varun-r-mallya/sysprof
1
0
Fork 0
mirror of https://github.com/varun-r-mallya/sysprof.git synced 2025-12-31 20:36:25 +00:00
Code Issues Packages Projects Releases Wiki Activity

mapped-ring-buffer: Round to the shared memory boundary on hppa

Browse Source 
In map_head_and_body_twice(), the second mmap call fails:

mmap2(NULL, 135168, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = 0xf64a2000
mmap2(0xf64b3000, 65536, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, 3, 0x1000) = -1 EINVAL (Invalid argument)

Due to cache issues, all shared mapping of a page must be equivalently
mapped.  This requires page mappings to be at the same virtual address
modulo 4 MB.  Due to a kernel limitation, all mappings to a file must
be equivalent.

The test can be fixed by rounding the buffer_size used in the mapped
ring buffer to 4 MB on hppa.  This makes the two mmap mappings equivalent.

Bug-Debian: https://bugs.debian.org/1021853
This commit is contained in:
John David Anglin
2022-10-16 01:40:46 +00:00
committed by Jeremy Bícha
parent 8ee813c9a9
commit b129c7dea2
1 changed files with 9 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
src/libsysprof-capture/mapped-ring-buffer.c
View File

@ -71,6 +71,7 @@
#define DEFAULT_N_PAGES 63
#define BUFFER_MAX_SIZE ((UINT32_MAX/2)-_sysprof_getpagesize())
#define SHM_COLOUR 0x00400000
enum {
MODE_READER = 1,
@ -209,9 +210,16 @@ mapped_ring_buffer_new_reader (size_t buffer_size)
page_size = _sysprof_getpagesize ();
/* Add 1 page for coordination header */
if (buffer_size == 0)
buffer_size = page_size * DEFAULT_N_PAGES;
#ifdef __hppa__
/* Round buffer_size up to the shared memory colour boundary */
buffer_size += SHM_COLOUR - 1;
buffer_size &= ~(SHM_COLOUR - 1);
#endif
/* Add 1 page for coordination header */
buffer_size += page_size;
/* Create our memfd (or tmpfs) for writing */