-set convention is done by the calling wrapper. */ safe_syscall_base: .cfi_startproc @@ -44,9 +41,9 @@ safe_syscall_base: stg %r1,0(%r15) /* store back chain */ stg %r0,8(%r15) /* store eos */ - /* The syscall calling convention isn't the same as the - * C one: - * we enter with r2 == *signal_pending + /* + * The syscall calling convention isn't the same as the C one: + * we enter with r2 == &signal_pending * r3 == syscall number * r4, r5, r6, (stack) == syscall arguments * and return the result in r2 @@ -77,14 +74,25 @@ safe_syscall_start: svc 0 safe_syscall_end: -1: lg %r15,0(%r15) /* load back chain */ + /* code path for having successfully executed the syscall */ + lg %r15,0(%r15) /* load back chain */ .cfi_remember_state .cfi_adjust_cfa_offset -160 lmg %r6,%r15,48(%r15) /* load saved registers */ - br %r14 + + lghi %r0, -4095 /* check for syscall error */ + clgr %r2, %r0 + blr %r14 /* return on success */ + lcr %r2, %r2 /* create positive errno */ + jg safe_syscall_set_errno_tail .cfi_restore_state -2: lghi %r2, -TARGET_ERESTARTSYS - j 1b - .cfi_endproc + /* code path when we didn't execute the syscall */ +2: lg %r15,0(%r15) /* load back chain */ + .cfi_adjust_cfa_offset -160 + lmg %r6,%r15,48(%r15) /* load saved registers */ + lghi %r2, TARGET_ERESTARTSYS + jg safe_syscall_set_errno_tail + + .cfi_endproc .size safe_syscall_base, .-safe_syscall_base |