Hi Dave, On 5/12/20 6:36 PM, Dave Martin wrote: > The prctl.2 source is unnecessarily hard to navigate, not least > because prctl option flags are traditionally named PR_* and so look > just like prctl names. > > For each actual prctl, add a comment of the form > > .\" prctl PR_FOO > > to make it move obvious where each top-level prctl starts. > > Of course, we could add some clever macros, but let's not confuse > dumb parsers. A patch like this, which makes sweeping changes across the page, should be best placed at the end of a series, I think. The reason is that if I fail to apply this patch (and I am a little dubious about it), then probably the rest of the patches in the series won't apply. (Furthermore, it also forced me to apply patch 02 already, which I wanted to reflect on a little.) That said, I'll apply it, so that the remaining patches apply cleanly. I'll consider later whether to keep this change. For example, I wonder if a visually distinctive source line that is always the same would be better than these comments that repeat the PR_* names. For example, something like .\" ========================== I'll circle back to this later. Thanks, Michael > Signed-off-by: Dave Martin <Dave.Martin@xxxxxxx> > --- > man2/prctl.2 | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 48 insertions(+) > > diff --git a/man2/prctl.2 b/man2/prctl.2 > index 9736434..e5b2b4b 100644 > --- a/man2/prctl.2 > +++ b/man2/prctl.2 > @@ -77,6 +77,7 @@ is called with a first argument describing what to do > arguments with a significance depending on the first one. > The first argument can be: > .\" > +.\" prctl PR_CAP_AMBIENT > .TP > .BR PR_CAP_AMBIENT " (since Linux 4.3)" > .\" commit 58319057b7847667f0c9585b9de0e8932b0fdb08 > @@ -130,6 +131,7 @@ library in the form of > .BR cap_set_ambient (3), > and > .BR cap_reset_ambient (3). > +.\" prctl PR_CAPBSET_READ > .TP > .BR PR_CAPBSET_READ " (since Linux 2.6.25)" > Return (as the function result) 1 if the capability specified in > @@ -152,6 +154,7 @@ A higher-level interface layered on top of this operation is provided in the > .BR libcap (3) > library in the form of > .BR cap_get_bound (3). > +.\" prctl PR_CAPBSET_DROP > .TP > .BR PR_CAPBSET_DROP " (since Linux 2.6.25)" > If the calling thread has the > @@ -178,6 +181,7 @@ A higher-level interface layered on top of this operation is provided in the > .BR libcap (3) > library in the form of > .BR cap_drop_bound (3). > +.\" prctl PR_SET_CHILD_SUBREAPER > .TP > .BR PR_SET_CHILD_SUBREAPER " (since Linux 3.4)" > .\" commit ebec18a6d3aa1e7d84aab16225e87fd25170ec2b > @@ -224,11 +228,13 @@ Some > frameworks (e.g., > .BR systemd (1)) > employ a subreaper process for similar reasons. > +.\" prctl PR_GET_CHILD_SUBREAPER > .TP > .BR PR_GET_CHILD_SUBREAPER " (since Linux 3.4)" > Return the "child subreaper" setting of the caller, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_DUMPABLE > .TP > .BR PR_SET_DUMPABLE " (since Linux 2.3.20)" > Set the state of the "dumpable" attribute, > @@ -297,6 +303,7 @@ the ownership of files in the process's > .IR /proc/[pid] > directory is affected as described in > .BR proc (5). > +.\" prctl PR_GET_DUMPABLE > .TP > .BR PR_GET_DUMPABLE " (since Linux 2.3.20)" > Return (as the function result) the current state of the calling > @@ -304,6 +311,7 @@ process's dumpable attribute. > .\" Since Linux 2.6.13, the dumpable flag can have the value 2, > .\" but in 2.6.13 PR_GET_DUMPABLE simply returns 1 if the dumpable > .\" flags has a nonzero value. This was fixed in 2.6.14. > +.\" prctl PR_SET_ENDIAN > .TP > .BR PR_SET_ENDIAN " (since Linux 2.6.18, PowerPC only)" > Set the endian-ness of the calling process to the value given > @@ -314,11 +322,13 @@ in \fIarg2\fP, which should be one of the following: > or > .B PR_ENDIAN_PPC_LITTLE > (PowerPC pseudo little endian). > +.\" prctl PR_GET_ENDIAN > .TP > .BR PR_GET_ENDIAN " (since Linux 2.6.18, PowerPC only)" > Return the endian-ness of the calling process, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_FP_MODE > .TP > .BR PR_SET_FP_MODE " (since Linux 4.0, only on MIPS)" > .\" commit 9791554b45a2acc28247f66a5fd5bbc212a6b8c8 > @@ -425,6 +435,7 @@ The arguments > and > .IR arg5 > are ignored. > +.\" prctl PR_GET_FP_MODE > .TP > .BR PR_GET_FP_MODE " (since Linux 4.0, only on MIPS)" > Return (as the function result) > @@ -442,6 +453,7 @@ The arguments > and > .IR arg5 > are ignored. > +.\" prctl PR_SET_FPEMU > .TP > .BR PR_SET_FPEMU " (since Linux 2.4.18, 2.5.9, only on ia64)" > Set floating-point emulation control bits to \fIarg2\fP. > @@ -452,11 +464,13 @@ to silently emulate floating-point operation accesses, or > to not emulate floating-point operations and send > .B SIGFPE > instead. > +.\" prctl PR_GET_FPEMU > .TP > .BR PR_GET_FPEMU " (since Linux 2.4.18, 2.5.9, only on ia64)" > Return floating-point emulation control bits, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_FPEXC > .TP > .BR PR_SET_FPEXC " (since Linux 2.4.21, 2.5.32, only on PowerPC)" > Set floating-point exception mode to \fIarg2\fP. > @@ -470,11 +484,13 @@ Pass \fBPR_FP_EXC_SW_ENABLE\fP to use FPEXC for FP exception enables, > \fBPR_FP_EXC_NONRECOV\fP for async nonrecoverable exception mode, > \fBPR_FP_EXC_ASYNC\fP for async recoverable exception mode, > \fBPR_FP_EXC_PRECISE\fP for precise exception mode. > +.\" prctl PR_GET_FPEXC > .TP > .BR PR_GET_FPEXC " (since Linux 2.4.21, 2.5.32, only on PowerPC)" > Return floating-point exception mode, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_KEEPCAPS > .TP > .BR PR_SET_KEEPCAPS " (since Linux 2.2.18)" > Set the state of the calling thread's "keep capabilities" flag. > @@ -485,6 +501,7 @@ must be either 0 (clear the flag) > or 1 (set the flag). > The "keep capabilities" value will be reset to 0 on subsequent calls to > .BR execve (2). > +.\" prctl PR_GET_KEEPCAPS > .TP > .BR PR_GET_KEEPCAPS " (since Linux 2.2.18)" > Return (as the function result) the current state of the calling thread's > @@ -492,6 +509,7 @@ Return (as the function result) the current state of the calling thread's > See > .BR capabilities (7) > for a description of this flag. > +.\" prctl PR_MCE_KILL > .TP > .BR PR_MCE_KILL " (since Linux 2.6.32)" > Set the machine check memory corruption kill policy for the calling thread. > @@ -532,6 +550,7 @@ The policy is inherited by children. > The remaining unused > .BR prctl () > arguments must be zero for future compatibility. > +.\" prctl PR_MCE_KILL_GET > .TP > .BR PR_MCE_KILL_GET " (since Linux 2.6.32)" > Return (as the function result) > @@ -539,6 +558,7 @@ the current per-process machine check kill policy. > All unused > .BR prctl () > arguments must be zero. > +.\" prctl PR_SET_MM > .TP > .BR PR_SET_MM " (since Linux 3.3)" > .\" commit 028ee4be34a09a6d48bdf30ab991ae933a7bc036 > @@ -716,6 +736,7 @@ This feature is available only if the kernel is built with the > .BR CONFIG_CHECKPOINT_RESTORE > option enabled. > .RE > +.\" prctl PR_MPX_ENABLE_MANAGEMENT > .TP > .BR PR_MPX_ENABLE_MANAGEMENT ", " PR_MPX_DISABLE_MANAGEMENT " (since Linux 3.19) " > .\" commit fe3d197f84319d3bce379a9c0dc17b1f48ad358c > @@ -791,6 +812,7 @@ had been called. > .IP > For further information on Intel MPX, see the kernel source file > .IR Documentation/x86/intel_mpx.txt . > +.\" prctl PR_SET_NAME > .TP > .BR PR_SET_NAME " (since Linux 2.6.9)" > Set the name of the calling thread, > @@ -819,6 +841,7 @@ in the buffer pointed to by > .IR "(char\ *) arg2" . > The buffer should allow space for up to 16 bytes; > the returned string will be null-terminated. > +.\" prctl PR_SET_NO_NEW_PRIVS > .TP > .BR PR_SET_NO_NEW_PRIVS " (since Linux 3.5)" > Set the calling thread's > @@ -862,6 +885,7 @@ For more information, see the kernel source file > before Linux 4.13). > See also > .BR seccomp (2). > +.\" prctl PR_GET_NO_NEW_PRIVS > .TP > .BR PR_GET_NO_NEW_PRIVS " (since Linux 3.5)" > Return (as the function result) the value of the > @@ -873,6 +897,7 @@ behavior. > A value of 1 indicates > .BR execve (2) > will operate in the privilege-restricting mode described above. > +.\" prctl PR_SET_PDEATHSIG > .TP > .BR PR_SET_PDEATHSIG " (since Linux 2.1.57)" > Set the parent-death signal > @@ -922,11 +947,13 @@ or a binary that has associated capabilities (see > .BR capabilities (7)); > otherwise, this value is preserved across > .BR execve (2). > +.\" prctl PR_GET_PDEATHSIG > .TP > .BR PR_GET_PDEATHSIG " (since Linux 2.3.15)" > Return the current value of the parent process death signal, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_PTRACER > .TP > .BR PR_SET_PTRACER " (since Linux 3.4)" > .\" commit 2d514487faf188938a4ee4fb3464eeecfbdcf8eb > @@ -959,6 +986,7 @@ For further information, see the kernel source file > (or > .IR Documentation/security/Yama.txt > before Linux 4.13). > +.\" prctl PR_SET_SECCOMP > .TP > .BR PR_SET_SECCOMP " (since Linux 2.6.23)" > .\" See http://thread.gmane.org/gmane.linux.kernel/542632 > @@ -1035,6 +1063,7 @@ For further information, see the kernel source file > (or > .IR Documentation/prctl/seccomp_filter.txt > before Linux 4.13). > +.\" prctl PR_GET_SECCOMP > .TP > .BR PR_GET_SECCOMP " (since Linux 2.6.23)" > Return (as the function result) > @@ -1061,18 +1090,21 @@ field of the > file provides a method of obtaining the same information, > without the risk that the process is killed; see > .BR proc (5). > +.\" prctl PR_SET_SECUREBITS > .TP > .BR PR_SET_SECUREBITS " (since Linux 2.6.26)" > Set the "securebits" flags of the calling thread to the value supplied in > .IR arg2 . > See > .BR capabilities (7). > +.\" prctl PR_GET_SECUREBITS > .TP > .BR PR_GET_SECUREBITS " (since Linux 2.6.26)" > Return (as the function result) > the "securebits" flags of the calling thread. > See > .BR capabilities (7). > +.\" prctl PR_GET_SPECULATION_CTRL > .TP > .BR PR_GET_SPECULATION_CTRL " (since Linux 4.17)" > Return (as the function result) > @@ -1119,6 +1151,7 @@ and > .I arg5 > arguments must be specified as 0; otherwise the call fails with the error > .BR EINVAL . > +.\" prctl PR_SET_SPECULATION_CTRL > .TP > .BR PR_SET_SPECULATION_CTRL " (since Linux 4.17)" > .\" commit b617cfc858161140d69cc0b5cc211996b557a1c7 > @@ -1174,6 +1207,7 @@ call failing with the error > .BR ENXIO . > For further details, see the kernel source file > .IR Documentation/admin-guide/kernel-parameters.txt . > +.\" prctl PR_SET_THP_DISABLE > .TP > .BR PR_SET_THP_DISABLE " (since Linux 3.15)" > .\" commit a0715cc22601e8830ace98366c0c2bd8da52af52 > @@ -1191,6 +1225,7 @@ The setting of the "THP disable" flag is inherited by a child created via > and is preserved across > .BR execve (2). > .\" > +.\" prctl PR_TASK_PERF_EVENTS_DISABLE > .TP > .BR PR_TASK_PERF_EVENTS_DISABLE " (since Linux 2.6.31)" > Disable all performance counters attached to the calling process, > @@ -1207,6 +1242,7 @@ Originally called > renamed (retaining the same numerical value) > in Linux 2.6.32. > .\" > +.\" prctl PR_TASK_PERF_EVENTS_ENABLE > .TP > .BR PR_TASK_PERF_EVENTS_ENABLE " (since Linux 2.6.31)" > The converse of > @@ -1220,11 +1256,13 @@ renamed > .\" commit cdd6c482c9ff9c55475ee7392ec8f672eddb7be6 > in Linux 2.6.32. > .\" > +.\" prctl PR_GET_THP_DISABLE > .TP > .BR PR_GET_THP_DISABLE " (since Linux 3.15)" > Return (as the function result) the current setting of the "THP disable" > flag for the calling thread: > either 1, if the flag is set, or 0, if it is not. > +.\" prctl PR_GET_TID_ADDRESS > .TP > .BR PR_GET_TID_ADDRESS " (since Linux 3.5)" > .\" commit 300f786b2683f8bb1ec0afb6e1851183a479c86d > @@ -1246,6 +1284,7 @@ system call does not have a compat implementation for > the AMD64 x32 and MIPS n32 ABIs, > and the kernel writes out a pointer using the kernel's pointer size, > this operation expects a user-space buffer of 8 (not 4) bytes on these ABIs. > +.\" prctl PR_SET_TIMERSLACK > .TP > .BR PR_SET_TIMERSLACK " (since Linux 2.6.28)" > .\" See https://lwn.net/Articles/369549/ > @@ -1316,10 +1355,12 @@ can be examined and changed via the file > .IR /proc/[pid]/timerslack_ns . > See > .BR proc (5). > +.\" prctl PR_GET_TIMERSLACK > .TP > .BR PR_GET_TIMERSLACK " (since Linux 2.6.28)" > Return (as the function result) > the "current" timer slack value of the calling thread. > +.\" prctl PR_SET_TIMING > .TP > .BR PR_SET_TIMING " (since Linux 2.6.0)" > .\" Precisely: Linux 2.6.0-test4 > @@ -1338,11 +1379,13 @@ is not currently implemented > .\" PR_TIMING_TIMESTAMP doesn't do anything in 2.6.26-rc8, > .\" and looking at the patch history, it appears > .\" that it never did anything. > +.\" prctl PR_GET_TIMING > .TP > .BR PR_GET_TIMING " (since Linux 2.6.0)" > .\" Precisely: Linux 2.6.0-test4 > Return (as the function result) which process timing method is currently > in use. > +.\" prctl PR_SET_TSC > .TP > .BR PR_SET_TSC " (since Linux 2.6.26, x86 only)" > Set the state of the flag determining whether the timestamp counter > @@ -1356,12 +1399,14 @@ to allow it to be read, or > to generate a > .B SIGSEGV > when the process tries to read the timestamp counter. > +.\" prctl PR_GET_TSC > .TP > .BR PR_GET_TSC " (since Linux 2.6.26, x86 only)" > Return the state of the flag determining whether the timestamp counter > can be read, > in the location pointed to by > .IR "(int\ *) arg2" . > +.\" prctl PR_SET_UNALIGN > .TP > .B PR_SET_UNALIGN > (Only on: ia64, since Linux 2.3.48; parisc, since Linux 2.6.15; > @@ -1385,6 +1430,7 @@ flag in > operation of the > .BR setsysinfo () > system call on Tru64). > +.\" prctl PR_GET_UNALIGN > .TP > .B PR_GET_UNALIGN > (See > @@ -1392,6 +1438,7 @@ system call on Tru64). > for information on versions and architectures.) > Return unaligned access control bits, in the location pointed to by > .IR "(unsigned int\ *) arg2" . > +.\" prctl PR_SET_IO_FLUSHER > .TP > .BR PR_SET_IO_FLUSHER " (since Linux 5.6)" > If a user process is involved in the block layer or filesystem I/O path, > @@ -1420,6 +1467,7 @@ and is preserved across > Examples of IO_FLUSHER applications are FUSE daemons, SCSI device > emulation daemons, and daemons that perform error handling like multipath > path recovery applications. > +.\" prctl PR_GET_IO_FLUSHER > .TP > .B PR_GET_IO_FLUSHER (Since Linux 5.6) > Return (as the function result) the IO_FLUSHER state of the caller. > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
